A regioselective synthesis of 4-methyl-1-pyrindan-5-one
The enamine 7 reacts with crotonic aldehyde in the presence of p-toluenesulphonic acid via the intermediate 8 to yield regioselectively the unknown title compound 9. In alkaline medium, 9 is also formed from 7 and acetylacetaldehyde dimethyl acetal as well as small amounts of 11 and 12; under acidic conditions, however, mixtures of the regioisomers 9/9a are obtained in poor yield. 9a can be separated by fractional crystallisation of the hydrochlorides. Corresponding to 7 the homologous enamine 13 and acetylacetaldehyde acetal by alkaline catalysis gives the 4-methyltetrahydroquinolinone 1, respectively. Improved experimental details for an efficient preparation of the starting compounds 3 and 4 are given.
Reimann,Poschl
p. 589 - 592
(2007/10/02)
More Articles about upstream products of 40459-97-0