Syntheses of derivatives of <i>N</i>-acetyl-<scp>D</scp>-lactosamine from <scp>D</scp>-lactal hexaacetate. Hexa-<i>O</i>-acetyl-2-deoxy-2-phthalimido-β-<scp>D</scp>-lactosyl chloride

Abstract

Two reaction routes are presented for the preparation of hexa-O-acetyl-2-deoxy-2-phthalimido-β-D-lactosyl chloride (7) from lactal hexaacetate (1). One route involves, in the first stage, reaction of 1 with nitrosyl chloride and proceeds by way of benzyl 2-amino-2-deoxy-α-D-lactoside (4) as an intermediate. The other route, which is considered more efficient, involves reaction of 1 with cerie ammonium nitrate and sodium azide and involves the β-anomer (12) of 4 as an intermediate. The preparation of 7 is of interest as a reagent for the preparation of 2-amino-2-deoxy-β-D-lactosides. The procedures offer routes for the preparation of D-lactosamine.