Amylostatin , 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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