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syn ‐Diastereoselective Homoaldol Reactions: γ‐Hydroxyalkylation of ( Z )‐2‐Butenyl Carbamates and Synthesis of β,γ‐ cis ‐Di‐ and ‐Trisubstituted γ‐Lactones
Author(s) -
Hoppe Dieter,
Lichtenberg Florian
Publication year - 1984
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.198402391
Subject(s) - lactol , chemistry , stereoselectivity , diastereomer , lactone , ether , stereochemistry , aldehyde , medicinal chemistry , organic chemistry , catalysis
The preparation of the syn ‐homoaldol derivatives syn ‐3 in ≥ 85% stereoselectivity is achieved by reaction of the lithiated ( Z )‐2‐butenylcarbamate 1 , X OC(O)N( i Pr) 2 , M Li, with aldehydes or ketones. Previously, only access to anti ‐diastereomers was possible. Mercury( II )acetate‐catalyzed methanolysis of syn ‐ 3 furnishes a cis ‐γ‐lactol methyl ether: the relative configurations at C‐3 and C‐4 are retained. Subsequent oxidation leads to lactones, e.g. to (±)‐quercus‐lactone b.