| CPC C07D 213/81 (2013.01) | 17 Claims |
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1. A compound of Formula (I):
![]() or a salt thereof, wherein:
R1 is C1-4 alkyl, CH2Cl, phenyl, or benzyl, in which each of phenyl and benzyl may be independently substituted with one, two or three substituents selected from methyl, methoxy, nitro and halogen; and
R2 is C1-4 alkyl; and
wherein the compound comprises less than about 0.5% of the compound of Formula (5):
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