Diethyl dithioacetal partial demercaptalation

Benzyl 1-thio-lactoside and ethyl lactoside, prepared from lactose dibenzyl dithioacetal116 by the preceding methods, are necessarily pyranosides (owing to the substitution on 0-4). Stevens and coworkers310 prepared ethyl 2,3 4,5-di-0-isopropylidene-l-thio-/3-D-glucoseptanoside by partial demercaptalation of 2,3 4,5-di-O-isopropylidene-D-glucose diethyl dithioacetal. 

Ethyl 2-amino-2-deoxy-l-thio-a- and -jS-o-arabinopyranoside have been obtained by direct ethanethiolation of 2-amino-2-deoxy-D-arabinose, whereas ethyl 2-amino-2-deoxy-l-thio-a- and -jS-D-arabinofuranoside were prepared by partial demercaptalation of a 2-amino-2-deoxy-D-arabinose diethyl dithioacetal derivative with either mercuric chloride or bromine (see Scheme 10). Demer-... 

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