Trifluoromethanesulfonic (triflic) acid catalyzed transformations of .alpha.-hydroxy carbonyl compounds
摘要:
Triflic acid catalyzed reaction of 2-hydroxy-2-adamantanecarboxylic acid results via ionizative decarbonylation in the formation of adamantonone. Under carbon monoxide pressure pinacol-type rearrangement gives 4,5-homoadamantanedione. Reaction of a series of alpha-hydroxy ketones result in fragmentation, deprotonation, and cyclization, respectively. The reactions and their suggested mechanism are discussed.
F−-Induced decomposition of 3-[(3-tert-butyldimethylsiloxy)phennoxy]-3-phenyl-1,2-dioxetanes without CC bond cleavage of the dioxetane ring
摘要:
F--induced decomposition of 3-[3-(tert-butyldimethylsiloxy)phenoxy]-3-phenyl-1,2-dioxetane (5c) yielded an intramolecular redox product (7b), whereas 3-phenoxy-3-(3-siloxyphenyl)-1,2-dioxetane (3) gave normal carbonyl fragments with intense light emission. An isomer (5a) gave Light with normal decomposition by CIEEL, though the major process was one to yield an acyloin (7a). (C) 1997 Elsevier Science Ltd.
Isolated methyl trifluoromethyl dioxirane 4b has been employed to achieve the rapid, low temperature epoxidation of enolethers, such as alkoxy(aryl)methylidene adamantanes 1a–e and methoxy(2-naphthyl)methylidene 2-bornane 1f, affording the corresponding spirooxiranes in excellent (92–97%) yields.