Core Scaffold-Inspired Stereoselective Synthesis of Spiropyrazolones via an Organocatalytic Michael/Cyclization Sequence

摘要

Herein, the organocatalytic asymmetric Michaelcyclization sequence of α-isothiocyanato imides and esters with anvariety of unsaturated pyrazolones is presented, in general,naffording functionalized spiropyrazolones containing threencontiguous stereogenic centers in high levels of diastereo- andnenantioselectivity (up to 20:1 dr and 99% ee). Moreover, thencurrent protocol provides a highly efficient and convenientnstrategy that allows rapid enantioselective construction ofndiversely spiropyrazolone skeletons with high optical purity.