Quinolizidines. XIV. A racemic synthesis of 9-demethyltubulosine, an alkaloid isolated from Alangium vitiense.
作者:MASASHI OHBA、MITSUKO HAYASHI、TOZO FUJII
DOI:10.1248/cpb.33.3724
日期:——
The first total synthesis of the Alangium vitiense alkaloid 9-demethyltubulosine (1) has been achieved in the form of a racemic modification through a"lactim ether route, " which included the intermediates (±)-7, (±)-8, (±)-10, and (±)-9. The 1'α-Hisomers (±)-12 and (±)-11 were also produced through this synthetic route. On the other hand, the nonconformity of synthetic (±)-1 with another (-)-demethyltubulosine from A. lamarckii indicated the alternative 10-demethyl structure (2) to be correct for the A. lamarckii alkaloid. The assignments of the configuration at C-1' of (±)-1, (±)-9, (±)-11, and (±)-12 were based on four criteria, namely, the ratio of products from the catalytic reduction of (±)-10, thin-layer chromatographic mobility, and 1H and 13C nuclear magnetic resonance spectral features.
通过 "内脂醚路线",首次以外消旋的形式合成了Alangium vitiense生物碱9-去甲基胞嘧啶(1),其中包括中间体(±)-7、(±)-8、(±)-10和(±)-9。通过这条合成路线还生产出了 1'α 异构体 (±)-12 和 (±)-11。另一方面,合成的(±)-1 与来自 A. lamarckii 的另一种 (-)-demethyltubulosine 不一致,这表明替代的 10-去甲基结构 (2) 对于 A. lamarckii 生物碱来说是正确的。(±)-1、(±)-9、(±)-11 和 (±)-12 的 C-1'构型的确定基于四个标准,即 (±)-10 催化还原产物的比例、薄层色谱流动性以及 1H 和 13C 核磁共振光谱特征。