Desulfurization mercuric chloride

Dimethyl ketals and enol ethers are stable to the conditions of oxime formation (hydroxylamine acetate or hydroxylamine hydrochloride-pyridine). Thioketals and hemithioketals are cleaved to the parent ketones by cadmium carbonate and mercuric chloride. Desulfurization of thioketals with Raney nickel leads to the corresponding methylene compounds, while thioenol ethers give the corresponding olefin. In contrast, desulfurization of hemithioketals regenerates the parent ketone. ... 

The more generally known mercuric oxide-mercuric chloride hydrolysis 2 may also be used, and in the present case it gives a yield of about 90%. The reductive desulfurization of Part E is also based on the work of Mukaiyama.12 It is clearly superior to Raney nickel desulfurization, which gives only 36-45% of 3-benzylindole. 

Ethyl 2-acetamido-2-deoxy-l-thio-a-D-glucofuranoside (103) was oxidized with lead tetraacetate to the partially protected dialdose (104), which, with nitromethane, gave a mixture of the 5-epimeric 6-nitro thioglycosides (105). The 2-acetamido-2,6-dideoxy-6-nitro-hexoses (106) produced therefrom by desulfurization with mercuric chloride were not separated, but were cyclized immediately, in the presence of barium hydroxide, to a mixture of l-acetamido-l,3-di-deoxy-3-nitroinositol salts (107). Acidification, hydrogenation, and acetylation then afforded 108 (and a stereoisomer). 

The hydrolysis of glycose diethyl dithioacetals and 1-thioglycosides in the presence of mercuric chloride represents a special case where the high afl nity of mercury for the sulfur function profoundly influences the reaction. The procedure has been used as an alternative to acid hydrolysis for conversion of a 1-thiofuranoside into the free sugar without cleavage of an acid-labile group, as in the one-step conversion of ethyl 2-acetamido-2-deoxy-l-thio-o-D-xylofuranoside into 2-acetamido-2-deoxy-D-xylose. Attempted replacement of the ethylthio group by methoxyl in ethyl 1-thio-/3-D-mannopyranoside, with mercuric chloride and cadmium carbonate in methanol, was unsuccessful. Mercuric chloride normally effects desulfurization of acyclic dithioacetals. ... 

This procedure for the preparation of l-ethyl-3-(3-dimethyl-amino)propylcarbodiimide and its salts is a modification of one that has been published.4 Unsymmetrical carbodiimides have also been prepared by desulfurization of the corresponding thioureas with mercuric oxide3 or by dehydration of the corresponding ureas with -toluenesulfonyl chloride in pyridine.4 Unsymmetrical 1,3-disubstituted ureas are best prepared by the reaction... 

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