| 主权项 |
1. A process for preparing a compound of formula (IV): comprising:
(a) selectively hydrolyzing a compound of formula (VII), wherein each R2 is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (C1-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-t-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, t-butylmethoxyphenylsilyl, t-butoxydiphenylsilyl), allyloxycarbonyl (alloc, —C(O)O—CH2CH═CH2), and t-butoxylmethyl; to provide a compound of formula (II), wherein each R2 is defined as hereinabove;(b) reacting the compound of formula (II) with a compound of formula (I), wherein each R1 is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (C1-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-t-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, t-butylmethoxyphenylsilyl, t-butoxydiphenylsilyl), allyloxycarbonyl (alloc, —C(O)O—CH2CH═CH2), and t-butoxylmethyl; X is halogen, OH, alkylthio, arylthio, sulfoxide (R′S(═O)—), sulfone (R′S(═O)2—), sulfonate (e.g., mesylate, tosylate, or triflate), OC(═NH)CCl3, OPO3H, OPO3R′ or OCH2CH2CH2CH═CH2, wherein R′ is (C1-C4)alkyl or aryl, and the anomeric carbon attached with X can be either α or β configuration; to provide a compound of formula (III), wherein R1 and R2 are defined as hereinabove;
(c) removing the protecting groups R1 and R2 of the compound of formula (III) to provide the compound of formula (IV). |
