7,7-Dimethyltricyclo(3.3.0.02,8)octan-3-ones as Synthetic Intermediates. VI. An Improved Formal Synthesis of (.+-.)-Descarboxyquadrone via Highly Regioselective Cyclopropane Ring Opening of Tricyclo(3.3.0.02,8)octan-3-one.
作者:Takeshi IMANISHI、Masayuki YAMASHITA、Munetaka MATSUI、Tetsuaki TANAKA、Kazuyuki MIYASHITA、Chuzo IWATA
DOI:10.1248/cpb.40.2691
日期:——
The cyclopropane ring opening reaction of 7, 7-dimethyl-3-oxotricyclo[3.3.0.02, 8]octane-5-acetic acid (5) was examined. A regioselective C(1)-C(2) bond cleavege of 5 proceeded smoothly under acidic conditions to give a bicyclo-[3.2.1]octan-3-one derivative 7 in good yield, as a result of neighboring-group participation of the carboxyl group. The lactone 7 was then successfully transformed into the 1, 4-diketone 9, a useful intermediate for total synthesis of (±)-descarboxyquadrone (4).
7, 7-二甲基-3-氧三环[3.3.0.02, 8]八烷-5-乙酸(5)的环丙烷环开环反应进行了研究。在酸性条件下,5的C(1)-C(2)键选择性断裂顺利进行,产生了邻位参与的羧基衍生物双环-[3.2.1]八酮7,且产率良好。然后,乳酸酯7成功转化为1, 4-二酮9,这是一种用于(±)-脱羧四铵(4)全合成的有用中间体。