Chemical Information Sources/Synthesis and Reaction Searches
Synthetic chemists are interested in a variety of information when planning a synthesis. That may include the conditions under which the reaction is to occur, the starting materials and reagents, catalysts, reaction sites, yields, products, by-products, functional group transformations, bonding changes, and mechanisms of the reactions. A REACTION MECHANISM is "a detailed description of a particular reactant to product path, together with information pertaining to intermediates, transition states, stereochemistry, the rate-limiting step, electronic excitation and transfer, and the presence of any loose or intimate electron ion pairs." (Ash, 1985) A combination of some or all of these concepts may provide a path to the needed information, depending on the secondary source that is used. Once a compound has been synthesized, a variety of analytical and physical property techniques may be used to verify that the correct substance has been made.
One way to search for reaction information is by the name of the reaction. That may be a more general name, such as a substitution reaction, or it may be an eponym from the name of the chemist(s) who first developed the synthetic method, such as the Curtius Rearrangement Reaction. Other search systems have developed around codes for various key features in the reaction.
One can, of course, search large databases, such as Chemical Abstracts, for reaction information. But in recent years, a number of specialized reaction chemistry databases have come on the scene to assist in a search for reaction information. In addition, there are specialized printed sources that codify the many discoveries in the reaction chemistry area. Some of the most important sources are discussed in this chapter.
Beilstein, Gmelin, and Reaxys 
The Beilstein Handbook of Organic Chemistry and the Gmelin Handbook of Inorganic and Organometallic Chemistry are two comprehensive sources that include preparation and formation information. Of course, for the printed older volumes it is necessary to cope with the text in German, but here is a list of selected German words for reaction chemistry that should assist you.
A search of the CrossFire Beilstein Database for "Isatin" shows that the record for the compound had at the time of the search 2003 entries for Reaction and 6 entries for Isolation from a Natural Product. It also included 15 Derivatives. One of the references is:
|Reaction ID: 123539|
|Reactant BRN 131835: 3-hydroxy-1,3-dihydro-indol-2-one|
|Product BRN 383659: indole-2,3-dione|
|Reaction Classification: Preparation|
|Reagent: ammonium nitrate, acetic acid|
|Ref 1 1046338; Journal; Klein; JACSAT; J.Amer.Chem.Soc.; 63; 1941; 1474.|
Note that the Beilstein Registry Number (BRN) for isatin, 383659, is not the same as the Chemical Abstracts Service Registry Number for the compound, 91-56-5. Not all compounds in Beilstein have CAS RNs, and it is not recommended to search the database that way. In fact, the preferred way to search for a compound in Beilstein is by structure.
Thus, we see that it is possible to find reaction information using the compound name or structure if the record for the compound is among the many millions of compounds currently in the database on Reaxys (successor to the CrossFire system), that includes both Beilstein and Gmelin. An impressive feature of this and other structure-enabled search systems for reactions is the capability to input the structure of a starting material and/or the structure of a desired product and conduct a reaction query. When at least two depictions of chemical substances are drawn on the screen and one is selected, the reaction editing component of the CrossFire system appeared, giving the option to define the selected substance as either a Reactant or a Product. It was even possible to graph one or more atoms from the Reactant molecule onto a position in the Product in order to insure that the reaction(s) found in the search would allow the desired modifications to occur only at specific points on the molecule.
You could also just draw the target structure and assign the role - reactant or product - using the radio buttons in the CrossFireCommander 7 series.
At the time of the graphical search, 60 reactions were found in which isatin was a product, and the third of those is shown below. Please note that Beilstein and Gmelin collate reportings of the same reacton with different conditions from different publications in one display for the reaction.
The Gmelin database joined Beilstein in the CrossFire family of searchable databases. From v. 6.0 of the CrossFire software and the Gmelin database at the beginning of 2002, it became possible to do graphical reaction searching in Gmelin. Now both databases are integrated into the Reaxys system.
