When the combination of zinc triflate and chlorotrimethylsilane is substituted for a Brønsted acid, the classic Passerini reaction of carbonyl compounds with t-butyl isonitrile affords an efficient 1:2 condensation product leading to β-hydroxy-α-cyanoenamines 17a-f, which can be transformed into 5-substituted-4-cyanooxazoles 8a-f in one step. In contrast to the corresponding Ti-mediated condensations of carbonyl compounds with t-butyl isonitrile, no cyanohydrins are formed.
当使用
三氟甲磺酸锌与
氯三甲基
硅烷的组合替代布朗斯特酸时,羰基化合物与特丁基异
氰化物的经典Passerini反应能够高效地生成1:2缩合产物,即β-羟基-α-
氰基烯胺17a-f,这些物质可以通过一步反应转化为5-取代-4-
氰基
噁唑8a-f。与相应的
钛催化的羰基化合物与特丁基异
氰化物的缩合反应相比,没有生成
氰醇。