| 摘要 |
<p>Prepn. of 1-ethyl-1-formyl-1,2,3,4,5,6,7,12b-octahydroindolo 2,3-alpha - quinolizine (I) comprises reacting 3,4-dihydro-9H-pyridio 3,4-b indole with a pentene of formula (IV) (where X is Br or I; R is a gp. with a pentene of formula (IV) (where X is Br or I1 R is a gp. eliminable under conditions of a Mannich reaction, esp. -B(alkyl)2, gamma, -Al(alkyl)2, R' -Sn(alkyl)3 or a gp. SiR1R2; each of R' and R2 and R3 is 1-4C alkyl, 1-4C alkyl)amino or Cl). 2-Ethyl-5-bromo-1-trimethylsilyloxy-1- pentene is specifically claimed. (I), an intermediate for prepn. of vincamine, is prepd. in higher yield than when made by using cpds. of formula (III) instead of (IV). Lewis acid catalysts are not needed. Typically, 3,4-dihydro-9H-pyridio 3,4-b indole and 2-ethyl-5-bromo-1-trimethylsilyloxy-1-pentene in dimethylformamide are heated at 60 degrees C for 16 h. under argon, evapd. and purified with silica gel to give equal quantities of the (1RS, 12BSR)-and (1RS, 12bRS)-stereoisomers.</p> |
