Reaction of ketene-S, N-acetals (1a-c) derived from lactams with dimethyl acetylenedicarboxylate (DMAD) gave the ring-expanded products (3a-c, respectively). On the other hand, similar treatment of N-acetyl ketene-S, N-acetals (5b, c) afforded the [2+2] adducts (6b, c, respectively). Next, the reaction of benzoketene-S, N-acetals (8a-c) with DMAD furnished the ringopened products (13a-c, respectively).
来自内酰胺的酮烯-S,N-
乙缩醛(1a-c)与二甲基
乙炔二
羧酸酯(
DMAD)反应,得到了环扩张产物(3a-c,分别对应)。另一方面,N-乙酰基酮烯-S,N-
乙缩醛(5b,c)经过类似处理,形成了[2+2]加合物(6b,c,分别对应)。随后,苯并酮烯-S,N-
乙缩醛(8a-c)与
DMAD反应,生成了开环产物(13a-c,分别对应)。