Organocatalytic Enantioselective Formal (4 + 2)-Cycloadditions of Phosphine-Containing Dipoles with Isocyanates
作者:Xuling Chen、Tao Wang、Zhongyue Lu、Pengfei Li
DOI:10.1021/acs.orglett.2c01154
日期:2022.4.29
Phosphine-catalyzed enantioselective formal (4 + 2)-cycloadditions of 2-(4H-benzo[d][1,3]oxazin-4-yl)acrylates with isocyanates have been developed for the first time. The initial SN2′ attack of the chiral phosphine organocatalyst on 2-(4H-benzo[d][1,3]oxazin-4-yl)acrylates generated the key phosphine-containing dipolar intermediates, and the subsequent formal cycloaddition with isocyanates furnished
首次开发了膦催化的 2-(4 H-苯并[ d ][1,3]恶嗪-4-基)丙烯酸酯与异氰酸酯的对映选择性形式 (4 + 2)-环加成反应。手性膦有机催化剂对 2-(4 H-苯并[ d ][1,3]oxazin-4-yl) 丙烯酸酯的初始 S N 2' 攻击产生了关键的含膦偶极中间体,随后与异氰酸酯以 60-84% 的收率和 61-92% 的 ee 提供范围广泛的 3,4-二氢喹唑啉-2-酮。