Photochemical rearrangement of .alpha.,.beta.-epoxy ketones. Elaboration of the mechanism

Photochemical, thermal, and acid-catalyzed rearrangements of .alpha.,.beta.-epoxy ketones. Synthesis of spiro .beta.-diketones

“…Since the keto acids had melting points near room temperature and were difficult to recrystallize, their methyl esters were prepared. Again the authentic methyl ester 11 showed different spectral properties from those of the ester obtained from the hydrolysis product. Therefore, what is the structure of the hydrolysis product and that of the 8-diketone from which it is derived?…”

Photochemistry of Steroids

“…In later studies of the mechanism of this reaction, a biradical 1,2-alkyl shift without epimerization at C-4 or C-10 was postulated (11,12). In contrast to these reactions, irradiation of epoxyketones 111, IV, V, and VI, in which the epoxy and/or keto groups are in different positions, gave 1,3-diketones, ring-contracted compounds, and a carboxylic acid ( I 3) ( Table I).…”

3.16 The Semipinacol Rearrangements

“…Photochemical rearrangement of 2,3-epoxy ketones has also been attempted, which usually gives 3,2-migration products on special epoxy opening at 2-position (Scheme 132). 179 These type of reactions also feature an unusual order for the migration aptitude of substituents at 3-position, namely benzhydryl and benzyl4hydrogen4methylene4methylcphenyl.…”