cyclopropane derivative was introduced in the segment of cepaciamide A. The formation of (Z)-olefin in the segment of cepaciamide B was achieved by means of partial reduction of the acetylenic bond. Esterification between the fatty acid-segments and the amide-segment with DCC/DMAP and subsequent oxidative deprotection of the MPM group with CAN gave cepaciamides.
Total syntheses of cepaciamides A and B were accomplished. In the preparation of two fatty acid segments, (S)-malic acid was used as a chiral source to introduce (2S)-configuration. A known chiral cyclopropane derivative was introduced in the segment of cepaciamide A. The formation of (Z)-olefin in the segment of cepaciamide B was achieved by means of partial reduction of the acetylenic bond. Esterification
Asymmetric synthesis of nucleosides was achieved via the intermediate 2,3-endo-methylene pentofuranoyl chloride 6, which was prepared from 1 with high stereoselectivity (only α chlorosugar). The SN2 type condensation of 6 with sodium salt of adenine and silyated N4-benzoylcytosine gave the desired β-nucleosides as major isomers (β:α = 2.5:1 and 2:1, respectively).
Study on fungitoxic 3-amino-2-piperidinone-containing lipids: Revised structure of cepaciamide A and structural determination of its closely related lipid, cepaciamide B
The structure of cepaciamide A was revised to be (3R,3'S,2"S,11"S,12"R)-3-[3'-(2"-hydroxy-11", 12"-methyleneoctadecanoyloxy)hexadecamido]-2-piperidinone with respect to the absolute configuration of the C-3'- and C-2"-positions and the position of the cyclopropane ring by using synthetic methods. The structure of cepaciamide B was also determined to be (3R,3'S,2"S,11"Z)-3-[3'-(2"-hydroxy-11"-octadecenoyloxy)hexadecamido]-2-piperidinone. (C) 1999 Elsevier Science Ltd. All rights reserved.