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Synthesis of (23 R )‐ and (23 S )‐23 H ‐Isocalysterols, Marine Sterols with a Cyclopropene Moiety in the Side Chain
Author(s) -
KurekTyrlik Alicja,
Minksztym Kazimierz,
Wicha Jerzy
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(200003)2000:6<1027::aid-ejoc1027>3.0.co;2-e
Subject(s) - chemistry , vinylsilane , alkylation , side chain , moiety , cyclopropene , diastereomer , nitrile , bromide , stereochemistry , cyclopropanation , total synthesis , organic chemistry , catalysis , polymer
A synthesis of (23 R )‐ and (23 S )‐23 H ‐calysterols 2a and 2b from pregnanoic ester 10 is reported. Alkylation of 10 with dibromide 19b , followed by reduction of the carboethyloxy group to a methyl group, afforded ( Z )‐vinylic bromide 22 . Dibromocyclopropanation of 22 yielded the diastereomeric tribromocyclopropane derivatives 15c and 15d . The corresponding 3‐hydroxy‐5‐ene 17c was transformed into 2a via 25 and a cyclopropenyllithium intermediate. An alternative synthetic route involving vinylsilane 13 and ( E )‐vinylic bromide 14 has also been examined.