Ultrafast UV-Visible and Infrared Spectroscopic Observation of a Singlet Vinylcarbene and the Intramolecular Cyclopropenation Reaction

摘要

Singlet carbenes are reactive intermediates that undergo unique inter- and intramolecular reactions.' Intermolecular reactions of arylcarbenes have been studied extensively. Vinylcarbenes undergo intramolecular cyclization to form cyclopropenes. Triplet vinylcarbene has two geometric isomers which have been detected by matrix isolation spectroscopy. Calculations indicate that singlet vinylcarbene resides 12-13 kcal/mol above the triplet ground state.