Page 1. Tetrahedron Letters,Vo1.23,Fo.44,pp 4535-4538,1982 0040-4039/82/444535-04$03.00/ o Printed in Great Britain ... For reviews of the literature, see: (a) K. Schaffner and M. Demuth, Essay 18 in "Rearrangements of Ground and Excited States", Vol. ...