Search for carbon-carbon bond formation by the use of boranonitrone

硼硝酮，由保护肟与BF_3合成。OE_t2与烯烃进行分子间环加成，得到相应的异恶唑烷，收率高。有趣的是，n -硼烷-c -乙氧羰基硝基酮与烯烃的环加成反应得到3,5-反式异恶唑烷，而丁基二甲基硅氧烷- n， n -二甲基乙烷酰胺与烯烃的反应得到3,5-顺式异恶唑烷。该反应可用于通过还原裂解N-O键合成1,3-抗和1,3-顺氨基醇。此外，n -硼烷- c -乙氧羰基硝基与碳自由基反应可产得相应的羟胺。

Boranonitrone, generated from protected oxime with BF_3.OE_t2, underwent intermolecular cycloaddition with alkenes to afford the corresponding isoxazolidines in good yields. Interestingly, the cycloaddition of N-borano-C-ethoxycarbonyl nitrone with alkenes gave 3,5-trans-isoxazolidines, whereas the reaction of tent-butyldimethylsilyloximino-N,N-dimethylethane-amide with alkenes afforded 3,5-cis-isoxazolidines. This reaction is very useful for synthesis of 1,3-anti and 1,3-syn aminoalcohols by reductive cleavage of an N-O bond. Additionally, the reaction of N-borano-C-ethoxycarbonyl nitrone with carbon radical species afforded the corresponding hydroxylamines in good yields.