Salt-Free CatAnionic Vesicular Nanoreactor from Dithiocarbamate: Michael Addition of Nitroolefins in Aqueous Vesicle System

The salt-free CatAnionic vesicle was previously generated by mixing cationic and anionic amphiphiles, and removing the salt that occurred as a side product from the mixture. In this study, we report a new strategy to produce the salt-free CatAnionic vesicle of N,N-dialkylamonium N,N dialkyldithiocarbamate (AmDTC) through a one-step condensation between secondary amine and carbon disulfide. Both dialkylammonium cationic and dithiocarbamate anionic amphiphiles were generated concurrently during the condensation. The AmDTC was dispersed in water, resulting in the spontaneous formation of salt-free CatAnionic vesicles. Among several AmDTCs, the N,N-didodecylamonium N,N-didodecyldithiocarbamate (AmDTC-C12C12) showed high stability and was applied as a vesicular nanoreactor for the Michael addition in water. Michael addition in an aqueous system between nitroolefins and 1,3-dicarbonyl compounds afforded the desired twenty-three Michael adducts, with yields ranging from 65% to 92%. It is hypothesized that the AmDTC-C12C12 serves as a vesicular nanoreactor and plays a role in catalysis at the dithiocarbamate functional group. Preparative-scale and one-pot Michael addition by in situ generation of AmDTC-C12C12 vesicle afforded the Michael adducts also in good yields. The AmDTC-C12C12 vesicular nanoreactor was applied for the synthesis of (±)-baclofen with 54% yields over three steps. The reusability of the AmDTC-C12C12 was demonstrated and allowed the reuse of the CatAnionic vesicle up to seven cycles. Finally, chemical recycling was demonstrated by converting AmDTC-C12C12 to N,N-didodecylammonium chloride by simple acidification.