Abstract
3, 4-Dihydro-1, 2-tetramethylene-β-carboline (I) was synthesized from 2-(2'-pyridyl) indole by a new method.The latter, when treated with fromaldehyde and diethylamine, readily geve the β-diethylaminomethyl derivative (III) in a fair yield. Its methiodide (V), made advantageously via the corresponding methosulfate (IV), was reacted with aqueous alkali cyanide to give the indolylacetonitrile (VI), which was hydrolysed and esterified, giving the indolylacetic ester (VIII). LiAlH4-reduction of this ester yielded the β-hydroxyethyl derivative (IX), which gave directly the β-carbolinium bromide (X) by the agency of PBr3, catalytic reduction of which gave (I) in a smooth reaction. The hitherto unknown 2-(3'-pyridyl)-and 2-(4'-pyridyl)-indoles, their metho-salts and the corresponding 2-piperidyl indoles were also prepared.
