The synthesis of various cycloalkana[d ]xanthones and conversion of the cyclohexa-analogue to a 7,7a-dimethylcyclohexa[d ]xanthene †
作者:Roy M. Letcher、Tai-Yuen Yue、Kwei-Fung Chiu、Avijit S. Kelkar、Kung-Kai Cheung
DOI:10.1039/a804365e
日期:——
The synthesis of cyclo-penta-, -hexa- and -hepta-[d]xanthones 5 from (E)-(2-hydroxyphenyl)-5-arylpent-4-ene-1,3-diones 4, cycloalkanones and pyrrolidine is described. Reactions to modify 5 in an attempt to synthesize analogues of the five naturally occurring cyclohexa[d]xanthenes (with general formula 1) are also described: these reactions include C-methylations at C-7 and C-7a, hydride reduction of the 8-keto group, dehydroxylations and finally catalytic reduction to give 16. The stereochemistry of 16 established by NOE and an X-ray crystal structure of 9aB differs from 1 at two contiguous C-atoms.
本文描述了从(E)-(2-羟基苯基)-5-芳基戊-4-烯-1,3-二酮 4、环烷酮和吡咯烷合成环五、六和七-[d]氧杂蒽酮 5 的过程。此外,还描述了对 5 进行改性以试图合成五种天然环己基[d]氧杂蒽类似物(通式 1)的反应:这些反应包括 C-7 和 C-7a 的 C-甲基化、8-酮基的氢化物还原、脱羟基,最后通过催化还原得到 16。通过 NOE 和 9aB 的 X 射线晶体结构确定的 16 的立体化学结构在两个连续的 C 原子上与 1 不同。