Time-resolved IR detection and study of an iminooxirane intermediate

Iminooxirane 4 has been generated by the reaction of phenylchlorocarbene (2) with phenyl isocyanate (3) and studied by nanosecond timere-solved infrared spectroscopy. Iminooxirane 4 (1830 cm(-1)) isomerizes to alpha-lactam 5 (1880 cm(-1)) at an observed rate of 3 X 10(4) s(-1). Peak assignments were confirmed by a combination of B3LYP calculations and isotopic labeling. An acyclic transition state was found computationally for the isomerization reaction.