Regioselective Bromination of Benzocycloheptadienones for the Synthesis of Substituted 3,4-Benzotropolones Including Goupiolone A
作者:Deniz Arican、Stefan Braukmüller、Reinhard Brückner
DOI:10.1002/chem.201700622
日期:2017.4.3
hitherto unknown 3,4‐benzotropolones. The 8‐ethoxycarbonylated dimethyl‐3,4‐benzotropolone 50 obtained by this route was dimethylated to give goupiolone A (52). This synthesis encompasses 9 steps from 22, that is, half as many as the only previous synthesis (19 steps). A variant of our route afforded the 1,8‐dibromide 54. Coupling with excess phenylboronic acid and ketal hydrolysis provided the diphenylated
型- 18个或- 23 benzocycloheptadienones通过闭环复分解烯烃容易地制备。添加溴2至23和消除溴化氢给溴代烯烃28使用DBU或其异构体异28使用DABCO,都与近乎完美的区域控制。两个28和异- 28后行的Sonogashira,铃木,根岸,并赫克以及Pd催化alkoxycarbonylations耦合。水解所得的α-酮基酮和释放的α-二酮烯醇化提供了迄今未知的3,4-苯并呋喃酮类产品。8-乙氧基羰基化的二甲基-3,4-苯并恶臭酮50将通过该途径获得的产物二甲基化以得到古匹酮A(52)。该合成包含22个步骤中的9个步骤,即,仅以前的合成步骤(19个步骤)的一半。我们路线的一种变体提供了1,8-二溴化物54。与过量的苯基硼酸和缩酮水解的偶联提供了二苯基化的苯并二氮杂戊酮56,并提出了一种策略,通过该策略可以达到天然的双spulvinone aurantricholone(7)。