This paper reports the polycondensation of benzyl 2-amino-2-deoxy-a-o-glucopyranoside hydrochloride (1) with carbon dioxide using the triphenylphosphine/carbon tetrachlorideDBU system as a condensing agent to give poly(urethane) (2). The polycondensation of 1 with COz was carried out in DMF solvent in the presence of the condensing agent under CO, atmosphere. From the NMR and IR analyses of the product, the polymerization proceeded regioselectively to form 2. The molecular weight was estimated as 2000-3000 by GPC measurement after acetylation of 2, corresponding to DP = 5-8.ActaPolymer., 48, 310-313 (1997) Regioselective polycondensation of benzy12-amino-2-deoxy-a-o-glucopyranoside .. .Regioselective polycondensation of benzyl2-amino-2-deoxy-a-o-glucopyranoside . . .

Feeding studies with Taxus suspension cells employing labeled 5α-hydroxytaxadiene and 5α,10β-dihydroxytaxadiene, and the corresponding 5α-acetate esters, demonstrated that acetylation at C5 of the monool precursor promotes the formation of 14β-hydroxy taxoids, such as taxuyunnanine C, at the expense of 13α-hydroxy taxoids, including Taxol and its congeners, but that the major bifurcation in taxoid biosynthesis, toward 13α-or 14β-hydroxy taxoids, occurs after 10β-hydroxylation of the taxane core.

The putative taxol biosynthesis metabolites, taxa-4(20),11(12)-diene-5α, 13α -diol (7), taxa-4(20), 11(12)-diene-5α, 9α, 13α-triol (9), and taxa-4(20),11(12)-diene-5α, 10β, 13α-triol (10), have been prepared by Barton deoxygenation of the C-9 and C10-hydroxyl groups of protected derivatives of taxusin, a major taxoid metabolite isolated from Yew heart wood. The synthetic protocol devised, is amenable for the preparation of isotopically labeled congeners that will be useful to probe further intermediate steps in the biosynthesis of taxol.

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