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Photolyse von 2, 2, 4, 4‐Tetramethylcyclobutanon‐Derivaten
Author(s) -
Hostettler H. U.
Publication year - 1966
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.19660490802
Subject(s) - chemistry , cyclopropane , decarbonylation , double bond , carbene , ring (chemistry) , medicinal chemistry , alkyl , photochemistry , stereochemistry , organic chemistry , catalysis
The photochemical reactions of the 2, 2, 4, 4‐tetramethylcyclobutanones 1–6 carrying various substituents in 3‐position were investigated. The major reaction in alcoholic solution or in the presence of other protic compounds was the formation of the semicyclic acetals 7–12 . Parallel to this reaction decarbonylation occurred, leading to stable cyclopropane derivatives in some cases, depending on the substituents present. Cyclopropanes with an exocyclic double bond underwent ring opening easily or, in case of an exocyclic carbon‐nitrogen double bond, added alcohol, thus forming cyclopropane O, N‐ketals. Alkyl‐acyl biradicals are proposed as common intermediates for both photoreactions. Based on analogy to similar photoreactions reported in the literature, the formation of the semicyclic acetals is assumed to involve a carbene intermediate.