Synthesis of "dihydroacarbose", an alpha-D-glucosidase inhibitor having a pseudo-tetrasaccharide structure

"Dihydroacarbose" (2), an alpha-D-glucosidase inhibitor having a pseudo-tetrasaccharide structure, was synthesized by reductive coupling of 4(3)-amino-1(1),6(1)-anhydro-2(1),3(1),2(2),3(2),6(2),2(3),3(3)-hepta-O- benzyl-4(3),6(3)-dideoxy-beta-maltotriose and 2D-(2,4/3,5)-2,3,4-tris(benzyloxy)-5-(trityloxymethyl)cyclohexa non e with sodium-cyanoborohydride. The former intermediate was prepared from a partially benzylated 1(1),6(1)-anhydro-beta-maltotriose, and the latter was prepared from a chiral, penta-substituted cyclohexene derived from D-glucose. The synthetic 2 was found to be a strong, non-competitive inhibitor (Ki = 1.13 x 10(-6) M) against small-intestinal sucrase of rat.