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An Unusual Uncatalyzed Baeyer−Villiger Oxidation of Cyclobutanones to γ‐Lactones by Air and Its Mechanistic Implications
Author(s) -
Singh Rajinder,
Ishar Mohan Paul S.,
Girdhar Navdeep K.,
Velmurugan Devadasan,
Pandi A. Subbiah
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200211)2002:22<3734::aid-ejoc3734>3.0.co;2-k
Subject(s) - chemistry , baeyer–villiger oxidation , aryl , substituent , ring (chemistry) , performic acid , medicinal chemistry , halogen , stereochemistry , organic chemistry , catalysis , alkyl
The cyclobutanone moieties in 5‐aryl‐7,11,11‐trimethyltricyclo[5.4.0.0 3,6 ]undec‐1‐en‐4‐ones 4a − e undergo an unusual, uncatalyzed Baeyer−Villiger (BV) oxidation when their methanolic solutions are exposed to air at room temperature for 45 d, quantitatively producing mixtures of γ‐lactones ( 5a − e , 6a − e ); the ratio 5 / 6 varies with the nature of the substituent on the aryl ring (9:1 to ca. 1:1). BV oxidations of 4a − c and 4e with H 2 O 2 and of 4c − d with performic acid have also been carried out, and the results are compared with those of air oxidation; in the latter case an unusual enhancement of the migratory aptitude of a benzylic carbon atom, in a BV oxidation, by the presence of halogen substituents on the aryl ring is observed. A mechanistic interpretation of the obtained results is proposed. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)