Houben–Weyl Methods of Organic Chemistry 
Houben-Weyl is one of the most significant and comprehensive reference works ever published in the field of organic synthesis. It contains a mass of useful and insightful synthetic methodology information for the synthetic organic chemist. The content covers preparative methods for different compound classes and treats them comprehensively and critically. Extensive tables of examples show their scope and limitations. Detailed experimental procedures are given for the most important methods. Also, there is an introductory section for each compound class which covers an overview of structure, reactivity, stability, spectroscopic characteristics, nomenclature, natural occurrence and applications. Although 75% of the content was published in German, the publisher, Georg Thieme Verlag KG, has produced numerous tools to help English native speakers navigate their way around the volumes. These include translated table of contents which are text-searchable online, formulae-containing indexes, user guides and posters.
The series Methoden der Organischen Chemie (Houben–Weyl Methods of Organic Chemistry) was established in 1909 by the German chemist Theodor Weyl and continued in 1913 by Heinrich J. Houben. The comprehensive description of preparative methods in a consistent style and their critical evaluation by leading experts constitute the philosophy on which Houben–Weyl was founded. The 4 volumes of the second edition were published between 1921 and 1924. The third edition, consisting of 4 volumes, was published between 1924 and 1941. The fourth edition began in 1952 and ended in 1986 with a total of 67 volumes and 3 index volumes. The series was updated with 89 additional and supplementary volumes, which placed emphasis on the treatment of important classes of compounds and significant preparative methods. From 1990 onwards, Houben–Weyl was published in English, thus making it accessible to chemists worldwide. The last volume of Houben–Weyl was published in 2003. The total series consisted of 140 volumes and 157,262 pages.
Houben-Weyl Structure 
Houben-Weyl is organized by class of compound or functional group to be synthesized. Thus, it is structured according to the type of product formed, with only the principal function considered. This is determined by the level of oxidation, substitution or saturation of the carbon atom(s). In general, higher oxidation levels have priority over lower ones and heterofunctional atoms or groups are classified according to a priority list that puts CX3 at the top and P at the bottom. In Houben-Weyl, transformations of the principal functional group are illustrated by typical examples. Patents are included in the scope of coverage, and the important preparative methods for all classes of compounds are presented.
Science of Synthesis 
Scope and Background 
The Houben-Weyl legacy archive has been available online since 2001 and is included as the backfile in the electronic version of Science of Synthesis.
Science of Synthesis is an entirely new edition of Houben-Weyl designed to cater to the broader information needs of the synthetic organic chemist today. It is considered to be the best secondary source of information other than the original journal articles for methods of synthesis of the functional groups covered. It consists of 48 volumes to be published in print and online between 2000 and 2009. As of mid-2007, 28 of the volumes had been published, with the majority available online. Over 650 renowned organic chemists worldwide have been involved with or are currently working on contributions to the project.
The purpose of Science of Synthesis is to critically evaluate all existing methods in organic and organometallic chemistry. The most important molecular transformations for a product class are selected and their scope and limitations summarized. In addition the transformations are further illustrated using proven general or typical methods. Contributions contain background information, a comparison of methods, mechanistic rationale, stereochemistry, experimental procedures, information on scope, limitations and problems, functional group compatibility, and safety and environmental aspects.
The organization of Science of Synthesis is based on the structural unit or functional group (for example, a heteroaromatic ring or an enone) that is to be constructed. That is to say, the classification is based on the product (how do I make something?) as opposed to the reaction (what is the Horner–Emmons reaction?), the reagent (what can I do with organocopper reagents?), or the starting material (what reactions do 1,2-diols undergo?). Thus, a synthetic method, such as catalytic hydrogenation, that can be employed for a variety of product types, will be found throughout the work, depending on the structure of the compound produced. Likewise, the various reactions of a given compound class, such as alcohols, are located throughout the work on the basis of the product.
Online Product 
The online product has been available since 2001 and supports combined keyword, text, and reaction searches. Version 3.2 (2007) contains 26 volumes and over 140,000 reactions. Crossovers to databases and electronic journals are fully supported, thus allowing chemists to gather further information about their target compounds. The electronic product has browsing features and an interactive table of contents to enable easy navigation within the product. The product is better described as an e-reference book as opposed to a database because of the wealth of knowledge around each of the reactions and the context within which they are presented.
