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An asymmetric approach toward chiral multicyclic spirooxindoles from isothiocyanato oxindoles and unsaturated pyrazolones by a chiral tertiary amine thiourea catalyst.

Chemical communications (Cambridge, England) (2013-01-22)
Qiao Chen, Jinyan Liang, Shoulei Wang, Dong Wang, Rui Wang
ABSTRACT

The first organocatalytic Michael-cyclization cascade reaction between isothiocyanato oxindoles and unsaturated pyrazolones has been developed. The multicyclic spiro[oxindole/thiobutyrolactam/pyrazolone] core structures containing three contiguous stereogenic centers, including two spiro quaternary centers, were prepared with excellent diastereo- (up to >20 : 1) and enantioselectivities (up to 99% ee).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Thiourea, ACS reagent, ≥99.0%
Sigma-Aldrich
Thiourea, ReagentPlus®, ≥99.0%