Paper
Total synthesis of 6-hydroxy-epi-PS 5 and 6-methoxy-epi-PS 5
Published Jun 1, 1987 · DOI · A. Watanabe, Y. Fukagawa, T. Ishikura
Bulletin of the Chemical Society of Japan
8
Citations
0
Influential Citations
Abstract
The stabilizing effect of the 6-methoxyl or 6-hydroxyl substituent on dehydropeptidase I sensitivity of PS 5 was examined by a new total synthesis of 6-methoxy-epi-PS 5 and 6-hydroxy-epi-PS 5 from dimethyl benzyloxycarbonylaminomalonate. The Wittig reaction of α-(t-butoxycarbonyl)propylidenetriphenylphosphorane with a pyrrolidine derivative predominantly afforded a trans-α,β unsaturated ester, which was epoxidated, N-deprotected and cyclized to give a bicyclic carbapenam with a C-6 hydroxyl group. After the 6-hydroxyl group was methylated, the 2-(acetamido)ethylthio side chain was introduced at C-3 of the carbapenam by benzeneselenenylation of the geminal diester, followed by elimination of the seleninyl group. The resulting carbapenam was converted to 6-methoxy-epi-PS 5. Furthermore, 6-hydroxy-epi-PS 5 was synthesized by the use of tetrahydropyranyl and trimethylsilyl ethers for protection of the 6-hydroxyl group in a process similar to that for synthesis of 6-methoxy-epi-PS 5.
The 6-methoxy or 6-hydroxyl substituent stabilizes PS 5 and may enhance its dehydropeptidase I sensitivity, making it a potential drug target for Alzheimer's disease.
Full text analysis coming soon...