Acetylene Derivatives

A compound of formula (I′)

• wherein
• R1 represents hydrogen or C1-C4 alkyl and
• R2 represents an unsubstituted or substituted heterocycle or
• R1 represents hydrogen or C1-C4 alkyl and
• R2 represents aryl or substituted aryl or
• R1 and R2 together with the nitrogen atom form an unsubstituted or substituted heterocycle;
• R3 represents (C1-4)alkyl, (C1-4)alkoxy, trifluoromethyl, halogen, cyano, nitro, —CHO, —COO(C1-4)alkyl, —CO(C1-4)alkyl.

A compound of formula (II)

• wherein
• R3 represents (C1-4)alkyl, (C1-4)alkoxy, trifluoromethyl, halogen, cyano, nitro, —CHO, —COO(C1-4)alkyl, —CO(C1-4)alkyl;
• N represents 0, 1, 2, 3, 4 or 5;
• R5 and R6 represent H or C1-C4 alkyl.

A process for the preparation of a compound of formula (I)

• wherein
• R1 represents hydrogen or C1-C4 alkyl and
• R2 represents an unsubstituted or substituted heterocycle or
• R1 represents hydrogen or C1-C4 alkyl and
• R2 represents aryl or substituted aryl or
• R1 and R2 together with the nitrogen atom form an unsubstituted or substituted heterocycle;
• R3 represents (C1-4 alkyl (C1-4) alkoxy trifluoromethyl, halogen, cyano, nitro, —CHO, —COO(C1-4)alkyl, —CO(C1-4)alkyl;
• n represents 0, 1, 2, 3, 4 or 5;
• R4 represents OH and
• R5 and R6 represent H or C1-C4 alkyl or
• R4 and R5 form a bond and
• R6 represent H or C1-C4 alkyl or
• R4 and R6 form a bond and
• R5 represent H or C1-C4 alkyl;
• in free base or acid addition salt form, comprising:
• a)for the production of a compound of formula (I) wherein i) R4 represents hydroxy, R1 represents hydrogen or C1-C4 alkyl and R2 represents an unsubstituted or substituted heterocycle or ii) R1 represents hydrogen or C1-C4 alkyl and R2 represents aryl or substituted aryl, by reductive amination of a compound of formula (II)
• wherein R6, R5, R3, n are as defined above, with a compound of formula (III)
• wherein R1 and R2 are as defined above, or
• b) for the production of a compound of formula (I) wherein R4 represents hydroxy, R1 and R2 together with the nitrogen atom form an unsubstituted or substituted heterocycle, by cyclocondensation of a compound of formula (IV)
• c) for the production of a compound of formula (I) wherein R4 represents hydroxy, R1 and R2 together with the nitrogen atom form an unsubstituted or substituted heterocycle, by reductive alkylation of a compound of formula (V)
• wherein R6, R5, R2, R1 are as defined above, with a compound of formula (VI) with a compound of formula (VI)
• wherein R3 and n are as defined above, or
• d) for the production of a compound of formula (I) wherein i) R4 and R5 form a bond and R6 represents hydrogen or C1-C4 alkyl or ii) wherein R4 and R6 form a bond and R5 represents hydrogen, by dehydrating a compound of formula (I) wherein R4 is hydroxyl R5 and R6 are hydrogen or C1-C4 alkyl;
• and recovering the resulting compound of formula (I) in free base or acid addition salt form.