Carbohydrates as Chiral Auxiliaries. [2+2) Cycloadditions of Ketenes to Enol Ethers

All articles of this category Enantiomerically pure cyclobutanols containing up to four chiral centers were synthesized applying a [2+2] cycloaddition between carbohydrate enol ethers and substituted ketenes. Acid-catalysed cleavage of the anomeric acetal linkage to the carbohydrate auxiliary gave (1R,2R,3S)-3-benzyloxy-2-methylcyclobutanol in high yield and under conservation of all generated chiral centers. The absolute configuration of the synthesized cyclobutanols was determined by single-crystal X-ray analysis.