An Unusual Uncatalyzed Baeyer−Villiger Oxidation of Cyclobutanones to γ-Lactones by Air and Its Mechanistic Implications

Abstract

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

Differential Oxidation Conditions of Substituted Cyclobutanols Derived from Terpenes

“…Considering that two different regioisomeric c-butyrolactones could have been obtained, the chemical shifts for the methylenic carbon atoms confirmed that the reaction proceeds by a Baeyer-Villiger-like (BV) rearrangement [26] rendering 3a or 3b as a sole product. Little is known about the BV oxidation of cyclic ketones to lactones by hypochlorous acid.…”