The invention provides methods of synthesizing a viral protease inhibitor in high yield, without using expensive catalysts or challenging reaction conditions.

The invention provides methods of synthesizing a viral protease inhibitor in high yield, without using expensive catalysts or challenging reaction conditions.

The present disclosure discloses prodrugs of gamma-hydroxybutyric acid as well as compositions and uses thereof.

The present disclosure discloses prodrugs of gamma-hydroxybutyric acid as well as compositions and uses thereof.

The present disclosure discloses prodrugs of gamma-hydroxybutyric acid as well as compositions and uses thereof.

The present disclosure discloses prodrugs of gamma-hydroxybutyric acid as well as compositions and uses thereof.

The invention provides methods of synthesizing a viral protease inhibitor in high yield, without using expensive catalysts or challenging reaction conditions.

The invention provides methods of synthesizing a viral protease inhibitor in high yield, without using expensive catalysts or challenging reaction conditions.

The invention provides methods of synthesizing a viral protease inhibitor in high yield, without using expensive catalysts or challenging reaction conditions.

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.