Processes to produce brivaracetam

A process for the preparation of the compound of formula XII from the compound of formula IV,

• wherein, R is saturated or unsaturated C1-20 alkyl or C1alkyl-unsubstituted or substituted aryl, comprising the steps of decarboxylation of the compound of formula IV
• to produce the compound of formula VI
• ring-opening of the compound of formula VI to produce the compound of formula VII
• wherein R1 is saturated or unsaturated C1-20 alkyl or C1alkyl-unsubstituted or substituted aryl;
• and X is Cl, Br, I, OMs, OTs, ONs;
• or
• the compound of formula X
• then converting VII or X by reacting with (S)-2-aminobutanamide or its salt or alkyl (S)-2-aminobutanoate to produce the compound of formula XII, or reacting the compound of formula VI with (S)-2-aminobutanamide or its salt to produce the compound of formula XII in one step;
• or reacting the compound of formula VI with alkyl (S)-2-aminobutanoate to produce XII-a
• wherein R in the compound of formula XII-a is a saturated or unsaturated C1-C20 alkoxyl ;
• and
• then converting XII-a to XII by aminolysis and amide formation reaction.