Synthesis of Polyhydroxylated 2H-Azirines and 2-Halo-2H-azirines from 3-Azido-2,3-dideoxyhexopyranoses by Alkoxyl Radical Fragmentation

Abstract

The reaction of 3-azido-2,3-dideoxypyranose and 3-azido-2,3-dideoxy-2-halohexopyranose compounds with (diacetoxyiodo)benzene and iodine generated 2-azido-1,2-dideoxy-1-iodoalditols and 2-azido-1,2-dideoxy-1-halo-1-iodoalditols, respectively. These beta-iodo azides could be transformed by chemoselective dehydroiodination into 2-azido-1,2-dideoxy-4- O-formyl-pent-1-enitols and (Z, E)-2-azido-1,2-dideoxy-1-halo-4- O-formyl-pent-1-enitols in good yields. Thermolysis and photochemical studies of these vinyl azides and 1-halovinyl azides for the synthesis of polyhydroxylated 3-alkyl-2 H-azirines and the hitherto unknown 2-halo-3-alkyl-2 H-azirines have also been accomplished.

Radicals and Carbohydrates

“…Starting from 3-azido-2,3dideoxy-hexopyranose compounds 244, we had the opportunity to synthesize chiral β-iodoazides 245 in good yields, which by subsequent base treatment afforded vinyl azides 246. 297 Analogously, the corresponding vinyl sulfones could be prepared from the oxidative fragmentation of 2,3-dideoxy-3phenylsulfonyl-hexopyranoses. 298 We also reported on an extension of the ARF methodology to 2-azido-2-deoxyaldoses to lead to aldononitriles such as 247 by oxidation to the α-azido cation which delivers nitriles upon loss of nitrogen.…”

Synthesis of New 2-Halo-2-(1H-tetrazol-5-yl)-2H-azirines via a Non-Classical Wittig Reaction

“…This study allowed the synthesis of a range of 2-halo-2 H -azirines with several substituents, including the first examples of 2-bromo and 2-iodo-2 H -azirine derivatives. Since then, a few examples of halo substituted azirines prepared from haloazidoalkenes by thermal or photochemical decomposition have been reported [11,12,13,14].…”

Metal‐Free Regioselective Chloroazidation of Internal Alkynes

“…[16] Neighboring group participation by the benzoate might facilitate the reaction and the observed regioselectivity. There are hardly any literature reports for the preparation of chloro-2H-azirines [16,17] and our method is an easy two-step procedure starting from readily available alkynes. To the best of our knowledge,t his is the first example of ac hloro-2H-azirine bearinganeighboring CH 2 OR group.…”