Chemoselective synthesis of tetrasubstituted furans via intramolecular Wittig reactions: mechanism and theoretical analysis.

An efficient synthesis of tetrasubstituted furans was achieved from the corresponding α,ß-unsaturated ketone derivatives, acid chlorides, and Bu3P in the presence of Et3N via a chemoselective intramolecular Wittig reaction as the key step. The presence of an additional electron-withdrawing group in the α-position of Michael acceptors controlled the chemoselectivities of presumable phosphorus ylides in the intramolecular Wittig reactions, and their mechanisms were also investigated by DFT calculations.

Direct ß-acylation of 2-arylidene-1,3-indandiones with acyl chlorides catalyzed by organophosphanes.

We have developed an organophosphane-catalyzed direct ß-acylation of a series of conjugated systems bearing ketone, amide and ester functionalities using acyl chlorides as trapping reagents. A wide variety of highly functional ketone derivatives were generated efficiently under very mild conditions with high yields according to our protocol. Our adducts can even be utilized as important building blocks for the synthesis of functional tri/tetracyclic pyridazine derivatives.