Preparation of Functional Phosphorus Zwitterions from Activated Alkanes, Aldehydes, and Tributylphosphine: Synthesis of Polysubstituted Furo[3,2-c]coumarins

A general preparation of new types of highly functional phosphorus zwitterions is realized via tandem three-component reactions using the corresponding functional alkanes, aldehydes, and Bu3P. Starting from our novel zwitterions as synthetic reagents with commercially available acid chlorides in a one-step procedure provides an attractive approach toward furo[3,2-c]coumarins.