Amylostatins synthesis

The first synthesis, by method a, of amylostatin (XG) was reported by Kuzuhara and Sakairi. The synthon for the cyclohexene moiety was the benzylated allyl bromide 382, derived from D-glucose by the sequence 378 — 382 of the Perrier reaction. The coupling reaction of 382 using an excess of 4-amino-T,6 -anhydro-4,6-dideoxymaltose tetrabenzyl ether (383), and sodium iodide in DMF for 3 days produced a mixture of the epimeric monocarba-trisaccharide derivatives, separation of which gave the protected derivatives in 15% yield. 

An alternative synthesis,by method h, was conducted by coupling 357 and 1,6-anhydro-4-0-(3,4-anhydro-6-deoxy-a-D-galactopyranosyl)-a-D-glucopyranose (392a) in 2-propanol at 120° this yielded a diastereoiso-meric mixture, from which, after the usual treatment, amylostatin (XG) was isolated in 20% yield. 

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