5-EXO-DIG RADICAL CYCLIZATION OF 1,2,6-TRIDEOXY-6-IODO-L-ARABINO-HEX-1-YNITOLS DERIVATIVES

Free radical cyclisation of the title iodides led to five-membered car bocycles in good yield. With enzyl-1,2,6-trideoxy-6-iodo-L-arabino-hex -1-ynitol (9a), a three step process (5-exo-dig-cyclisation, [1,5] hyd rogen atom transfer, fragmentation) resulted in extrusion of benzaldeh yde giving mainly a mixture of (IS, 2R)-2-benzyloxy-4-methylene cyclop entan-1-ol (11a) and (1S, 2R)-2-benzyloxy-4-methylcyclopent-3-en-1-ol (12a). With eoxy-3,4-di-0-methyl-6-iodo-L-arabino-hex-1-ynitol (9b) or 1,2,6-trideoxy-6-iodo-L-arabino-hex-1-ynitol (9c), the expected (1S, 2S, 3S)-2,3-dimethoxy-4-methylene cyclopentan-1-ol (10b) or (1S, 2S, 3 S)-4-methylenecyclopentan-1,2,3-triol (10c), were respectively obtaine d.