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[摘要]：(C5'-R) diastereoisomers of uracil polyoxin C Me ester have been developed. The key stereocontrolled step involves nucleophilic addn. of trimethylsilyl cyanide to the appropriate chiral sulfinimine derived from 2',3'-protected 5'-formyluridine and (S)-(-)-tert-butanesulfinamide or (R)-(+)-tert-butanesulfinamide, resp. A variety of substrate mimics designed to function as inhibitors of chitin synthase have been with activated isoxazole carboxylic acids. Amide bond formation was accomplished via coupling of the amino functionality of UPOC Me ester with a free isoxazole acid using HBTU or alternatively an isoxazole pentafluorophenyl ester. The substrate mimics incorporate features of the nucleoside-peptide antibiotics, the polyoxins and the nikkomycins, as well as features of the transition state structure expected during polymn. of the natural chitin synthase substrate uridine diphosphoryl-N-acetylglucosamine (UDP-GlcNAc), namely, a metal-binding site and glycosyl oxocarbenium ion mimic. |
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