Bis(trimethylsilyl) Sulfate Catalysis in γ-Lactonization of Cyclopropanecarboxylates Activated by Carbonyl Substituents on α-Carbon
作者:Yoshitomi Morizawa、Tamejiro Hiyama、Koichiro Oshima、Hitosi Nozaki
DOI:10.1246/bcsj.57.1123
日期:1984.4
The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)–C(2) bond cleavage to produce γ-lactones. Stereochemically, the reaction takes two pathways: (1) substrates with a cationstabilizing group like vinyl on C(2) give thermodynamically favored γ-lactones having the thermodynamically more stable arrangement of substituents irrespective of the configuration of the cyclopropane substrates, (2) substrates without such a cation-stabilizing group afford γ-lactones under ca. 70% inversion at C(2) reaction center.
在 C(1)-C(2) 键裂解的作用下,1-羰基取代的环丙烷羧酸盐发生标题反应,生成 γ-内酯。从立体化学角度看,反应有两种途径:(1) 底物的 C(2)键上带有阳离子稳定基团(如乙烯基),无论环丙烷底物的构型如何,都会产生热力学上更稳定的取代基排列的γ-内酯;(2) 底物不带有阳离子稳定基团,在 C(2) 键约 70% 的反转作用下产生γ-内酯。C(2)反应中心 70% 的反转作用下生成γ-内酯。