Process for preparing 6-substituted-1-(2H)-isoquinolinones and intermediate compound

A process for the preparation of a compound of the formula

• wherein
• n is 1, 2, 3 or 4;
• and
• R1 is H or a protecting group,
• comprising
• (B) reacting a compound of formula (IV)
• wherein R1 is a protecting group
• with a mixture of a reagent of the formula (R2O)2HC—N(CH3)2 (V), wherein R2 is (C1-C6)alkyl, and pyrrolidine,
• wherein reagent (V) is used in a molar excess of 1.5 or more equivalents and the pyrrolidine is used in a molar excess of 4.0 or more equivalents over a compound of formula (IV);
• and
• optionally removing the protection group in a compound of formula (VI) to give a compound of formula ((VI) wherein R1 is H.