Conventional organic synthesis entails a sequence of linear steps, in which one sets up a reaction, works up the reaction, and purifies the reaction mixture to isolate the desired product. This three step process (i.e., reaction setup, work-up, purification) is then repeated until the target molecule is attained.
Aldehydes, being one of the most versatile functional groups, are often intermediates in conventional organic syntheses. It is fairly common to make use of reagents that are air/water sensitive, pyrophoric, toxic or corrosive to functionalize aldehyde intermediates. It is also common to employ chiral transition metal catalysts to carry out asymmetric transformations of aldehydes.
The goal of our research is to access useful synthetic building blocks, while: 1) avoiding the use of reagents that are air/water sensitive, pyrophoric, toxic and corrosive, and 2) minimizing the cost, waste, and time associated with conventional organic synthesis. Our approach is to develop cascade reactions, in which multiple synthetic steps are carried out in a single flask. Since a work-up and purification of each discreet synthetic transformation is not required, cascade reactions can greatly reduce the time, cost and waste (i.e., solvents, silica gel) associated with organic synthesis. The development of these cascade reactions is possible through the use of organocatalysts, which are organic compounds that catalyze reactions. The unique mechanisms by which organocatalysts operate facilitate the combination of multiple functionalizations of aldehyde substrates into a single flask. Moreover, the unique mechanisms by which organocatalysts operate enable functionalizations of aldehyde substrates that cannot effectively be achieved using transition metal-catalyzed reactions, and without the use of conventional reagents that may be air/water sensitive, pyrophoric, toxic or corrosive.
We therefore consider organocatalyzed cascade reactions to be green chemical methods to rapidly build molecular complexity. Some examples of our work are illustrated below.
...Results coming soon!