SnCl4-Promoted [3+2] Annulation of γ-Butyrolactone-Fused Donor-Acceptor Cyclopropanes with Nitriles: Access to γ-Butyrolactone-Fused 1-Pyrrolines.

The [3+2] annulation of γ-butyrolactone-fused donor-acceptor cyclopropanes with nitriles has been explored for the access of γ-butyrolactone-fused 1-pyrrolines. The annulation was promoted by tin(IV) chloride, and the products were obtained as single diastereomers in moderate to good yields. The products were synthetically important, and a couple of them were subjected to tandem reductive ring opening/cyclization to give the respective γ-butyrolactone-fused γ-butyrolactams in good yields.