Efficient synthesis of benzothieno[3,2-<i>d</i>]-imidazo[1,2-<i>a</i>]pyrimidine-2,5-(1<i>H</i>, 3<i>H</i>)-diones<i>via</i>a tandem aza-wittig/heterocumulene-mediated annulation
作者:Sheng-Zhen Xu、Jing Wu、Min-Hui Cao、Ming-Wu Ding
DOI:10.1002/jhet.258
日期:——
Carbodiimide , obtained from aza-Wittig reaction of iminophosphorane with aromaic isocyanate, reacted with α-amino ester in the presence of catalytic amount of sodium ethoxide to give selectively new tetracyclic benzothieno[3,2-d]-imidazo[1,2-a]pyrimidine-2,5-(1H, 3H)-diones in good yields. X-Ray structure analysis of verified the proposed structure and the reaction selectivity. J. Heterocyclic Chem