Complexity-building annulations of strained cycloalkanes and C═O π bonds.

This Perspective details a developing research program that emerged from simple plans for achieving the synthesis of tetrahydrofurans from cyclopropanes and C═O π bonds. Lewis acid catalyzed annulations of malonate-derived donor-acceptor cyclopropanes with aldehydes are unusually broad in scope and lead to the synthesis of structurally diverse tetrahydrofurans. The reactions are stereospecific, with inversion observed at the cyclopropane donor site.

Total synthesis of (+)-virgatusin via AlCl3-catalyzed [3+2] cycloaddition.

The AlCl(3)-catalyzed cycloaddition of a donor-acceptor (don-acc) cyclopropane and piperonal succinctly provides the core of virgatusin in a selective, high-yielding manner.

Scope and mechanism for lewis acid-catalyzed cycloadditions of aldehydes and donor-acceptor cyclopropanes: evidence for a stereospecific intimate ion pair pathway.

In this work, the one-step diastereoselective synthesis of cis-2,5-disubstituted tetrahydrofurans via Lewis acid catalyzed [3 + 2] cycloadditions of donor-acceptor (D-A) cyclopropanes and aldehydes is described. The scope and limitations with respect to both reaction partners are provided. A detailed examination of the mechanism has been performed, including stereochemical analysis and electronic profiling of both reactants.