2-Methylbenzoic acid phenylhydrazide was polylithiated with excess lithium diisopropylamide, and the resulting polylithiated intermediate was condensed with methyl 4-dimethylaminobenzoate or methyl 4-methoxybenzoate to afford C-acylated intermediates that were immediately acid cyclized to afford 3-(4-(dimethylamino)-phenyl)-2-(phenylamino)isoquinolin-1(2 H)-one CHNO or 3-(4-methoxyphenyl)-2-(phenylamino)isoquinolin-1(2 H)-one CHNO. The polylithiated intermediate underwent N-acylation when it was condensed with methyl 4-methylbenzoate to give 2-methyl- N′-(4-methylbenzoyl)- N′-phenylbenzohydrazide CHNO. Crystals of CHNO 4a are triclinic, P $$ \overline{1} $$, a = 9.138(2) Å, b = 10.519(2) Å, c = 11.082(2) Å, α = 91.55(3)°, β = 108.92(3)°, γ = 111.16(3)°, Z = 2, V = 927.1(3) Å, R = 0.0711 and wR = 0.1828 for reflections with I > 2σ( I); crystals of CHNO 4b are monoclinic, P2/ c, a = 8.821(1) Å, b = 13.276(2) Å, c = 15.482(3) Å, β = 105.271(4)°, Z = 4, V = 1748.9(5) Å, R = 0.0416 and wR = 0.1030 for reflections with I > 2σ( I); crystals of CHNO 3 are orthorhombic, Pbca, a = 13.505(3) Å, b = 9.733(2) Å, c = 28.601(6) Å, Z = 8, V = 3759.4(13) Å, R = 0.1683 and wR = 0.3526 for reflections with I > 2σ( I). Index Abstract: X-ray crystal analysis was important for the confirmation of the structure of 3-(4-(dimethylamino)phenyl)-2-(phenylamino)isoquinolin-1(2 H)-one CHNO 4a, 3-(4-methoxyphenyl)-2-(phenylamino)isoquinolin-1(2 H)-one CHNO 4b, and 2-methyl- N′-(4-methylbenzoyl)- N′-phenylbenzohydrazide CHNO 3 prepared from polylithiated 2-methylbenzoicacid phenylhydrazide and methyl 4-dimethylaminobenzoate, methyl 4-methoxybenzoate, or methyl 4-methylbenzoate. Crystals of CHNO 4a are triclinic, P $$ \overline{1} $$, a = 9.138(2) Å, b = 10.519(2) Å, c = 11.082(2) Å, α = 91.55(3)°, β = 108.92(3)°, γ = 111.16(3)°, Z = 2, V = 927.1(3) Å, R = 0.0711 and wR = 0.1828 for reflections with I > 2σ( I); crystals of CHNO 4b are monoclinic, P2/ c, a = 8.821(1) Å, b = 13.276(2) Å, c = 15.482(3) Å, β = 105.271(4)°, Z = 4, V = 1748.9(5) Å, R = 0.0416 and wR = 0.1030 for reflections with I > 2σ( I); crystals of CHNO 3 are orthorhombic, Pbca, a = 13.505(3) Å, b = 9.733(2) Å, c = 28.601(6) Å, Z = 8, V = 3759.4(13) Å, R = 0.1683 and wR = 0.3526 for reflections with I > 2σ( I). [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]