An AgOAc-catalyzed reaction of 3-nitro-2H-chromenes with ethyl diazoacetate: an efficient one-pot synthesis of ethyl 3,4-dihydrochromeno[3,4-c]pyrazole-1-carboxylates

A regioselective method for the synthesis of ethyl 3,4-dihydrochromeno[3,4-c]pyrazole-1-carboxylates from 2-substituted 3-nitro-2H-chromenes and ethyl diazoacetate in 68-87% yields was developed. This approach involves an AgOAc-catalyzed 1,3-dipolar cycloaddition of ethyl diazoacetate to nitrochromenes followed by elimination of HNO2 by the action of DBU.

Automated summary

A regioselective method for the synthesis of ethyl 3,4-dihydrochromeno[3,4-c]pyrazole-1-carboxylates from 2-substituted 3-nitro-2H-chromenes and ethyl diazoacetate was developed with high yields. This approach involves a 1,3-dipolar cycloaddition catalyzed by AgOAc followed by elimination of HNO2 with DBU.