... The method of choice, particularly for the 2,3-unsubsti- (1) (a) Brown, R. T.; Joule, JA; Sammea, P. G. In Comprehensive Organic Chemistry; Barton, D. H. R., Ollis, W. D., E~E.; Pergamon Press: Oxford, 1979 Vol. 4, p 411. ... J. Org. Chem., Vol. 53, No. 6, 1988 1171 ...