Diethyl dithioacetal irradiation

Extended irradiation of the diethyl dithioacetal 44 increases the yield of L-fucitol (46) at the expense of 1-S-ethyl-l-thio-D-galactitol (45) also galactitol (52) was isolated from the photolysis mixture.109 The intermediacy of 45 in the formation of 46, a possibility that was suggested by the extended photolysis of 44, is supported by the observation that irradiation of 45 in methanol produces L-fucitol (46) in 44% yield.109 (Compounds 47 and 52 also are formed during irradiation of 45, but in low yield.) The mechanism for sulfide photoreaction parallels that109 for the alkyl dithioacetals (see Scheme 18). 

The irradiation of alkenyl acetals derived from monosaccharides has provided a new route to inositol derivatives, as illustrated in Scheme 2 the diethyl acetal (20) yielded the epimeric ethyl ether derivatives (21), whilst the corresponding dithioacetal (22) gave the inosose dithioacetal (23). The 2,5-di-deoxystreptamine derivative (24) suitably protected for use as an intermediate... 

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