Reaction of dienamine 2 (R = H and Me) with
N
-phenylmaleimide or chromone 3 gives xanthones 5 and
8, respectively, through initial [4 + 2] cycloaddition,
whereas reaction with dimethyl acetylenedicarboxylate affords xanthone
13.
二胺 2(R = H 和 Me)与 N-苯基马来
酰亚胺或
色酮 3 反应,通过初始 [4 + 2] 环加成分别得到呫吨 5 和 8,而与
乙炔二
羧酸二甲酯反应则得到呫吨 13。