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Synthesis of Cembranolides by S E ′ Cyclization of Enantioenriched α‐Alkoxy Allylstannanes
Author(s) -
Marshall James A.,
Gung Benjamin W.
Publication year - 1991
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199100023
Subject(s) - chemistry , alkoxy group , stereochemistry , organic chemistry , medicinal chemistry , alkyl
A total synthesis of the unnamed cembranolide 35 is described starting from enal XV , an intermediate derived from geraniol. Key transformations include asymmetric reduction of stannyl ketone 1 with ( R )‐(+)‐BINAL‐H to give the hydroxy stannane 2 of high ee, and cyclization of the derived MOM ether 6 to the cis ‐( Z ) hydroxy enol ether 7 in high yield. Further elaboration of 7 to the natural product was achieved by OH‐directed hydroalanation‐iodination of the derived diol 17 , methylation of iodide 17 with methyl cuprate and selective protection, oxidation, lactonization, and α‐methylenation. The resulting product was identified by comparison of 1 H NMR, 13 C NMR, IR, and optical rotation with an authentic sample. The synthesis defines the absolute configuration of the natural cembranolide.