Stereochemistry of decarbalkoxylation of cyclic geminal diesters effected by water and lithium chloride in dimethyl sulfoxide
Stereochemistry of decarbalkoxylation of cyclic geminal diesters effected by water and lithium chloride in dimethyl sulfoxide
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DOI：
10.1021/jo01309a007
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发表时间：
1980-10
影响因子：
3.6
通讯作者：
A. Krapcho;J. Weimaster
中科院分区：
文献类型：
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作者：
A. Krapcho;J. Weimaster
考察了LiCl-H20-Me_2S_0对环状双甘酯脱碳的立体化学影响。降冰片烯双酯13和降冰片烯双酯16分别主要通向外酯14和17。2-甲基环己烷二酯22导致含有更多顺式(23)比反式(24)异构体的酯。双酯19、25和28产生几乎等量的顺式和反式酯。在后一种情况下，由酯(通过LDA)产生的烯醇化产物在用水淬火时以非立体选择性的方式质子化。这表明脱碳反应中有一种烯醇中间体。对这些立体化学结果的意义进行了讨论。在过去十年左右的时间里，我们报道了丙二酸酯1到2(以及相关的/3-酮酸酯和-氰酸酯)在Me2SO水溶液和其他偶极非质子溶剂中的脱碳氧基化合成应用的研究。2.
The stereochemical consequences of the decarbalkoxylation of cyclic geminaldiesters by LiCl-H20-Me2S0 have been examined. The norbornene diester 13 and the norbornane diester 16 lead predominantly to the exo esters 14 and 17, respectively. The 2-methylcyclohexane diester 22 leads to esters containing more cis (23) than trans (24) isomer. The diesters 19, 25, and 28 leadto nearly equal amounts of the cis andtrans esters. In these latter cases, the enolates generated from the esters (via LDA) are protonated in a nonstereoselective fashion on quenching with water. This is suggestive of an enolate intermediate in the decarbalkoxylation reaction. The implications of these stereochemical results are discussed.Over the past decade or so we have reported studies of the synthetic applications of the decarbalkoxylations of malonate esters 1 to esters 2 (and the related/3-keto esters and-cyano esters) using various salts in aqueous Me2SO and other dipolar aprotic solvents. 2