Some of the functionality/features available include exact and substructure searching, reaction searching, refinement of structure searches (catalyst, solvent, and reactant/product specification possible), full text search, fully searchable indexes (catalyst, solvent, author, books/journal, yield, temp.), bibliographic search, table of contents browsing, single-step reaction searches, cross-linked chapters, digital object identifiers, print functionality, search history, CAS registry numbers, name reactions, and fully linked backfiles.
Organic Syntheses 
Organic Syntheses began publication in 1921 and is published annually. The procedures are cumulated into collective volumes (with revisions if necessary). Ten of the collective volumes covering annual volumes have been published to date. The articles are sufficiently detailed so that the reactions described can usually be carried out without consulting the original primary literature. In later years, the emphasis has been on model compounds and procedures that illustrate important types of reactions. The 1991 Organic Syntheses Reaction Guide covers experimental procedures in Collective Volumes 1-7 and annual volumes 65-68. Eleven broad classes of reactions are used to index the reactions. Elsevier MDL also makes available to its customers the ORGSYN database that covers the entire Organic Syntheses collection, and from 2001, a version of the Organic Syntheses database is available on the Web for free searching. It requires the installation of the free ChemDraw Net plugin from CambridgeSoft, but once that is in place, even structure searches can be performed. Additional ways of searching the database include CAS RN, molecular formula, and chemical name, plus author and keyword searching. Below is the result of a structure search on Organic Syntheses for Isatin.
Clicking on html or pdf will bring you to the detailed synthesis procedure.
Treatises, Collected Works, and Other Important Works. 
As is typical of the long publication span of most treatises, Inorganic Reactions and Methods began publication in 1986 and was completed in 1999. Volumes cover ways of forming bonds with inorganic elements, methods of effecting various types of reactions, and methods of characterizing the compounds. The set is well indexed. Of particular note is a permuted formula index which groups all compounds containing a given number of an element in one section of the index.
The Formation of Bonds to Hydrogen, 1-2
|3-4||1989-91||The Formation of Bonds to Halogens, 1-2|
|5-6||1991-98||The Formation of Bonds to O, S, Se, Te, Po, 1-2|
|7-8||1988-95||The Formation of Bonds to N, P, As, Sb, Bi, 1-2|
|9-12||1988-91||The Formation of Bonds to C, Si, Ge, Sn, Pb, 1-4|
|13||1991||The Formation of Bonds to Group-I, -II, and -IIIB Elements|
|14||1998||The Formation of Bonds to Transition and Inner-Transition Metals; Oxidative-Addition and Reductive-Elimination Reactions; Insertion Reactions and Their Reverse|
|15||1986||Electron Transfer and Electrochemical Reactions; Photochemical and Other Energized Reactions|
|16||1993||Reactions Catalyzed by Inorganic Compounds|
|17||1990||Oligomerization and Polymerization; Formation of Intercalation Compounds|
|18||1999||Formation of Ceramics|
|Part 1. Author and Subject. Part 2. Compound.|
Volumes in the Treatise Inorganic Reactions and Methods
Another important inorganic set is Synthetic Methods of Organometallic and Inorganic Chemistry.
Literature, Laboratory Techniques, and Common Starting Materials
|2||1996||Groups 1, 2, 13, and 14|
|3||1996||Phosphorus, Arsenic, Antimony, and Bismuth|
|4||1997||Sulfur, Selenium, and Tellurium|
|5||1998||Copper, Silver, Gold, Zinc, Cadmium, and Mercury|
|6||1996||Lanthanides and Actinides|
|7||1997||Transition Metals, Part 1|
|8||1997||Transition Metals, Part 2|
|9||1999||Transition Metals, Part 3|
|10||1998||Halogen Compounds and Rare Metals|
A longstanding inorganic series that has appeared since 1939 is Inorganic Syntheses, for which a collective index of volumes 1-30 of the series covering 1939-95, has now appeared. The Encyclopedia of Inorganic Chemistry in 8 volumes (1994) covers all aspects of inorganic chemistry, including information on reactions and bonding energetics.
