Cyclization in situ of enose-/ynose-nitrilimines: an expedient approach to the synthesis of chiral glycopyrazoles and pyrazolonucleosides
摘要:
Intramolecular [3 + 2] nitrilimine cycloaddition reactions on carbohydrate-derived substrates proceed in a regioselective fashion, affording structurally novel chiral glycopyrazoles (4-6 and 10a-c) in good yields. The products can be subsequently transformed to bicyclic pyrazoles (viz. 11 from 4) or nucleoside analogues (viz. 12 from 4). (C) 2004 Elsevier Ltd. All rights reserved.
Cyclization in situ of enose-/ynose-nitrilimines: an expedient approach to the synthesis of chiral glycopyrazoles and pyrazolonucleosides
摘要:
Intramolecular [3 + 2] nitrilimine cycloaddition reactions on carbohydrate-derived substrates proceed in a regioselective fashion, affording structurally novel chiral glycopyrazoles (4-6 and 10a-c) in good yields. The products can be subsequently transformed to bicyclic pyrazoles (viz. 11 from 4) or nucleoside analogues (viz. 12 from 4). (C) 2004 Elsevier Ltd. All rights reserved.