Water-soluble analogs of compounds intended for the treatment of neurological diseases, epilepsy, neuropathic pain and migraine, and psychiatric disorders, including anxiety and depression, especially suitable for the preparation of oral or parenteral drug forms, are disclosed.

##STR00001##

In one aspect, the invention relates to compounds having the formula:

##STR00001## where R.sup.1-R.sup.6, a, b, and Z are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

In one aspect, the invention relates to compounds having the formula:

##STR00001## where R.sup.1-R.sup.6, a, b, and Z are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

A compound of formula (I), or a salt thereof that may have an antagonistic action against an NMDA receptor that includes an NR2B subunit and may be useful as a prophylactic or therapeutic agent for depression, bipolar disorder, migraine, pain, a symptom peripheral to dementia, or the like.

##STR00001##

A compound of formula (I), or a salt thereof that may have an antagonistic action against an NMDA receptor that includes an NR2B subunit and may be useful as a prophylactic or therapeutic agent for depression, bipolar disorder, migraine, pain, a symptom peripheral to dementia, or the like.

##STR00001##

A compound of formula (I), or a salt thereof that may have an antagonistic action against an NMDA receptor that includes an NR2B subunit and may be useful as a prophylactic or therapeutic agent for depression, bipolar disorder, migraine, pain, a symptom peripheral to dementia, or the like. ##STR00001##

A compound of formula (I), or a salt thereof that may have an antagonistic action against an NMDA receptor that includes an NR2B subunit and may be useful as a prophylactic or therapeutic agent for depression, bipolar disorder, migraine, pain, a symptom peripheral to dementia, or the like. ##STR00001##

Processes for preparing 5,5-dimethyl-3-methylenepyrrolidin-2-one, (S)-3,5,5-trimethylpyrrolidine-2-one, (R)-3,5,5-trimethylpyrrolidine-2-one, (S)-2,4,4-trimethylpyrrolidine, and (R)-2,4,4-trimethylpyrrolidine, and their salt forms are disclosed. ##STR00001##

The invention provides heterocyclic compounds with quaternary centers and methods of preparing compounds. Methods include the method for the preparation of a compound of Formula (II): ##STR00001##
comprising treating a compound of Formula (I): ##STR00002##
with a transition metal catalyst and under alkylation conditions as valence and stability permit.

The invention provides heterocyclic compounds with quaternary centers and methods of preparing compounds. Methods include the method for the preparation of a compound of Formula (II): ##STR00001##
comprising treating a compound of Formula (I): ##STR00002##
with a transition metal catalyst and under alkylation conditions as valence and stability permit.