“…There are many published articles on the different reactions of ninhydrin, such as amidoalkylation, 60 Knoevenagel condensation, 61 oxidation, [62][63] reduction, [64][65][66] aldol addition, [67][68][69][70][71][72][73][74] cycloaddition, 75 Friedel-Crafts type reaction, [76][77][78][79][80][81][82][83] Kolbe-Schmitt, 84 Passerini, [85][86][87][88][89][90][91][92] Wittig, [93][94][95][96][97][98][99][100][101][102][103][104][105][106] and Morita-Baylis-Hillman reactions. [107][108][109]…”