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Studies on the Carbon Zip Reaction of 2‐Oxocycloalkane‐1‐carbonitriles
Author(s) -
Süsse Manfred,
Hájíček Josef,
Hesse Manfred
Publication year - 1985
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.19850680723
Subject(s) - chemistry , steric effects , ring (chemistry) , medicinal chemistry , bicyclic molecule , carbon fibers , base (topology) , reaction conditions , stereochemistry , organic chemistry , catalysis , mathematical analysis , materials science , mathematics , composite number , composite material
As a part of continuing interest in the zip reaction, we present the results on a carbon ring‐enlargement reaction of activated ketones with a CN group as a charge stabilizer. Two series of (1‐cyano‐2‐oxocy‐cloalkyl)alkanoates were prepared from 8‐ and 12‐membered cyano‐ketones 1 and 2 , respectively, namely the propanoates 3 and 4 , the butanoates 6 , 8 and 9 as well as the pentanoates 12 and 15 . While treatment with t ‐BuOK of the former two homologous esters resulted in both ring enlargement and competitive transesterification, the pentanoates 12 and 15 afforded mostly the diastereoisomeric mixtures of bicyclic alcohols 20a – c and 31a , b , respectively, which remained intact on further exposure to base. It was shown that – apart from the base used ( t ‐BuOK) vs. Li(i‐Pr) 2 N – the distribution of products was greatly influenced by the ring size of substrates. This is further illustrated by treatment of ketones 34 and 35 with t ‐BuOK. While the former rearranged smoothly to diketone 36 , no reaction at all took place with the latter. The behavior of the substrates is discussed in terms of steric and energetic reasons.