Neighboring group participation in carbene chemistry. Effect of neighboring carboxylate group on carbene reactivities
作者:Hideo Tomioka、Katsuyuki Hirai、Kazuo Tabayashi、Shigeru Murata、Yasuji Izawa、Satoshi Inagaki、Takehiko Okajima
DOI:10.1021/ja00177a033
日期:1990.10
the relative reactivities (k OH /k add ) being 0.3-0.5. In marked contrast, the «carboxylate» carbene generated from the sodium salt of the diazoacetate under the same conditions produces mostly the OH insertion product at the expense of the cyclopropanes, k OH /k add being >100. The marked effect of the carboxylate group is nicely explained in terms of the participation by the neighboring carboxylate
(烷氧基羰基)卡宾的反应性显示出显着变化,因为一个人用羧酸酯基团取代了酯基团。因此,(甲氧基羰基)-或羧基(4-硝基苯基)卡宾,通过相应的重氮化合物在 2-甲基-2-丁烯和甲醇的二元混合物中的光解产生,将环加成产物提供给丁烯,而 OH 将产物插入到甲醇,相对反应性(k OH /k add )为0.3-0.5。与此形成鲜明对比的是,在相同条件下由重氮乙酸钠盐生成的“羧酸盐”卡宾主要产生 OH 插入产物,但会消耗环丙烷,k OH /k add 大于 100。羧酸根的显着效果很好地解释了相邻羧酸根的参与,