Reductive amination of 4,5-dimethoxy-9,10-dioxo-9,10-dihydroanthracene-2- carbaldehyde derived from aloe-emodin/Aminacion reductiva del 4,5-dimetoxi-9,10-dioxo-9,10- dihidroantraceno-2-carbaldehido derivado de aloe-emodin

The reductive amination of the 1,8-O-protected aloe-emodin carbaldehyde to obtain amino derivatives using different reducing agents and conditions is reported in this article. Aldehyde was obtained in good yield using manganese dioxide as oxidizing agent. The synthesis of two new imines derived from 1,8-O-dimethyl aloe-emodin carbaldehyde is reported as well in good yields. Sodium borohydride in methanolgave the best conversions as reducing agent for the reductive amination and the conditions were adjusted to increase the conversion to 59 % of the desired product. Same results were obtained starting from the aldehyde or from the imine, in a stepwise or an indirect reductive amination respectively.