Intermediates for the synthesis of 4-substituted proline derivatives
A chemoenzymatic synthesis of a series of 2-hydroxy-5-nitro-4-substituted esters is described that uses two biotransformations in a single-pot process in which a kinetic resolution/reduction occurs. The products are valuable intermediates for the preparation of 4-substituted prolines and 5-substituted 3-hydroxypiperidinones as illustrated by the preparation of (2R,4R)-4- methylproline and (3S,5R)-3-hydroxy-5-methylpiperidinone. Georg Thieme Verlag Stuttgart · New York.
Crosby, Stuart R.,Sessions, Richard B.,Willis, Christine L.
scheme or table
p. 539 - 542
(2010/10/02)
Isolation and structures of nostopeptolides A1, A2 and A3 from the cyanobacterium Nostoc sp. GSV224
The isolation and total structure determinations of nostopeptolides A1 (1), A2 (2) and A3 (3) are described. These cyclic depsipeptides, which are devoid of cytotoxic, antifungal and inhibition of protease activities, are characteristic constituents of the cryptophycin-producing cyanobacterium Nostoc sp. GSV224. Structure elucidation by NMR analysis was made more challenging by the existence of each nostopeptolide in three conformations. One-dimensional TOCSY experiments proved to be very useful in isolating and identifying the nine amino acid residues and the butyryl group in each compound. The absolute stereochemistries of 1-3 were determined by comparing the amino acids in the acid hydrolyzates directly with authentic standards. (C) 2000 Elsevier Science Ltd.
Golakoti, Trimurtulu,Yoshida, Wesley Y.,Chaganty, Sreedhara,Moore, Richard E.
p. 9093 - 9102
(2007/10/03)
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