A compound that is selected from the group consisting of: 2-{[7-Fluoro-1-methyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-1 H -pyrido[1,2- a]pyrazine-1,6(2 H)-dione; 2-{[1-Ethyl-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-Ethyl-5-(trifluoromethyl)-1 H -pyrrolo[2,3- b]pyridin-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[6-chloro-1-(2,2,2-trifluoroethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-ethyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-methoxy-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(1,1,1-trifluoropropan-2-yl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(trifluoromethoxy)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-methoxy-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1 -yl)-3,4-dihydro-2 H -pyrido[1,2-a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(2,2,2-trifluoroethoxy)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-{4-[4-(prop-2-yn-1-yloxy)benzoyl]benzyl}-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-({5-[(1,3-difluoropropan-2-yl)oxy]-1-methyl-1 H -indol-3-yl}methyl)-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2-a]pyrazine-1,6-dione; and 2-{[1,2-dimethyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; or a pharmaceutically acceptable salt thereof. 2-{[7-Fluoro-1-methyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-1 H -pyrido[1,2- a]pyrazine-1,6(2 H)-dione; 2-{[1-Ethyl-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-Ethyl-5-(trifluoromethyl)-1 H -pyrrolo[2,3- b]pyridin-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[6-chloro-1-(2,2,2-trifluoroethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-ethyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-methoxy-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(1,1,1-trifluoropropan-2-yl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(trifluoromethoxy)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-{[1-methoxy-5-(pentafluoro-λ 6 -sulfanyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H- imidazol-1 -yl)-3,4-dihydro-2 H -pyrido[1,2-a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-methyl-5-(2,2,2-trifluoroethoxy)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 7-(4-methyl-1 H -imidazol-1-yl)-2-{[1-{4-[4-(prop-2-yn-1-yloxy)benzoyl]benzyl}-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione; 2-({5-[(1,3-difluoropropan-2-yl)oxy]-1-methyl-1 H -indol-3-yl}methyl)-7-(4-methyl-1 H- imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2-a]pyrazine-1,6-dione; and 2-{[1,2-dimethyl-5-(trifluoromethyl)-1 H -indol-3-yl]methyl}-7-(4-methyl-1 H -imidazol-1-yl)-3,4-dihydro-2 H -pyrido[1,2- a]pyrazine-1,6-dione;