Process for preparation of risdiplam, novel intermediates, and process for preparation thereof

(canceled)

A process for the preparation of 1-formyl-4,7-diazaspiro[2,5]octane (Formula-3) which comprises:

• a) reacting 7-benzyl-4,7-diazaspiro[2,5]octane with formic acid in the presence of a hydrocarbon solvent to obtain 7-benzyl-1-formyl-4,7-diazaspiro[2,5]octane (Formula-2);
• and
• b) hydrogenating the 7-benzyl-1-formyl-4,7-diazaspiro[2,5]octane (Formula-2) in the presence of a catalyst and an alcoholic solvent to obtain 1-formyl-4,7-diazaspiro[2,5]octane (Formula-3)

(canceled)

(canceled)

Novel intermediate compounds for the synthesis of Risdiplam selected from the group consisting of 7-benzyl-1-formyl-4,7-diazaspiro[2,5]octane (Formula-2), 1-formyl-4,7-diazaspiro[2,5]octane (Formula-3) and 7-(4-formyl-4,7-diazaspiro[2,5]octan-7-yl)-2-(2,8-dimethylimidazo{1,2-b]pyridazin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (Formula-4), alkyl/aryl-7-benzyl-4,7-diazaspiro[2,5]octane-1-carboxylate (Formula-5), alkyl/aryl-4,7-diazaspiro[2,5]octane-1-carboxylate (Formula-6) and 7-(4-alkoxycarbonyl)-4,7-diazaspiro[2,5]octan-7-yl)-2-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (Formula-7) as depicted below