Markush

SMILES simplest linear code easy to learn fast data exchange formal supports Markush, slcrcochcmistiy, and reaction coding unambiguous not unique (except Unique SMfl FS) some problems with aromaticity perception... 

Maikush structures are mainly used in patents, for protecting compounds related to an invention. The first generic claim, submitted by Markush, was granted in 1924 by the US Patent Office [87-90]. 

Nowadays, Markush structures are utilixed mainly in patent databases, where they describe a number of different chemical compounds. Searching in patent databases is very important for companies to ascertain whether a new compound is... 

Figure 2-62. The substituted phenyl derivative is an example of a typical Markush structure. Herein, a number of compounds are described in one structure diagram by fill-ins. Phenylalanine is one of these structures when r is COOH, is H, and X is H.

Today, fragment coding is still quite important in patent databases (sec Chapter 5, Section 5.11, e.g., Dei went) where Markush structures are also stored. There, the fragments can be applied to substructure or othei types of searches where the fragments arc defined, c.g., on the basis of chemical properties. 

Markush structures rcprcHL-uts compound families - widespread in patents nianual in/ontput convertible into otlicr representations high number of compounds less compact code ambiguous difficult to extract individual compounds... 

Patent databases are therefore integrated databases because facts, text, tables, graphics, and structures are combined. In patents that include chemical aspects (mostly synthesis or processing), the chemical compounds are often represented by Markush structures (see Chapter 2, Section 2.7.1). These generic structures cover many compound families in a very compact maimer. A Markush structure has a core structure diagram with specific atoms and with variable parts (R-groups), which are defined in a text caption. The retrieval of chemical compounds from Markush structures is a complicated task that is not yet solved completely satisfactorily. 

MARPAT Chemical Abstracts Service (CAS), USA Markush structures in patents struc- ture, Mar- kush, biblio. 180000 records, 505 000 Markush struct. patent ofBces STN commercial CD-ROM, online weekly www.cas.org/ ONLINE/ DBSS/mar- patss.html... 

Fig. 3. Typical Markush structure where R is H, C 2o kylj i-20 sulfonate, or carboxylate is H or alkyl and X is H, alkyl, phenyl...

MARPAT, MARPAT Previews STN Chemical Abstracts Service international, chemistry stmcture-searchable Markush formulas in addition to other data searchable in the CA FUe, CAPlus, or CA Previews... 

Chemical Abstracts and GAS Registry. CAS is especially notable for the thoroughness and high quaUty of its products. The CAS Registry system does a superb job of identifying any chemical that is either involved in new chemistry with hard data, or, since about 1980, specifically claimed in a patent. The MARPAT database has also led CAS to identify the perhaps nonexistent but prophetic substances covered by Markush claims in patents. 

We should not minimize the effects that electronic searching of patents has had on the business of research. In 1990, CAS introduced MARPAT, which is a database of Markush (generic) structures found in patent documents [1]. This database provided a valuable tool for patent searching in a more comprehensive way than had been available previously. In 1995, CAS launched SciFinder, which provided access to the patent literature for chemists on their desktops. Using the SciFinder interface, one may search for research topics, authors, companies, or structures/reactions. From a practical viewpoint, SciFinder did more to enhance the searching capabilities of the medicinal chemist than any other tool. Even today, SciFinder continues to provide a first pass through the patent literature when chemists want to include patents in their searching. Indeed, when a search is performed, patent references are included in the answer set. Only very recently have there been additional tools to search the patent literature that have found widespread use. 

The concept of minimum AE and maximum Emw is illustrated with the generalized sequence shown in Scheme 4.7 under stoichiometric conditions with complete recovery of reaction solvents, catalysts, and post-reaction materials. Markush structures are used to show both variable R groups and necessarily invariant atoms. This analysis is useful in studying combinatorial hbraries where a constant scaffold structure is selected and then is decorated with, in principle, an unlimited number of possible R groups. 

Markovnikov rule, 20 774 Markov property, 26 1022 Markush chemical structures, indexing and searching, 18 242. See also WPI entries... 

Markush DARC system, 18 212, 230, 245 Markush structures, 18 206 Markush TOPFRAG programs, 18 226 Marl, 15 28... 

WPI database, 18 223-225, 243, 246 WPI Markush database, 13 246. See also Markush entries... 

WPIM Markush database, 13 242 Wrapping papers, 13T29 Wrinking... 

Barnard, J.M., Downs, G.M., ScHOLLEY-PFAB, A.V., and Brown, R. D. Use of Markush structure analysis techniques for descriptor generation and clustering of large combinatorial libraries./. Mol. Graph. 2000, 38, 452-463. 

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