Research On N-O Bond Cleaving Rearrangements Based On The Strategy Of Self-hydride Transferring Strategy

Our group has been commited a long term to study new organic reactions based on self-hydride transferring and has uncovered that cis-N-methylisoxazolidine could be converted to cis-1,3-oxazinane cis-specificly under the catalysis of [RuCl3(p-cymene)]2 via self-hydride transferring N-O bond cleavage and rearrangement, this strategy was applied to study other new reaction. This thesis consists of the following sections:(1) It was found that increase the amount of catalyst up to 5 mol% was efficient enough to convert the chiral cis-N-methylisoxazolidine to chiral cis-1,3-oxazinane, which was then applied to the asymmetric total synthesis of ceramide ihibitor (-)-HPA-12 within 3 steps with high diastereoselectivity.(2) Iridium was found efficient to catalyze the N-O bond cleavage and rearrangement of 2,3-dihydroisoxazole, poly-substitued pyrrolidine could be easily obtained after the intermediate was captured by electron deficient alkene, Subsequently, poly substituted pyrrole could be easily oabtained after oxidation-aromatization by DDQ in one pot.(3) 2,3-dihydroisoxazole was usually obtained in several steps from easily available nitrone and non-electron-defficient terminal alkyne in above research. It was found that ZnI2/Et3N could promote the [3+2] cycloaddition of nitrone and non-electron-defficient terminal alkyne generating 2,3-dihydroisoxazole with generally high yield. At lower temperature, ZnI2/(iPr)2NEt was found efficiently eough to promote the [3+ 2] cycloaddition of chiral nitrone and non-electron-defficient with high diastereoselectivity.