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A five-step preparation of carbohydrate-based oxepines from hept-l-enitols is presented. The hept-l-enitols were subjected to silyl protection and hydroboration/oxidation to give the protected heptan-1-itols. Swern oxidation of the homologated alcohols followed by sequential acetal formation/ cyclization provided methyl 2-deoxyseptanosides that underwent elimination reactions to give the carbohydratebased oxepines. The new sequence is an alternative to the ring-closing metathesis for the synthesis of carbohydratebased oxepines from protected pyranose sugars. The product oxepines can serve as glycosyl donors in the synthesis of novel septanose carbohydrates. In addition, C-methylenealdehydo arabinofuranoside 16 was formed from 2-deoxyseptanoside 10 as the only product during protic acid mediated elimination reactions. This novel ring contraction complements other reported preparations of C-methylenaldehydo furanosides and underscores the acid-mediated reactivity introduced by competing eliminations between the C-1/C-2 and C-2/C-3 bonds. [ABSTRACT FROM AUTHOR]

The radical reaction of tributyltin hydride with o-iodo-N- methylanilides derived from α-azido acids provides an excellent access to α-(aminocarbonyl)iminyl radicals through 1,5-hydrogen transfer reaction of initially formed aryl radicals followed by β-elimination of dinitrogen from ensuing α-azido-α-(aminocarbonyl)alkyl radicals. The outcoming iminyls display a peculiar tendency to form corresponding nitriles by β-elimination of aminocarbonyl radicals. [ABSTRACT FROM AUTHOR]