3-aryl-3-hydroxy-2-amino-propionic acid amides, 3-heteroaryl-3-hydroxy-2-amino-propionic acid amides and related compounds having analgesic and/or immuno stimulant activity

1. A method of treating chronic pain a mammal in need of such treatment, comprising administering to said mammal at least one compound of the formula

or a pharmaceutically acceptable salt thereof, wherein:

R 1 is H or alkyl of 1 to 6 carbons;

R 2 is selected from the group consisting of H, and alkyl of 1 to 6 carbons; or the R 1 and R 2 groups together with the nitrogen atom to which they are shown attached form a saturated or unsaturated 4, 5, 6 or 7 membered ring that optionally additionally includes one or two heteroatoms independently selected from the group consisting of N, O and S, said 4, 5, 6 or 7 membered ring optionally being substituted with one or two COOH, CH 2 OH, OH, B(OH) 2 , halogen groups, cyano groups or with one or two alkyl groups having 1 to 6 carbons;

R 3 is H, CO—R 7 or CO—O—R 7 where R 7 is H, alkyl of 1 to 1 to 20 carbons, cycloalkyl of 3 to 6 carbons, aryl or heteroaryl, aryl-alkyl, aryl(hydroxy)alkyl, heteroaryl-alkyl or heteroalkyl(hydroxy)alkyl where the alkyl moiety has 1 to 4 carbons, said aryl or heteroaryl groups being optionally substituted with 1 to 3 groups independently selected from the group consisting of halogen, alkyl of 1 to 6 carbons, alkoxy of 1 to 6 carbons and thioxy of 1 to 3 carbons;

R 4 is H, alkyl of 1 to 6 carbons, or CO—R 8 where R 8 is alkyl of 1 to 6 carbons;

R 5 and R 6 are independently selected from the group consisting of H, halogen, alkyl of 1 to 6 carbons, alkoxy of 1 to 6 carbons and thioxy of 1 to 3 carbons; or

R 5 and R 6 together with the atoms to which they are attached jointly form a carbocyclic or a heterocyclic ring, the carbocyclic ring having 5 or 6 atoms in the ring, the heterocyclic ring having 5 or 6 atoms in the ring and 1 to 3 heteroatoms independently selected from N, O and S;

said carbocyclic or heterocyclic ring jointly formed by R 5 and R 6 being optionally substituted with 1 to 6 R 9 groups where R 9 is independently selected from halogen, alkyl of 1 to 6 carbons, alkoxy of 1 to 6 carbons, and

the wavy lines represent bonds of the alpha or beta configuration; and wherein said chronic pain is associated with peripheral neuropathy.

2. A method of treating chronic pain a mammal in need of such treatment, comprising administering to said mammal at least one compound of the formula

or a pharmaceutically acceptable salt of said compound, wherein:

R 1 and R 2 groups together with the nitrogen atom to which they are shown attached form a saturated 5 or 6 membered ring, said ring optionally being substituted with one or two COOH, CH 2 OH, OH, B(OH) 2 , halogen groups, cyano groups or with one or two alkyl groups having 1 to 6 carbons;

R 3 is H or alkyl of 1 to 20 carbons; and

R 4 is H or alkyl of 1 to 6 carbons; and wherein said chronic pain is associated with peripheral neuropathy.

3. A method of treating chronic pain a mammal in need of such treatment, comprising administering to said mammal at least one compound of the formula

or any other pharmaceutically acceptable salt of

and wherein said chronic pain is associated with peripheral neuropathy.

4. A method of treating chronic pain a mammal in need of such treatment, comprising administering to said mammal at least one compound of the formula

or a pharmaceutically acceptable salt thereof; wherein said chronic pain is associated with peripheral neuropathy.