Multigram scale synthesis of formyl tetra-O-benzyl-β-d-C-glucopyranoside using benzothiazole as a formyl group equivalent

The addition of 2-lithiobenzothiazole to d-gluconolactone followed by deoxygenation of the resulting ketose affords a mixture of benzothiazolyl α- and β-d-glucopyranoside; treatment of this mixture with sodium methoxide gives the β-anomer from which the title aldehyde is obtained in a pure form by transformation of the benzothiazole ring into the formyl group.