Piperidine derivatives and process for their production
View Patent ↗The present invention relates to substantially pure piperidine derivative compounds of the formulae: wherein R 1 is hydrogen or hydroxy; R 2 is hydrogen; or R 1 and R 2 taken together form a second bond between the carbon atoms bearing R 1 and R 2 ; R 3 is —COOH or —COOR 4 ; R 4 has 1 to 6 carbon atoms; A, B, and D are the substituents of their respective rings, each of which may be different or the same and are hydrogen, halogens, alkyl, hydroxy, alkoxy, or other substituents. A process of preparing such piperidine derivative compounds in substantially pure form is also disclosed.
1. A compound of the formula:
wherein
A is one or more substituents, each of which may be different or the same, and are selected from the group consisting of hydrogen, halogens, alkyl, hydroxy or alkoxy;
R 5 is —N(R 6 ) 2 ; and
R 6 is an alkyl with 1 to 6 carbons.
2. A process of preparing a mixture of regioisomers of the formula:
wherein
A is one or more substituents, each of which may be different or the same, and are selected from the group consisting of hydrogen, halogens, alkyl, hydroxy or alkoxy;
R 5 is —N(R 6 ) 2 ; and
R 6 is an alkyl with 1 to 6 carbons;
said process comprising:
acylating a starting compound of the formula:
with a compound of the formula:
wherein
X is a halogen.
3. A process according to claim 2 , wherein said acylating is carried out by a Friedel-Crafts reaction using AlCl 3 catalyst.