Interrupting the Nazarov Cyclization with Bromine

The generation of dibrominated cyclopentenones via an interrupted Nazarov cyclization is reported. The installation of two bromine atoms occurs at the α and α′ positions of the cyclopentenyl scaffold via successive nucleophilic and electrophilic bromination of the 2-oxidocyclopentenyl cation and its resulting enolate. Notably, the reaction proceeds with good diastereoselectivity, favoring the symmetrical product.本文报道了通过中断型Nazarov环化反应（interrupted Nazarov cyclization）合成二溴代环戊烯酮（dibrominated cyclopentenones）的方法。两个溴原子通过对2-氧代环戊烯正离子（2-oxidocyclopentenyl cation）及其后续生成的烯醇负离子（enolate）依次进行亲核溴代与亲电溴代反应，被安装至环戊烯母核（cyclopentenyl scaffold）的α及α′位。值得注意的是，该反应展现出良好的非对映选择性，更倾向于生成对称型产物。