Novel compounds of structure Formula I: or an enantiomer, a diastereomer, or a pharmaceutically acceptable salt thereof, wherein n1, R1, R2, R3 and R4 are defined herein, are provided which are GPR119 G protein-coupled receptor modulators. GPR119 G protein-coupled receptor modulators are useful in treating, preventing, or slowing the progression of diseases requiring GPR119 G protein-coupled receptor modulator therapy. Thus, the disclosure also concerns compositions comprising these novel compounds and methods of treating diseases or conditions related to the activity of the GPR119 G protein-coupled receptor by using any of these novel compounds or a composition comprising any of such novel compounds.