P. Wan et al., 1995 MERCK-FROSST-AWARD-LECTURE - QUINONE METHIDES - RELEVANT INTERMEDIATES IN ORGANIC-CHEMISTRY, Canadian journal of chemistry, 74(4), 1996, pp. 465-475
ortho and para-Quinone methides (2-methylene-3,5-cyclohexadien-1-one a
nd 4-methylene-2,5-cyclohexadien-1 one, respectively) are intermediate
s in a variety of important chemical systems. In particular, o-quinone
methides are useful in synthesis for the construction of chroman ring
systems. A brief account of the relevance of quinone methide chemistr
y will be provided. This is followed by a review of recent studies fro
m our laboratory on efficient methods for the photogeneration of quino
ne methides, concentrating on the use of hydroxy-substituted benzyl al
cohols in aqueous media. It is shown that this method is general since
it provides access to o-, m-, and p-quinone methide isomers. When app
ropriately substituted, all of these quinone methide isomers have been
spectroscopically characterized by laser flash photolysis, making thi
s technique the one of choice for studying the dynamics of these react
ive intermediates. The mechanism of photochemical generation from hydr
oxybenzyl alcohols and extensions of the reaction to photogeneration o
f fluorenyl and biphenyl quinone methides will also be presented.