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Facile Preparation of (±)‐12‐Epiprostaglandins from 7‐Oxabicyclo[2.2.1]hept‐5‐en‐2‐one via an all‐ cis ‐formyllactone related to Corey lactone
Author(s) -
Vionnet JeanPaul,
Renaud Philippe
Publication year - 1994
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19940770710
Subject(s) - chemistry , epimer , substituent , lactone , bicyclic molecule , stereochemistry , wittig reaction , prostaglandin , biochemistry
The bicyclic monoselenoacetal 7 , easily obtained from (±)‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐one ( 6 ) via a radical addition‐acyl migration sequence, was converted to racemic 12‐epiprostaglandins 3 and 4 . The key intermediate was the all‐ cis ‐formyllactone 2b related to Corey lactone (see 12 ; Scheme 1 ). The presence of a ( tert ‐butyl)‐dimethylsilyl protective group for the 11‐OH substituent (prostaglandin numbering) was found to be crucial in avoidingβ ‐elimination and epimerization during the Wittig ‐ Horner reaction ( Scheme 2 ). Epimerization at C(12) at the formyllactone stage (see 2b ) was also possible and gave the known precursor 1b of naturally occurring prostaglandins and analogs.