Spiro sugar-isoxazolidine scaffold as useful polyfunctional building block for peptidomimetics design
摘要:
Spiro sugar-isoxazolidines obtained by 1,3-dipolar cycloaddition of activated exo-glycals and nitrones were efficiently functionalized at two sites, i.e. C-4 and C-7, with arginine, arginine mimetics and guanidylated appendages. Two bicyclic sugar derivatives differing by the configuration at C-7 were chosen as model compounds. The small library of peptidomimetics was evaluated toward inhibition of VEGF-A165/neuropilin-1 binding. Unexpected cleavage of C3-C4 bond of isoxazolidine moiety was observed during hydrogenolysis and opened thus a new way toward hemiketal structures which could also find interesting applications as less constrained scaffold. (C) 2016 Elsevier Ltd. All rights reserved.
Cycloaddition reactions of activated exo-glycals and nitrones proceeded only under microwave activation, with excellent facial selectivities on furanoglycosylidenes and good stereocontrol on the nitrone producing only two diastereomeric spiroisoxazolidines. alpha/beta-Spiro sugar-isoxazolidines are obtained from pyrano exo-glycals. The cycloaddition reaction with nitrile oxide proceeds at room temperature and gives open-chain isoxazoles due to facile beta-elimination of the sugar ring oxygen on the intermediate isoxazoline ring system. All the heterocycles obtained this way can be regarded as nucleoside analogues. (C) 2005 Elsevier Ltd. All rights reserved.
Spiro sugar-isoxazolidine scaffold as useful polyfunctional building block for peptidomimetics design
Spiro sugar-isoxazolidines obtained by 1,3-dipolar cycloaddition of activated exo-glycals and nitrones were efficiently functionalized at two sites, i.e. C-4 and C-7, with arginine, arginine mimetics and guanidylated appendages. Two bicyclic sugar derivatives differing by the configuration at C-7 were chosen as model compounds. The small library of peptidomimetics was evaluated toward inhibition of VEGF-A165/neuropilin-1 binding. Unexpected cleavage of C3-C4 bond of isoxazolidine moiety was observed during hydrogenolysis and opened thus a new way toward hemiketal structures which could also find interesting applications as less constrained scaffold. (C) 2016 Elsevier Ltd. All rights reserved.