A compound of Formula wherein R 1 is selected from the group consisting of phenyl, pyridinyl, and thiazolyl; wherein R 1 is optionally substituted with one to two substituents independently selected from the group consisting of C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, hydroxy, fluoro, chloro, bromo, and cyano; in addition, R 1 is optionally substituted with amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, aminocarbonyl, C 1-4 alkylaminocarbonyl, or di(C 1-4 alkyl)aminocarbonyl; Y is O, S, NH, vinyl, ethynyl or S; R 2 is a substituent selected from the group consisting of hydrogen, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, fluoro, chloro, bromo, and hydroxy; R a is hydrogen or methyl; R 3 is selected from the group consisting of pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-2-ylmethyl, piperidin-3-ylmethyl, piperidin-4-ylmethyl, piperidin-2-ylethyl, piperidin-3-ylethyl, piperidin-4-ylethyl, pyridin-4-yl-(C 1-2)alkyl, azetidin-3-ylmethyl, morpholin-2-ylmethyl, morpholin-3-ylmethyl, imidazolylmethyl, thiazolylmethyl, (amino)-C 3-6 cycloalkyl, 3-hydroxy-2-amino-propyl, 8-aza-bicyclo[3.2.1]octanyl, 1-aza-bicyclo[2.2.2]octanyl, guanidinyl-ethyl, 4-(imidazol-1-yl)-phenylmethyl, 2-(methylamino)-ethyl, 2-diethylamino-ethyl, 4-diethylamino-but-2-yl, piperidin-3-yl, piperidin-4-yl, and pyrrolidin-3-yl; and wherein piperidin-3-yl is optionally substituted at a carbon atom with phenyl; and wherein pyrrolidin-2-yl of pyrrolidin-2-ylmethyl, pyrrolidin-3-yl, piperidin-3-yl, and piperidin-4-yl are optionally substituted at a nitrogen atom with methyl, phenylmethyl, phenethyl, or methylcarbonyl; and enantiomers, diastereomers, and pharmaceutically acceptable salts thereof. R 1 is selected from the group consisting of phenyl, pyridinyl, and thiazolyl; wherein R 1 is optionally substituted with one to two substituents independently selected from the group consisting of C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, hydroxy, fluoro, chloro, bromo, and cyano; in addition, R 1 is optionally substituted with amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, aminocarbonyl, C 1-4 alkylaminocarbonyl, or di(C 1-4 alkyl)aminocarbonyl; Y is O, S, NH, vinyl, ethynyl or S; R 2 is a substituent selected from the group consisting of hydrogen, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, fluoro, chloro, bromo, and hydroxy; R a is hydrogen or methyl; R 3 is selected from the group consisting of pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-2-ylmethyl, piperidin-3-ylmethyl, piperidin-4-ylmethyl, piperidin-2-ylethyl, piperidin-3-ylethyl, piperidin-4-ylethyl, pyridin-4-yl-(C 1-2)alkyl, azetidin-3-ylmethyl, morpholin-2-ylmethyl, morpholin-3-ylmethyl, imidazolylmethyl, thiazolylmethyl, (amino)-C 3-6 cycloalkyl, 3-hydroxy-2-amino-propyl, 8-aza-bicyclo[3.2.1]octanyl, 1-aza-bicyclo[2.2.2]octanyl, guanidinyl-ethyl, 4-(imidazol-1-yl)-phenylmethyl, 2-(methylamino)-ethyl, 2-diethylamino-ethyl, 4-diethylamino-but-2-yl, piperidin-3-yl, piperidin-4-yl, and pyrrolidin-3-yl; and wherein piperidin-3-yl is optionally substituted at a carbon atom with phenyl; and wherein pyrrolidin-2-yl of pyrrolidin-2-ylmethyl, pyrrolidin-3-yl, piperidin-3-yl, and piperidin-4-yl are optionally substituted at a nitrogen atom with methyl, phenylmethyl, phenethyl, or methylcarbonyl; and enantiomers, diastereomers, and pharmaceutically acceptable salts thereof.