1H-Imidazo[2,1-a]isoindole-2,5(3H,9bH)-diones 6a–i are synthesized in 67–96% yields with high stereoselectivities (de 88–99%, except 6e with a 58% de value) via intermolecular condensation of 2-formylbenzoic acid (5) and α-amino amides 4a–i in the presence of a catalytic amount of toluene-p-sulfonic acid. Intermediates 4 are obtained in two steps from easily available chiral N-Boc-α-amino acids 1.
1H-咪唑[2,1-a]异苯二酮-2,5(3H,9bH)-二酮 6a–i 的合成产率为67–96%,且具有较高的立体选择性(选择性过量为88–99%,除6e外其选择性过量为58%),通过在催化量的
对甲苯磺酸存在下,对2-甲酰
苯甲酸(5)和α-
氨基酰胺4a–i进行分子间缩合反应而实现。中间体4通过两步反应从易得的手性N-Boc-
α-氨基酸1中获得。