Structures Systems Merck

Note System Cellulose layer (0.1 mm, Merck Art. 5716) developing solvent p.e.-acetone (80 20) the presence or absence of structural features is indicated. 

As previously described, Eq. 6 contains two constants characteristic of the system and the sample, feo and S, which can be determined by two chromatographic mns differing only in tc. These two values allow to calculate log fe using Eq. 4. However, because there is no empirical solution, values of log few and S have to be computed by iteration. Such procedures are included in several commercially available LC software packages, such as Drylab (Rheodyne, CA, USA), Chromsword (Merck, Darmstadt, Germany), ACD/LC simulator (Advanced Chemical Development, Toronto, Canada) or Osiris (Datalys, Grenoble, Erance). This approach was comprehensively described and successfully applied for accurate log P determination of several solutes with diverse chemical structures [9, 12, 43, 50]. 

Brown and others [12] describe the Merck, Sharp, and Dohme chemical structure information system which utilizes this approach. 

Brown, H. D., Marianne Costlow, Frank A. Cutler, Albert N. DeMott, Walter B. Gall, David P. Jacobus, and Charles J. Miller, "The Computer-Based Chemical Structure Information System of Merck, Sharp and Dohme Research Laboratories," Journal of Chemical Information and Computer Sciences, 16(1), 5-10 (1976). 

LIPID Membrane lipid structures Merck manual Monosaccharide database Mptopo Membrane protein topology PDB 3D structures of biomacromolecules RNA modification database RNA Structure database Spectral Database Systems (SDBS)... 

An excellent application of the Narasaka reduction is a diastereoselective synthesis by Merck scientists of 7, a structurally novel analog of the natural product compactin (8)7, which is a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase8 (Scheme 4.1e). The key step in the construction of the P-hydroxy-8-lactone moiety in 7 is the highly diastereoselective reduction of the P-hydroxy ketone 9 using a triethyl borane/sodium borohydride system. The yyn-diol 10 was obtained in high yield and with a remarkably high level of diastereoselectivity. 

A method to prepare 1,2-amino alcohols through the dihydroxylation of an enol ether has been reported by Merck (Scheme 3.25) [330]. The ee was reported to diminish if shorter chain alcohols were used although the TBDMS enol ether was used successfully in a structurally related system [331]. Indeed, early work by Sharpless with acyclic methyl and tert-butyldimethylsilyl ethers showed high en-antioselectivities in AD reactions (cf. Table 3.2) [332]. 

The Merck group s report has undoubtedly sparked the development of efficient catalytic organic reaction systems using structurally well-defined chiral organocata-lysts. Cinchona alkaloids have taken the lead in this research area, and, as a matter of course, a variety of cinchona PTCs have been newly developed and applied to diverse... 

The system, still operating to this date, is based on the approach used at the Walter Reed Army Institute of Research in Washington, D.C. The system was extensively enhanced to meet the specific needs of the Merck Sharp and Dohme Research Laboratories (MSDRL) and the Chemical Data Department (CDD) which is responsible for processing chemical structure information at Merck and Co., Inc. 

Brown, H.D. Costlow, M. Cutler, F.A. Jr. DeMott, A.N. Gall, W.B. Jacobus, D.P. Miller, C.J. The Computer-Based Chemical Structure Information System of Merck Sharp and Dohme Research Laboratories . J. Chem. Inf. Comput. Sci. 1976,16, 5-10. 

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