A novel conversion of dibenzazecines into homoerythrina compounds: Synthesis of cis-16,17-dimethoxyhomoerythrinan-3-one.
作者:HITOSHI TANAKA、YASUSHI TAKAMURA、MASAYOSHI SHIBATA、KAZUO ITO
DOI:10.1248/cpb.34.24
日期:——
Two dibenzazecine derivatives (8 and 9) were readily prepared as a mixture by a photochemical reaction of the bromophenolic compound (6). Reduction of the mixture (8 and 9) with diborane followed by column chromatography on silica gel gave the secondary amine (11), which was converted into the diene derivative (12) by Birch reduction. Treatment of 12 with 5% hydrochloric acid, followed by O-methylation with diazomethane provided the homoerythrina base (1) in 21% yield.On the other hand, the base (1) was also prepared via Birch reduction of the amine (9). The mixture of the amides (8 and 9) was reduced directly with sodium in liquid ammonia and subjected to fractional crystallization to yield 13. On treatment with 5% hydrochloric acid, 13 produced the homoerythrina derivative (14), which was methylated with diazomethane to afford 15. Finally, the homoerythrina base (1) was obtained by reduction of the amide group in 15.
通过对溴酚类化合物 (6) 的光化学反应,很容易制备出两种二苯并吖嗪衍生物(8 和 9)的混合物。用二硼烷还原混合物(8 和 9),然后在硅胶上进行柱层析,得到仲胺(11),再通过桦木还原法将其转化为二烯衍生物(12)。用 5%的盐酸处理 12,然后用重氮甲烷进行 O-甲基化,可得到均赤藓酮碱(1),收率为 21%。酰胺(8 和 9)的混合物直接用钠在液氨中还原,然后进行分馏结晶,得到 13。用 5%的盐酸处理后,13 生成了均赤藓红衍生物(14),用重氮甲烷对其进行甲基化,得到了 15。最后,通过还原 15 中的酰胺基,得到均红藤碱 (1)。