通过可见光光氧化还原催化的催化脱氢(CD)为芳香族化合物的合成提供了一条有效的途径。然而,由于在光催化条件下难以控制胺的反应性,通过可见光诱导的环糊精来获得广泛使用的合成部分的N-芳基胺仍然是一个重大挑战。在这里,可见光诱导光催化合成N-芳基胺是通过烯丙胺的CD实现的。使用C 6 F 5 I作为氢原子受体的不寻常策略使得带有各种官能团和活化C-H键的胺能够温和且受控的CD,从而抑制反应性N-芳基胺产物的副反应。彻底的机理研究表明,单电子和氢原子转移以明确的顺序参与,以在控制反应性方面提供协同效应。值得注意的是,反电子转移过程可防止所需产物在氧化条件下进一步反应。
Chiral synthesis via organoboranes. 28. Reaction of .alpha.-chiral organyldichloroboranes with organyl azides providing a synthesis of secondary amines with exceptionally high enantiomeric purities
作者:Herbert C. Brown、Ashok M. Salunkhe、Bakthan Singaram
DOI:10.1021/jo00003a046
日期:1991.2
2-Alkyl-1,3,2-dioxaborinanes R*BO2(CH2)3 of essentially 100% enantiomeric purity were prepared by the asymmetric hydroboration of readily available prochiral olefins with mono- or diisopinocampheylboranes, followed by removal of the chiral auxiliary (alpha-pinene). The intermediate R*BO2(CH2)3 reacts readily with lithium aluminum hydride at 0-degrees-C to give the corresponding lithium monoalkylborohydrides stereospecifically in very good yields and in very high enantiomeric purities. The lithium monoalkylborohydrides, on treatment with hydrogen chloride in dimethyl sulfide, give the corresponding monoalkyldichloroboranes in very high enantiomeric purity. The intermediate monoalkyldichloroboranes react readily with organic azides in 1,2-dichloroethane with evolution of gaseous nitrogen and transfer of the organic group from boron to nitrogen with complete retention of configuration to provide the corresponding secondary amines, either (+)- or (-), in very high yields and exceptionally high enantiomeric purities. The procedure was applied to the synthesis of representative optically active amines of high enantiomeric purities (ee or de greater-than-or-equal-to 99%), including (2S,2'S)-di-2-butylamine, N-[(2S)-2-methyl-1-butyl]-(1S,2R)-trans-2-phenycyclopentylamine, N-[(3S)-3,7-dimethyloct-6-enyl](1S,2S)-trans-2-methylcyclohexylamine, and the meso-di-2-butylamine.
BROWN, HERBERT C.;SALUNKHE, ASHOK M.;SINGARAM, BAKTHAN, J. ORG. CHEM., 56,(1991) N, C. 1170-1175
作者:BROWN, HERBERT C.、SALUNKHE, ASHOK M.、SINGARAM, BAKTHAN