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Streocontrolled construction of six vicinal stereogenic centers on spiropyrazolones via organocascade Michael/Michael/1,2-addition reactions.

ABSTRACT: A highly stereoselective one-pot procedure for the synthesis of spiropyrazolone derivatives bearing six contiguous stereogenic centers including two tetrasubstituted carbons has been developed. Under sequential catalysis by two organocatalysts, a cinchona-derived aminosquaramide and DBU, a series of diversely functionalized spiropyrazolones are obtained in good yields (47-62%) and excellent stereoselectivities (up to >25:1 dr and 98-99% ee). The opposite enantiomers of the spiropyrazolones are also accessible by employing a pseudoenantiomeric aminosquaramide catalyst.

SUBMITTER: Chauhan P

PROVIDER: S-EPMC4699267 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

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Streocontrolled construction of six vicinal stereogenic centers on spiropyrazolones via organocascade Michael/Michael/1,2-addition reactions.

Chauhan Pankaj P Mahajan Suruchi S Loh Charles C J CC Raabe Gerhard G Enders Dieter D

Organic letters 20140519 11

A highly stereoselective one-pot procedure for the synthesis of spiropyrazolone derivatives bearing six contiguous stereogenic centers including two tetrasubstituted carbons has been developed. Under sequential catalysis by two organocatalysts, a cinchona-derived aminosquaramide and DBU, a series of diversely functionalized spiropyrazolones are obtained in good yields (47-62%) and excellent stereoselectivities (up to >25:1 dr and 98-99% ee). The opposite enantiomers of the spiropyrazolones are a ...[more]

PMID: 24840166

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