Enantioselective bifunctional iminophosphorane catalyzed sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters† †Electronic supplementary information (ESI) available: Experimental procedures, spectroscopic data, copies of 1H and 13C NMR spectra and HPLC and GC chromatograms. See DOI: 10.1039/c6sc02878k Click here for additional data file

• Published in: Chemical science (Cambridge) Vol. 8; no. 1; pp. 606 - 610
• Main Authors: Yang, Jinchao, Farley, Alistair J. M., Dixon, Darren J.
• Format: Journal Article
• Language: English
• Published: Royal Society of Chemistry 14.09.2016
• Subjects: Chemistry
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c6sc02878k

The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) organocatalyst is described. The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) organocatalyst is described. The low acidity of the alkyl thiol pro-nucleophiles is overcome by the high Brønsted basicity of the catalyst and the chiral scaffold/thiourea hydrogen-bond donor moiety provides the required enantiofacial discrimination in the addition step. The reaction is broad in scope with respect to the alkyl thiol and β-substituent of the α,β-unsaturated ester, affords sulfa-Michael adducts in excellent yields (up to >99%) and enantioselectivity (up to 97 : 3 er) and can operate down to 1 mol% catalyst loading.