Organocatalyst is an environmentally benign catalyst. Our group[1] and Jorgensen’s group[2]
independently discovered that diphenylprolinol silyl ether is an effective organocatalyst in the
reaction involving enamine and iminium ion as reactive intermediates.
On the other hand, one-pot operations are an effective method for both carrying out several
transformations and forming several bonds in a single-pot, while at the same time cutting out
several purifications, minimizing chemical waste generation, and saving time. Thus, a one-pot
reaction can be not only efficient, but also green and environmentally friendly, and “poteconomy”
should be considered in planning a synthesis.[3]
We have been investigating the application of this organocatalyst to the one-pot synthesis
of biologically active molecules. Quinine is one of the cinchona alkaloids. It is an important
antimalarial medication, and its derivatives are used not only as ligands of asymmetric metal
catalysts, but also as effective asymmetric organocatalysts. Thus, it is important to develop an
efficient method for the synthesis of quinine. Using diphenylprolinol silyl ether-mediated
asymmetric Michael reaction, we can construct a chiral piperidine skeleton with excellent
diastereo- and enantioselectivities by three component coupling reaction in a single reaction
vessel. By employing one-pot