Pergamon Press has published a large number of multi-volume treatises on various areas of chemistry over the years:
- Comprehensive Inorganic Chemistry (1973)
- Comprehensive Organic Chemistry (1979)
- Comprehensive Organic Synthesis (1991)
- Comprehensive Organic Functional Group Transformations (1995)
- Comprehensive Heterocyclic Chemistry (1984)
- Comprehensive Heterocyclic Chemistry II (1996)
- Comprehensive Organometallic Chemistry (1982)
- Comprehensive Organometallic Chemistry II (1995)
- Comprehensive Coordination Chemistry (1987)
- Comprehensive Polymer Science (1988)
- Comprehensive Medicinal Chemistry (1988)
- Comprehensive Medicinal Chemistry II (2007)
- Comprehensive Supramolecular Chemistry (1996)
- Comprehensive Natural Products Chemistry (1999)
- Comprehensive Composite Materials (2000).
A major thrust of the Pergamon treatises is syntheses and reactions. Each of the sets has a distinguished editorial board and is thoroughly referenced to the original primary literature. A feature of some of the treatises is an index of review articles and specialist textbooks relevant to the topic. A few of the earlier Pergamon treatises, Comprehensive Heterocyclic Chemistry and Comprehensive Medicinal Chemistry, were made into searchable databases by Elsevier MDL Information Systems Inc. (formerly, Molecular Design Ltd.). Elsevier MDL also produces the Available Chemicals Directory (ACD), a database that combines the catalogs of dozens of chemical suppliers. Suppliers of reagents can also be identified by using the link from the Registry File summary in SciFinder Scholar to the CHEMCATS database. Hundreds of suppliers are found in CHEMCATS.
It is often useful to find a description of a reagent to determine whether it has been used in the preparation of a given compound or a compound that is similar to the one which is to be made. A recent set is the 8-volume Encyclopedia of Reagents for Organic Synthesis (1995). The preface to the work notes the "vital need to know which reagent will perform a specific transformation." Over 3,000 reagents are arranged alphabetically by IUPAC name. These include reagents, auxiliaries, and catalysts for C-C bond formation; oxidizing and reducing agents; acidic and basic reagents; activating agents and protecting groups; chiral reagents for asymmetric synthesis; reagents for high-throughput solid-phase and solution-phase organic synthesis; reagents for glycoside, nucleotide, and peptide synthesis; and reagents for direct functionalization of C-H bonds. The set is indexed by formula, structural class, function, and subject indexes. Beginning in 2001, a new version of e-EROS is available only on the Web as a subscription item from Wiley. An offshoot of EROS is the four-volume Handbook of Reagents for Organic Synthesis (2000). Intended as a lower-cost reference work that would be available in or near laboratories, the Handbook includes information from the original 8-volume work. It covers in separate volumes: "Reagents, Auxiliaries, and Catalysts for C-C Bond Formation," "Oxidizing and Reducing Agents," "Acidic and Basic Reagents," and "Activating Agents and Protecting Groups."
Prior to the appearance of EROS, the venerable Fieser and Fieser's Reagents for Organic Synthesis (1967-) had been the standard source for reagents. It is especially useful for planning a synthesis and for answering questions that may arise in the course of a synthesis. One can find information on methods of preparation or purification, uses, suppliers, and reaction diagrams. Indexes for reactions, methods, authors, and subjects are provided.
Larock's Comprehensive Organic Transformations: A Guide to Functional Group Preparations first appeared in 1989, with coverage of the literature through 1987. Almost 15,000 reactions and over 23,000 references were included for reactions that yield over 50%. A CD-ROM version of the first edition of the work appeared in 1997, and the revised print edition, published in 1999, extended the literature coverage for selected journals through 1995.
