KOBu-promoted Michael/aldol/ring-opening cascade reaction of cyclobutanones with chalcones.

An efficient Michael/aldol/ring-opening cascade reaction of cyclobutanones with chalcones has been developed. This protocol employs inexpensive potassium -butoxide (KOBu) as a promoter and enables an efficient synthesis of densely substituted cyclohex-3-ene-carboxylic acids in high yields with high diastereoselectivities, which are difficult to prepare through conventional approaches. The significant advantages of this methodology include transition-metal-free conditions, readily available starting materials, wide scope and high atom economy.