Formals, diaryl synthesis

A high yield synthesis involving formal oxidation of a sulphoxide to a sulphoximine has been reported183 using O-mesitylenesulphonyl hydroxylamine (NH2OMes) (equation 67). The reaction is successful for a wide range of sulphoxides including dialkyl, diaryl and cyclic species. 

A different sequential DreM pathway involving O-carbamate ring switch-vinylogous tolyl amide cydization, 170 —> 171 —> 172 (Scheme 44), a formal bridging of a 2,2 -methyl diaryl dicarbanion with a carbonyl dication equivalent (173) has been affirmed in a model study (174 —> 175, Scheme 45) [73] and applied in natural product total synthesis [73, 74]. 

In 1974, McKillop and co-workers reported the formation of diphenox3nnethane derivatives from the attempted alkylation of p-Jt-butylphenol with benzyl chloride and a catalytic amount of a phase transfer catalyst (PTC) in methylene chloride. More recently, Dehmlow and Schmidt reported the synthesis of a series of dlalkyl and diaryl formals ( from the reaction of alkoxide and phenoxide anions with methylene chloride in the presence of a phase transfer catalyst (equation 5). For example, reaction of 2,3,5-trimethylphenol, powdered potassium hydroxide... 

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