More thorough coverage of "The Chemistry of Functional Groups" can be found in the volumes that bear that series name. Entire volumes are dedicated to topics such as The Chemistry of Alkenes (1964), The Chemistry of Enols (1990), etc. A useful means of finding an appropriate volume in the series is Saul Patai's Guide to the Chemistry of Functional Groups Series.
Bretherick's Reactive Chemical Hazards is the place to look for information on all types of dangerous reactions. Included is every chemical for which documented information on reactive hazards has been found over the years. With the fifth edition, Bretherick's began to appear in CD-ROM as well as print formats.
Reaction Databases and Specialized Abstracting Services. 
As noted above, it is possible to find reaction information in more general A&I services, such as Chemical Abstracts. However, there are a number of special services that are devoted to reaction or synthetic chemistry. As such, they pay more attention to the aspects of the literature that are important to the reaction chemist. Among the specialized A&I services are:
- Index Chemicus
- Current Chemical Reactions
- Reaction Citation Index
- Journal of Synthetic Methods
- Theilheimer's Synthetic Methods of Organic Chemistry
- Methods in Organic Synthesis
- Natural Product Updates
- Annual Reports in Organic Synthesis
- InfoChem's SPRESIweb
The Index Chemicus database, now available on the Web of Science, reports on over 200,000 new compounds each year. Those are found in over 100 of the leading natural products, agrochemical, organic, and medicinal chemistry journals. Index Chemicus, which began publication in 1960, is unique in that it includes un-isolated synthetic intermediates in the database. Biological activity is one of the properties indexed. In addition to the printed Index Chemicus, the product is now available on CD-ROM for Windows and as a Web database. Coverage of the database begins with 1992.
The companion product Current Chemical Reactions split off from Index Chemicus in 1979. CCR has examples of reaction types. The CCR database, which exists in Elsevier MDL formats and Daylight Chemical Information Systems' reaction system, covers over 400,000 reactions since 1986. It allows you to find synthetic routes by searching the substructure of the product. Current Chemical Reactions provides backfiles to 1986, plus INPI (the French national patent office) archives from 1840 to 1985.
A hybrid in the reaction chemistry product line of Thomson Reuters is the Reaction Citation Index. The database provides search avenues via reaction data from Current Chemical Reactions, but has the unique feature of cited reference searching with references taken from the Science Citation Index bibliographic database.
Derwent's Journal of Synthetic Methods began publication in 1975 as a successor to a loose-leaf service that supplemented the annual Theilheimer's Synthetic Methods of Organic Chemistry. It had long been available as a database on Questel (ORBIT) and is now on the STN International online system as file DJSMDS/DJSMONLINE. There is also an accelrys version of JSM. The database gives a structure-searchable approach to novel synthetic methods from the worldwide patent literature (about 14 percent of the total citations) and scientific journal literature. Only new methods or the most synthetically useful modifications of known methods are abstracted. Consequently, only about 3,000 reactions each year enter the database. All references are cross-referenced to relevant prior art and other similar reactions. On STN, the page images of the printed Derwent Journal of Synthetic Methods are included for all records. The annual Theilheimer volumes also continue to be published. Elsevier has over 46,000 reactions from volumes 1-34 (1946-81) of Theilheimer as a database.
Also on STN is the SYNTHLINE Drug Synthesis Database that contains the schemes for synthesis of drugs currently on the market or in development worldwide from 1984 to the present.
