... The singlet states of these systems react by u-bond cleavage of the ring to give products which are explicable in terms of the chemistry of vinyl carbenes. ... 1979, 100, 5743. 0002-7863/81/1503- 3057SO1.2510 I , , 0 1981 American Chemical Society Page 2. ... SOC., Vol. 103, No. 11. ...