An enantioselective synthetic pathway towards plakortonesDedicated to Professor Thomas C. W. Mak on the occasion of his 65th birthday.Electronic supplementary information (ESI) available: selected analytical data for compounds 2, 3 and 4 and crystal data of compounds 11, 19 and 24. See http://www.rsc.org/suppdata/cc/b2/b205924j/
On the diastereocontrol in the formation of (2R,3S)-3-(3′-furyl)-1,2-O-isopropylidenedioxy-3-pentanol and its (2R,3R)-diastereomer
摘要:
The two enantiomeric bicyclic lactone skeletons of the marine natural products plakortones, whose absolute configuration are yet unknown, are approachable from (2R,3S)-3-(3'-furyl)-1,2-O-isopropylidenedioxy-3-pentanol 1a and its (2R,3R)-diastereomer 1b. To obtain these optically pure diastereomers, two pathways were studied, in which different solvents, additives and nucleophilic reagents were employed. The stereochemistry was successfully controlled in the reaction or (2R)-1,2-O-isopropylidenedioxy-3-pentanone 3 with 3-furyllithium, which gave high syn-selectivity in Et2O. but excellent anti-selectivity in toluene. (C) 2001 Elsevier Science Ltd. All rights reserved.
作者:Xin-Gang Xie、Xun-Wei Wu、Hing-Ken Lee、Xiao-Shui Peng、Henry N. C. Wong
DOI:10.1002/chem.201000189
日期:——
Plakortone B is a naturally occurring bicyclic[3.3.0]furanolactone compound with attractive bioactivities. Although the relative configuration of plakortone B’s central core had been established by NMR spectroscopic methods, the absoluteconfiguration of its four stereocenters remained unknown. In the present paper, all four possible isomers of plakortone B were synthesized and one of these molecules
Plakortone B是一种具有吸引力的生物活性的天然存在的双环[3.3.0]呋喃内酯化合物。尽管已通过NMR光谱法确定了plakortone B中央核的相对构型,但其四个立体中心的绝对构型仍然未知。在本文中,合成了九个苦参酮B的所有四种可能的异构体,并且根据1 H,13 C NMR光谱和比旋光度的比较,发现其中一个分子与天然的九个苦参酮B相同。因此,确定天然普拉克酮B的绝对构型为(3 S,4 S,6 R,10 R)。