accelrys also markets some specialized synthesis databases. Included is the Current Synthetic Methodology (CSM) database, which covers innovative and significant reactions from 1992 onward. The reaction data in CSM is a subset of the much larger ChemInform RX database, also available from accelrys. accelrys makes availables their synthesis databases through the DiscoveryGate software. Among their specialized reaction databases are:
- Available Chemicals Directory
- Screening Compounds Directory
- Cheminform Reaction Library
- Comprehensive Medicinal Chemistry
- Reference Library of Synthetic Methodology
- Derwent Journal of Synthetic Methods
- National Cancer Institute Database
- Solid-Phase Organic Reactions
- ORGSYN (Organic Syntheses) Database
With the fall of the Soviet Union a huge database of single-step reactions, whose source articles contain synthesis data, became available in several formats. Produced by the USSR Academy of Sciences All-Union Institute of Scientific and Technical Information (VINITI) and the Zentrale Informationsverarbeitung Chemie (ZIC) in Berlin, InfoChem originally contained over 2.2 million compounds, with over 1.8 million reactions from 1975-88. Now enhanced, the SPRESIweb structural and reaction database is provided via the Internet by InfoChem GmbH. The entire InfoChem database with 2.5 million reactions is also available in CD-ROM format from Springer-Verlag. A subset containing 370,000 reaction types searchable by structure was formerly available as the CHEMREACT file on STN. In 2001, CAS integrated the data with its CASREACT database. Smaller structure-searchable subsets have been produced by Springer-Verlag for PC platforms. For the Windows environment, these are called ChemReactXX, with the number of reactions indicated by the XX in the title. For example, ChemReact41 is a Windows CD-ROM set with 41,000 high-yield reaction types. (Versions with 10,000 and 32,000 reactions were also sold). Other variants of the database included a version that worked with Chemical Design Ltd's ChemRXS (absorbed by Accelrys). As noted above, accelrys now has a version of SPRESI.
ChemInformRX is a database produced by FIZ Chemie GmbH. The database can be searched on the STN system. It includes CAS Registry Numbers for all reactants, products, reagents, solvents, and catalysts. Reactants, reagents, and products are structure searchable in a single search. Coverage is from 1991 to the present.
The CASREACT file on STN has reaction information from the organic sections of Chemical Abstracts from 1907 to the present, as well as other sources that extend the coverage for journals and patents back to 1840. Originally only journal articles were covered in CASREACT, but since January 1991, patents are also included. The patent coverage was substantially increased in 2001 by the addition of records from 1974-1984 that are derived from the ZIC/VINITI data file provided by InfoChem. Now the CAS reaction literature extends back to 1840, with more than 64.3 million reactions covered.
Both single-step and multi-step reactions are included. No reactions involving inorganic or coordination compounds or polymers are found in CASREACT. However, for the documents covered, the records contain structure diagrams for reactants and products. CAS Registry Numbers are found for reactants, products, reagents, solvents, and catalysts. The yields are given for many products, and textual information also describes the reactions. Mapping of atoms between reactants and products is possible in a structure search.
CASReact is one of the databases accessible through CAS's SciFinder product. Once a structure is drawn, you have a number of options to refine the retrieved records, including:
- limit with another structure
- limit by percent yield
- limit by the number of steps in the reaction
- limit by reaction classification (chemoselective, combinatorial, gas-phase, etc.)
The images below show the sequence of a search for isatin and the carboxylic acid functional group in a reaction.
Chemical Abstracts and CA Databases. 
When searching Chemical Abstracts or the corresponding database, you need to keep in mind the criteria for indexing a chemical substance. A compound is indexed in CA only if:
- something new is reported about a known compound
- it is a new compound that has been isolated and characterized.
Thus, even though an article might include the preparation of derivatives, if the only purpose was to facilitate isolation or analysis of a parent compound, no index entries would be made for the derivatives (unless some new data about them appeared in the article). CAS chooses the most specific term possible for indexing purposes, for example, the name of a specific compound is preferred over the class of compounds to which it belongs and the name of a more specific class is chosen over a more general class of substances. A class entry (for example, esters) is made in indexing a document only under certain circumstances:
- when only that class of compounds is discussed in the document
- when a specific compound cannot be represented by a CAS Registry Number
- when the document is a review.
The substance class heading is chosen to be as specific as possible, for example, aromatic hydrocarbons instead of the broader term hydrocarbons if the document discusses only aromatic hydrocarbons.
