K₂CO₃ Promoted Spirocyclopropanation of Thiazole-Derived Oxadienes via 1,4-Addition-Induced Dearomatization Reaction

A K2CO3 promoted spirocyclopropanation of thiazole-derived oxadienes with bromomalonate via 1, 4-addition-induced dearomatization strategy has been developed. The pathway features a broad substrate scope, operational simplicity and high degree of synthetic efficiency to afford series of functionalized spiro-cyclopropanation frameworks in 88 %-96 % yields, which enriches the research contents of thiazole-derived oxadienes involved reactions. All products obtained herein contain two contiguous quaternary centers and their further synthetic applications are also demonstrated.