Disclosed are compounds of Formulas (I), (II), (III), (IV), and (V):

##STR00001##

and/or a salt thereof, wherein R.sub.1 is OH or OP(O)(OH).sub.2, and X.sub.1, X.sub.2, X.sub.3, R.sub.2, R.sub.2a, R.sub.a, R.sub.b, and R.sub.c are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P.sub.1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.

Disclosed are compounds of Formulas (I), (II), (III), (IV), and (V): ##STR00001##
and/or a salt thereof, wherein R.sub.1 is OH or OP(O)(OH).sub.2, and X.sub.1, X.sub.2, X.sub.3, R.sub.2, R.sub.2a, R.sub.a, R.sub.b, and R.sub.c are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P.sub.1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.

Disclosed are compounds of Formulas (I), (II), (III), (IV), and (V): ##STR00001##
and/or a salt thereof, wherein R.sub.1 is OH or OP(O)(OH).sub.2, and X.sub.1, X.sub.2, X.sub.3, R.sub.2, R.sub.2a, R.sub.a, R.sub.b, and R.sub.c are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P.sub.1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.

Compounds of formula (I), wherein R.sub.1 is as defined in the claims, exhibit COMT enzyme inhibiting activity and are thus useful as COMT inhibitors. Methods of treatment and pharmaceutical dosage forms are also disclosed.

Disclosed are compounds of Formulas (I), (II), (III), (IV), and (V):

##STR00001##

and/or a salt thereof, wherein R.sub.1 is OH or OP(O)(OH).sub.2, and X.sub.1, X.sub.2, X.sub.3, R.sub.2, R.sub.2a, R.sub.a, R.sub.b, and R.sub.c are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P.sub.1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.

Stereoselective and regioselective synthesis of compounds via nucleophilic ring opening reactions of aziridinium ions for use in stereoselective and regioselective synthesis of therapeutic and diagnostic compounds.

Stereoselective and regioselective synthesis of compounds via nucleophilic ring opening reactions of aziridinium ions for use in stereoselective and regioselective synthesis of therapeutic and diagnostic compounds.