Intramolecular Chirality Transfer [2 + 2] Cycloadditions of Allenoates and Alkenes.

Intramolecular chirality transfer [2 + 2] cycloaddition of enantiomerically enriched allenoates and alkenes is presented. The use of a chiral catalyst was found to be critical to achieve high levels of diastereoselectivity compared to use of an achiral catalyst. The method developed leads to highly substituted cyclobutanes that would be difficult to prepare by alternative methods.