PREPARATION OF AMYLOSE DERIVATIVES SELECTIVELY MODIFIED AT C-6 - 6-AMINO-6-DEOXYAMYLOSE

The synthesis of various amylose derivatives selectively modified at C-6 leading to the preparation of 6-amino-6-deoxyamylose (4) was carried out under homogeneous conditions. Amylose was initially halogenated directly at the primary carbon either by using methanesulfonyl chloride in dimethylformamide/lithium chloride as solvent, giving 6-chloro-6-deoxyamylose (1) or with triphenylphosphine and N-bromosuccinimide in dimethylformamide/lithium bromide, giving 6-bromo-6-deoxyamylose (2). Several of these derivatives with different degrees of substitution were prepared. C-6 chlorinated amyloses were then converted to the corresponding 6-azido-6-deoxyamylose analogs (3) by chloride displacement with azide ion in dipolar aprotic media. Triphenylphosphine facilitated reduction of these intermediates in dimethyl sulfoxide gave 6-amino-6-deoxyamyloses with the same degrees of substitution as the C-6 chlorinated precursors. Products were characterized in terms of the site and the extent of modifications using C-13 NMR, FTIR, HPLC, and elemental analyses.