Reaction of methyl-2-(2-formylphenyl)acetate with primary amines in a reductive amination/cyclisation process resulted in N-substituted 1,4-dihydro-3(2H)-isoquinolinones. With H₂NCH₂R sodium borohyride is a suitable reductant (11 examples), but H₂NCHR¹R² required a transfer hydrogenation using ammonium formate catalysed by palladium on carbon (9 examples). 4-Substituted-1,4-dihydro-3(2H)-isoquinolinones were synthesised by deprotonation (n-butyllithium) and addition of R³CH₂Br (12 examples with R³ = alkyl, Ar, CHCH₂, CCH). Modest diastereoselectivity was achieved with 1,4-dihydro-3(2H)-isoquinolinones derived from H₂NCHMeR² [R² = (η⁵-C₅H₄)Co(η⁴-C₄Ph₄) - max. dr = 1.9 : 1], but use of H₂NCHMeFc (Fc = ferrocenyl) provided a new method of 1,4-dihydro-3(2H)-isoquinolinone N-deprotection with formic acid.

在还原胺化/环化过程中，2-(2-甲酰基苯基)乙酸甲酯与伯胺的反应产生N-取代的 1,4-二氢-3(2H)-异喹啉酮。H ₂ NCH ₂ R 硼氢化钠是合适的还原剂（11 个实施例），但 H ₂ NCHR ¹ R ²需要使用由披钯碳催化的甲酸铵进行转移氢化（9 个实施例）。通过去质子化（正丁基锂）和添加 R ³ CH ₂ Br（12 个实例，其中 R ³  = 烷基、Ar、CH CH ₂、C ）合成了 4-取代的-1,4-二氢-3(2H)-异喹啉酮CH）。使用衍生自 H ₂ NCHMeR ² [R ²  = (η ⁵ -C ₅ H ₄ )Co(η ⁴ -C ₄ Ph ₄ ) - max. 的1,4-二氢-3(2H)-异喹啉酮获得适度的非对映选择性。dr = 1.9 : 1]，但使用 H ₂ NCHMeFc（Fc = 二茂铁）提供了一种用甲酸进行 1,4-二氢-3(2H)-异喹啉酮N-脱保护的新方法。