摘要：

General methods have been developed for the ortho alkylation and the ortho formylation of phenols. The processes are based on the rearrangement of ylides formed from the treatment of oxasulfonium salts with triethylamine. The oxasulfonium salts were prepared through the reaction of a phenol with either a chlorosulfonium chloride or an S-(N-succinimido)sulfonium chloride and used in situ. The intramolecular rearrangement of the ylides in a [2,3]-sigmatropic manner led to exclusive ortho substitution via an intermediate cyclohexadienone. Hydrogen transfer and accompanying rearomatization of the cyclohexadienone gave a phenol with sulfur in the side chain. Raney-nickel reduction gave an ortho-alkylated phenol. When dithiane was used as the sulfide, hydrolysis of the ortho-substituted product gave an ortho-formylated phenol. Alternatively, ortho formylation could be accomplished through an efficient process involving α-chlorination of an o-methylthiomethy lphenol with N-chlorosuccinimide, followed by hydrolysis. A general discussion of the utility and mechanistic details of these reactions is given below.

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