Squaramide-catalysed asymmetric Michael addition/cyclization cascade reaction of 4-arylmethylidene-2,3-dioxopyrrolidines with 2-isothiocyanato-1-indanones.

A highly efficient cinchona alkaloid-derived squaramide catalysed asymmetric Michael/cyclization cascade reaction of 4-arylmethylidene-2,3-dioxopyrrolidines with 2-isothiocyanato-1-indanones was successfully developed. This protocol provides an efficient and mild access to indanone-derived spiropyrrolidone scaffolds containing three contiguous stereocenters with two spiroquaternary stereocenters in excellent yields (up to 99%) with high enantio- and diastereoselectivities (up to 99% ee and up to >20 : 1 dr). This method provides an economical and practical approach for the asymmetric synthesis of medicinally relevant molecules.

Squaramide-catalysed asymmetric cascade reactions of 2,3-dioxopyrrolidines with 3-chlorooxindoles.

A highly efficient method for the enantioselective construction of dispirocyclic compounds has been developed by the squaramide-catalysed asymmetric Michael addition/cyclization cascade reaction of 2,3-dioxopyrrolidines with 3-chlorooxindoles. The corresponding chiral dispiro[indoline-3,1'-cyclopropane-2',3''-pyrrolidine]-2,4'',5''-triones were obtained in high yields with excellent stereoselectivities (up to 94% yield, >25 : 1 dr and >99% ee). Furthermore, a gram-scale experiment confirmed the reliability of the current reaction and further effective transformation of the product has been realized.