Synthesis of Cyclopentenones through Rhodium-Catalyzed C-H Annulation of Acrylic Acids with Formaldehyde and Malonates

An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones based on a three-component reaction of acrylic acids, formaldehyde, and malonates via vinylic C-H activation is reported. Exploratory studies showed that 5-alkylation of asprepared cyclopentenones could be realized smoothly by the treatment of a variety of alkyl halides with a Na2CO3/MeOH solution. Excess formaldehyde and malonate led to a multicomponent reaction that afforded the multisubstituted cyclopentenones through a Michael addition.

Automated summary

An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones based on a three-component reaction of acrylic acids, formaldehyde, and malonates was reported. The treatment of a variety of alkyl halides with a Na2CO3/MeOH solution could smoothly achieve 5-alkylation of the cyclopentenones. Excess formaldehyde and malonate led to a multicomponent reaction that afforded multisubstituted cyclopentenones through a Michael addition.