Visible light mediated, metal-free carbene transfer reactions of diazoalkanes with propargylic alcohols.

The development of efficient carbene transfer reactions under mild reaction conditions is very important to access small molecules for applications in organic synthesis and drug discovery. Herein, we describe the application of blue light in photochemical carbene transfer reactions of donor acceptor diazoalkanes under mild reaction conditions with propargylic alcohols, which provides - in contrast to conventional metal-catalyzed carbene transfer reactions - an access to cyclopropenes.