Picolinyl group as an efficient alcohol protecting group: cleavage with Zn(OAc)2·2H2O under a neutral condition

As an efficient alcohol protecting group, picolinates (Pic), prepared from the corresponding alcohols using commercial picolinoyl chloride, are readily cleaved by Zn(OAc)2 or Cu(OAc)2, even in the presence of other common alcohol protecting groups. Moreover, the picolinyl group at C-2 position in carbohydrates can be selectively cleaved to give methyl 4,6-O-benzylidene-3-O-picolinyl-α-d-glucopyranoside and 3-O-picolinyl methyl-4,6-O-benzylidene-α-d-galactopyranoside in good yields.