Dunn JA, Stradiotto M, McGlinchey MJ
Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1 Canada.
J Org Chem. 2000 Aug 11;65(16):4861-3. doi: 10.1021/jo000125m.
The Diels-Alder reaction of tetracyanoethylene (TCNE) with 1, 4-diethyl-5-(trimethylsilyl)ethynyl-2,3-diphenylcyclopentadien-5-ol (3a) occurs on the hydroxyl-bearing face of the diene and yields ultimately an imino lactone (5a), whereby the hydroxyl functionality has added across an exo nitrile linkage. TCNE and 5-(trimethylsilyl)ethynyl-1,2,3,4-tetraphenylcyclopentadien-5-ol (3b) behave analogously. In contrast, the [4 + 2] adduct of 3b with dimethyl acetylenedicarboxylate (DMAD) undergoes a dramatic skeletal rearrangement to generate the 1,4-cyclohexadiene (9) in which an alkynyl ketone moiety has migrated onto an ester-bearing carbon. The molecules 5a and 9 have been characterized by X-ray crystallography, and a mechanism for the skeletal rearrangement is proposed.
四氰基乙烯（TCNE）与1,4 - 二乙基 - 5 -（三甲基甲硅烷基）乙炔基 - 2,3 - 二苯基环戊二烯 - 5 - 醇（3a）的狄尔斯 - 阿尔德反应发生在二烯含羟基的面上，最终生成一种亚氨基内酯（5a），其中羟基官能团通过外环腈键加成。TCNE与5 -（三甲基甲硅烷基）乙炔基 - 1,2,3,4 - 四苯基环戊二烯 - 5 - 醇（3b）的反应类似。相比之下，3b与二甲基乙炔二羧酸酯（DMAD）的[4 + 2]加合物发生了剧烈的骨架重排，生成了1,4 - 环己二烯（9），其中炔基酮部分迁移到了含酯基的碳上。分子5a和9已通过X射线晶体学进行了表征，并提出了骨架重排的机制。
