New substituent effects of the trimethylsilyl group: photochemistry of 3-trimethylsilyl-2,5-cyclohexadienones and preparation of 4-alkylidenecyclopentenones.
New substituent effects of the trimethylsilyl group: photochemistry of 3-trimethylsilyl-2,5-cyclohexadienones and preparation of 4-alkylidenecyclopentenones.
复制标题
三甲基甲硅烷基的新取代基效应：3-三甲基甲硅烷基-2,5-环己二酮的光化学和4-亚烷基环戊烯酮的制备。
DOI：
10.1021/jo000209v
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
LockwoodJr,LO
中科院分区：
文献类型：
--
作者：
Schultz,AG;LockwoodJr,LO
The 4-acetoxymethyl-4-alkyl-3-trimethylsilyl-2,5-cyclohexadien-1-ones9a−gwere prepared from methyl 2-trimethylsilylbenzoate by the Birch reduction−alkylation reaction. Type A photorearrangements of9a−gwere regiospecific to give mixtures of two diastereomers of the corresponding 5-trimethylsilylbicyclo[3.1.0]hex-3-en-2-ones11a−g. These bicyclohexenones are uniquely photostable; the diastereomers do not photointerconvert nor do they undergo the type B photorearrangement. Bicyclohexenones11a−gundergo acid-catalyzed protiodesilylative rearrangement to give the 4-alkylidene-2-cyclopenten-1-ones25a−g. It was of interest to find that the 4-(3‘-butenyl)-2,5-cyclohexadienone9ephotorearranged to the 5-trimethylsilylbicyclo[3.1.0]hex-3-en-2-one11erather than undergoing the intramolecular 2 + 2 photocycloaddition. Furthermore, the 4-acetoxymethyl-3-methoxy-4-methyl-5-trimethylsilyl-2,5-cyclohexadienone30adid not show type A photobehavior at 366 and 300 nm, while the 4-(3‘-butenyl) analogue30bgave the intramolecular 2 + 2 cycloadduct31b. The effects of the trimethylsilyl and methoxy substituents on the photochemical reactivity of 2,5-cyclohexadien-1-ones are discussed from the perspective of n → p* vs π → p* character of the triplet states of the dienones.
