Aminomethylation of chlorophyll a derivatives using bis(N,N-dimethylamino)methane

Bis(N,N-dimethylamino)methane has been shown to be a convenient reagent for the aminomethylation of chlorophyll a derivatives. Methylpheophorbide a (in enol form) and chlorin c(6) 13-amides were aminomethylated with bis(N,N-dimethylamino) methane. Reactivity of methylpheophorbide a exo-ring and chlorin e(6) 13-amides vinyl group were shown to be different. Selective methyl pheophorbide a exo-ring aminomethylation was realized and isomerization of the exo-ring amino methylation product with rhodochlorin 15-acrylic derivative formation was studied. The action of bis(N,N-dimethylamino)methane in the presence of weak acid has been shown to be a simple and effective synthetic procedure to obtain a new chlorin e(6) derivative with two N,N-dimethylaminomethyl substituents in the vinyl group. The aminomethylation products' high yields, the simplicity of the procedure, the use of metal-free chlorines and the possible synthesis of new compounds, were found to be the main advantages of using bis(N,N-dimethylamino) methane as an aminomethylation reagent in chlorophyll a derivatives' chemistry.