Dialkyl arenesulfinylmethanephosphonates

The synthesis of racemic oc,P-unsaturated sulfoxides by the Homer-Wittig olefination of aldehydes is a well-established process [15]. In this procedure, deprotonation of a dialkyl arenesulfinylmethanephosphonate and reaction of the resulting anionic species with an aldehyde gives oc,P-unsaturated sulfoxides in high yield, but with variable (E) (Z) ratios according to the nature of the aldehyde. For example, reaction of a-phosphoryl sulfoxide (7) with benzaldehyde (8) gives the ct,P-unsaturated sulfoxide (9) in 70% yield with an ( ) (Z) ratio of 58 42 (Scheme 5.3) [16]. 

Dialkyl arenesulfinylmethanephosphonates are available by S-oxidation of the corresponding dialkyl arenesulfenylmethanephosphonates or by reaction of anions derived from dialkyl methanephosphonates with sulfinate esters. With regard to the synthesis of optically active a,P-unsaturated sulfoxides, the former method may not be applied in the absence of a reliable, highly enantioselective 5-oxidation procedure without recourse to resolution methods, while the latter method suffers from the relatively polar nature of dialkyl arenesulfinylmethanephosphonates, which renders their chromatographic separation tedious and costly. 

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See also in sourсe #XX -- [ , ]

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