Table 8. Reaction Scope (Scheme 7)^a.

^aReaction conditions: All reactions were carried out with ninhydrin (10 mmol, 1.0 equiv, 1.8 g) (Scheme 7) by stirring in a solvent mixture of CH₃COOH (10 mL) and CH₃OH (30 mL) with a 1:3 ratio for 30 min at RT. Isolated yields are reported for 2a.