In the printed CA Chemical Substance Index, at the very beginning of the entries for a given compound, you will often encounter abstract numbers immediately following the compound name and CAS Registry Number. There is no accompanying text to indicate what information is contained in the document. This CAS convention implies that the preparation of the substance is the main thrust of the document. Thus, in the 1987-1991 Chemical Substance Index is found:
| 1H-Indole-2,3-dione (isatin) [91-56-5]
| 112: 7313u, 198038r
| absorption spectra of, in relation to dimethylindigo,
| 115: 258278t
The subject of the first two items is apparent from the titles:
112: 7313u An improved synthesis of isatin. Alam, M.; Younas, M.; Zafar, M. A.; Naeem (Dep. Pharm., Univ. Punjab, Lahore, India). Pak. J. Sci. Ind. Res. 1989, 32(4), 246 (Eng).
112: 198038r Convenient preparation of 3,3-dibromo-1,3-dihydroindol-2-ones and indole-2,3-diones (isatins) from indoles. Parrick, John; Yahya, Arbaeyah; Ijaz, Abdul S.; Yizun, Jin (Chem. Dep., Brunel Univ., Uxbridge/Middlesex, UK UB8 3PH). J. Chem. Soc., Perkin Trans. 1 1989, (11), 2009-15 (Eng).
Functional derivatives follow the entry for the parent compound (the Heading Parent) in the Chemical Substance Index.
CAS ROLES. 
CAS Roles are indexing terms in the CA/CAplus databases. Roles originally were provided for database entries from midway in the v. 121 indexing (from October 1994). They were later applied via a computer algorithm to all database entries beginning with 1967. There are nine super roles, each with more specific words used to describe the information that deals with the substances indexed in a document. One of the super roles is PREP (Preparation), which has more specific roles:
- BMF Bioindustrial manufacture
- BPN Biosynthetic preparation
- BYP Byproduct
- CPN Combinatorial preparation
- IMF Industrial manufacture
- PUR Purification or recovery
- SPN Synthetic preparation.
Reviews of Reaction or Synthetic Chemistry. 
Theilheimer's Synthetic Methods of Organic Chemistry begins each annual volume with a review article "Trends in Synthetic Organic Chemistry." The database Synthesis Reviews began to appear in 1995 as a supplement to the journal Synthesis. With the 1996 update, the database covers over 7500 articles and books and is supplied in EndNote Plus format. The annual survey Organic Reactions (1942-) covers well-defined reactions, such as name reactions. The latest volume has a cumulative list of all chapters in earlier volumes, and there are cumulative author and chapter/topic indexes that cover all volumes published.
A journal from the Royal Society of Chemistry is Contemporary Organic Synthesis (1994-). The Royal Society also publishes two alerting services, Natural Product Reports (1987-) for bio-organic chemistry, and Methods in Organic Synthesis (1984-). In 2001, the RSC made the two products available to subscribers on the Web, with references from the year 2000 onward. See NPU and MOS. Here is a link to other review serials that cover the areas of synthesis or reaction chemistry.
Name Reactions. 
The Fischer indole synthesis, the Claisen rearrangement, the Wolff-Kishner reduction, Beckmann rearrangement, and the Friedel-Crafts reaction--a person who is well versed in synthetic chemistry techniques may know all of these reactions. However, there are hundreds of others that bear the names of their discoverers, and sometimes a reference to them can be perplexing. To help in this regard, compilations of so-called name reactions have been published over the years. The most recent to appear are:
- Goutam's Organic Name Reactions: A Unified Approach (2006)
- Hassner and Stumer's Organic Syntheses Based on Name Reactions (2nd ed., 2002)
- Mundy, Ellerd, and Favaloro's Name Reactions and Reagents in Organic Synthesis (2nd ed., 2005).
- Laue and Plagens' Named Organic Reactions (2nd ed., 2005)
Another such work, focused on natural product synthesis, is Strategic Appplications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms (2005).
A chemist who needs to find information on the synthesis or reaction of chemical substance(s) now has a wealth of printed and online reference sources from which to choose. Chemical Abstracts Service and other database producers and vendors have made great strides in providing intuitive interfaces for chemists to locate the needed information. Very detailed reaction information is available in tools such as Science of Synthesis and CASReact. There is rich coverage of the literature stretching far back into the 19th century.