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Stereoselective Synthesis of (+)‐Nephrosteranic Acid, (+)‐ trans ‐Cognac Lactone, and (+)‐ trans ‐Whisky Lactone using a Chiral Cyclohexadienyl Ti Compound
Author(s) -
Schleth Florian,
Vogler Thomas,
Harms Klaus,
Studer Armido
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400237
Subject(s) - chemistry , stereoselectivity , desymmetrization , lactone , lewis acids and bases , organic chemistry , derivative (finance) , stereochemistry , enantioselective synthesis , catalysis , financial economics , economics
We present the stereoselective transfer of cyclohexadienyl from 3‐metalated 1,4‐cyclohexadienes to various aldehydes. Lewis‐acid‐mediated “allylation” of aldehydes by treatment with 3‐silylated and 3‐stannylated 1,4‐cyclohexadienes could not be achieved with high diastereoselectivity. In contrast, cyclohexadienyl titanium compounds reacted with both aliphatic and aromatic aldehydes with good‐to‐excellent diastereoselectivities. Reaction of a chiral TADDOL‐derived (TADDOL, 2,2‐dimethyl‐α,α,α′,α′‐tetraphenyl‐1,3‐dioxolandimethanol) cyclohexadienyl Ti derivative with various aldehydes led to the corresponding homoallylic alcohols with excellent diastereo‐ and enantioselectivities. Lower selectivities were obtained with chiral B ‐cyclohexadienyldiisopinocampheylborane. The 1,3‐cyclohexadienes are very useful building blocks for the preparation of biologically important γ‐butyrolactones. Short efficient syntheses of (+)‐nephrosteranic acid, (+)‐ trans ‐whisky lactone, and (+)‐ trans ‐cognac lactone by desymmetrization of 1,4‐cyclohexadiene are described.