GB776140A - Lysergic acid derivatives - Google Patents

Abstract

The invention comprises lysergic (and dihydrolysergic) acid derivatives of the general formula <FORM:0776140/IV(b)/1> (wherein R1 represents an alkoxy or mono- or di-alkylamino group, R2 represents -COCH3 or -COCH2.COCH3, and <FORM:0776140/IV(b)/2> represents -CH = C< in the lysergic acid derivatives or -CH2-CH< in the dihydrolysergic acid derivatives), and the preparation thereof by reacting the corresponding compounds unsubstituted on the indole nitrogen atom (i.e. R2 = H) with ketene in the vapour state. The reaction is advantaneously effected with the starting material dissolved in an organic solvent inert to ketene (e.g. benzene, toluene or acetone or mixtures thereof), preferably in a non-polar solvent with the addition of a catalytic amount of a tertiary base (e.g. trimethylamine). In examples, the following starting materials are employed: (1) D-lysergic acid methyl ester; (2) and (3) dihydrolysergic acid methyl ester; (4) D-lysergic acid diethylamide; (5) lysergic acid monoethylamide. The products are useful as pharmaceuticals or intermediates therefor.