A compound of Formula I ** (See formula) ** in which: R1 is hydrogen, alkyl or cycloalkyl； R2 is hydrogen or alkyl； R3 is hydrogen, alkyl or halo； R4 is (R7) -piperazinyl or Ar1； R5 is absent or is Ar2； or R5 is azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, homopiperidinyl, homopiperazinyl or homomorpholinyl, and is substituted by 0-3 substituents selected from halo, alkyl and oxetanyl； R6 is cycloalkyl or Ar3； R7 is hydrogen or alkyl； Ar1 is phenyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, indazolyl, triazolyl or quinolinyl, and is substituted by 0-3 alkyl substituents； Ar2 is phenyl, pyridinyl, ((R7) -piperazinyl) pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, indazolyl, pyrazolopyridinyl, benzotriazolyl, quinolinyl or aminoquinolinyl, and is substituted by 0-3 alkyl substituents； Ar3 is phenyl, chromanyl or dihydrobenzoxazinyl, and is substituted by 0-3 substituents selected from cyano, halo, alkyl, haloalkyl, alkoxy and haloalkoxy； X1 is CH, CH2, O, S or NR7； X2 is alkylene or alkenylene； and X3 is CH, CH2, CH2O O, S or NR5； or a pharmaceutically acceptable salt thereof.Un compuesto de Fórmula I **(Ver fórmula)** en la que: R1 es hidrógeno, alquilo o cicloalquilo； R2 es hidrógeno o alquilo； R3 es hidrógeno, alquilo o halo； R4 es (R7)-piperazinilo o Ar1； R5 está ausente o es Ar2； o R5 es azetidinilo, pirrolidinilo, piperidinilo, piperazinilo, morfolinilo, homopiperidinilo, homopiperazinilo u homomorfolinilo, y está sustituido por 0-3 sustituyentes seleccionados entre halo, alquilo y oxetanilo； R6 es cicloalquilo o Ar3； R7 es hidrógeno o alquilo； Ar1 es fenilo, piridinilo, pirazinilo, pirimidinilo, piridazinilo, indazolilo, triazolilo o quinolinilo, y está sustituido por 0-3 sustituyentes alquilo； Ar2 es fenilo, piridinilo, ((R7)-piperazinil)piridinilo, pirazinilo, pirimidinilo, piridazinilo, indazolilo, pirazolopiridinilo, benzotriazolilo, quinolinilo o aminoquinolinilo, y está sustituido por 0-3 sustituyentes alquilo； Ar3 es fenilo, cr
