Tuneable regioselectivity during the mono-etherification of the 2,3-diol of a mannose derivative

• Regioselectivity for either the 3- or the 2-hydroxyl group of a manno-pyranoside.
• Catalyst concentration dependence of selectivity.
• Different diaryldiazomethanes give different regioselectivity.

The paper reports selective mono-etherification of the 2-, and 3-hydroxyl groups of methyl 4,6-O-isopropylidene-α-d-mannopyranoside using tin(II) chloride catalysed reactions of diaryldiazomethanes. By the use of different diazo compounds and the variation of the tin(II) chloride concentration the ether formation can be shifted from over 90% 3-selectivity to over 90% 2-selectivity.

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