Alkaloid-Derived Thioureas in Asymmetric Organocatalysis: A Cooperative Learning Activity in a Project-Based Laboratory Course

摘要

An experiment carried out by advanced undergraduate students in a project-based laboratory course is described. Taking into account the positive effects of working in teams, which has been key for successful research in industry and academia, a cooperative learning experience in the laboratory was developed. Students working in teams of four synthesize two alkaloid-derived thioureas starting from a chiral pool (quinidine and quinine). The thioureas are used to catalyze an enantioselective Michael reaction between acetylacetone and trans-4-methyl-beta-nitrostyrene, providing a platform for discussion of stereochemistry and chirality transfer events. Qualitative analysis of the reaction enantioselectivity is performed by polarimetry, which allows students to assign product optical rotations (+/-) with their absolute configurations (S/R). Students are exposed to an entire research process: analysis of primary literature, discussion with colleagues, planning laboratory schedules, and execution of experiments.