A compound of Formula I: ** Formulas ** in which: -Y-Z- is -C (>； = NR4) -NR2 - or -C (NR5R6)>； = N-； R1 is aryl, cycloalkyl, cycloalkenyl, heterocyclyl or heteroaryl； wherein said aryl, cycloalkyl, cycloalkenyl, heterocyclyl or heteroaryl are optionally substituted with one, two or three substituents independently selected from the group consisting of halo, -NO2, -CN, -SF5, -Si (CH3) 3, -O -R20, -S-R20, -C (O) -R20, -C (O) -OR20, -N (R20) (R22), -C (O) -N (R20) (R22), -N ( R20) -C (O) -R22, -N (R20) - C (O) -OR22, -N (R20) -S (>； = O) 2-R26, -S (>； = O) 2-R20, -OS (-O) 2-R20, -S (>； = O) 2-N (R20) (R22), C1-6 alkyl, C2-4 alkenyl, C2-4 alkynyl, cycloalkyl, aryl, heteroaryl and heterocyclyl； and wherein said C1-6 alkyl, C2-4 alkenyl, C2-4 alkynyl, cycloalkyl, aryl, heteroaryl or heterocyclyl are optionally substituted with one, two or three substituents independently selected from the group consisting of halo, -NO2, phenyl , heterocyclyl, heteroaryl, C1-6 alkyl, cycloalkyl, -N (R20) (R22), -C (O) -R20, -C (O) -OR20, -C (O) -N (R20) (R22) , -CN and -O-R20； R2 is hydrogen, alkyl, -C (O) -R20, -C (O) -OR26, -C (O) -N (R26) (R26), -N (R20) -S (>； = O) 2- R20, cycloalkyl, aryl, heteroaryl or heterocyclyl； wherein said C1-6 alkyl, cycloalkyl, aryl, heteroaryl or heterocyclyl are optionally substituted with one, two or three substituents independently selected from the group consisting of C1-6 alkyl, C2-4 alkynyl, halo, -NO2, cycloalkyl, aryl, heterocyclyl, heteroaryl, -N (R20) (R22), -C (O) -R20, -C (O) -OR20, -C (O) - N (R20) (R22), -CN, oxo and -O-R20； wherein said C1-6 alkyl, cycloalkyl, aryl, heterocyclyl or heteroaryl are additionally optionally substituted with one, two or three substituents independently selected from the group consisting of halo, -NO2, C1-6 alkyl, cycloalkyl, aryl, heterocyclyl, heteroaryl, -N (R20) (R22), -C (O) -R20, -C (O) -OR20, -C (O) - N (R20) (R22), -CN and -O-R20； and wherein said C1-6 alkyl, cycloalkyl, aryl, heterocyclyl or he
