Disclosed are compounds of Formula (I): (I) or stereoisomers, salts, or prodrugs thereof, wherein: (i) R1 and R2 are independently C1-C4 alkyl, or (ii) R1 and R2 together with the carbon atom to which they are attached, form a cyclic group; and Q is H, C1-6alkyl, phenyl or 5- to 6-membered heteroaryl substituted with zero to 3 substituents, and G is defined herein. Also disclosed are method of using such compounds as selective agonists for G protein-coupled receptor S1P1, and pharmaceutical compositions comprising such compounds. There 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 chronic inflammatory disease.