Bifunctional iminophosphorane catalysed enantioselective sulfa-Michael addition of alkyl thiols to alkenyl benzimidazoles

Michele Formica; Geoffroy Sorin; Alistair J M Farley; Jesús Díaz; Robert S Paton; Darren J Dixon

doi:10.1039/c8sc01804a

Bifunctional iminophosphorane catalysed enantioselective sulfa-Michael addition of alkyl thiols to alkenyl benzimidazoles

Chem Sci. 2018 Jul 23;9(34):6969-6974. doi: 10.1039/c8sc01804a. eCollection 2018 Sep 14.

Authors

Michele Formica¹, Geoffroy Sorin^{1

2}, Alistair J M Farley¹, Jesús Díaz³, Robert S Paton⁴, Darren J Dixon¹

Affiliations

¹ Department of Chemistry , Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , UK . Email: darren.dixon@chem.ox.ac.uk.
² Faculté des Sciences Pharmaceutiques et Biologiques , Unité CNRS UMR 8638 COMETE , Paris Descartes University , Sorbonne Paris Cité , 4 Avenue de l'Observatoire , 75270 Paris Cedex 06 , France.
³ Departamento de Química Orgánica , Universidad de Extremadura , Avda. Universidad , s/n, 10003 Cáceres , Spain.
⁴ Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , USA.

Abstract

The first enantioselective sulfa-Michael addition of alkyl thiols to alkenyl benzimidazoles, enabled by a bifunctional iminophosphorane (BIMP) organocatalyst, is described. The iminophosphorane moiety of the catalyst provides the required basicity to deprotonate the thiol nucleophile while the chiral scaffold and H-bond donor control facial selectivity. The reaction is broad in scope with respect to the thiol and benzimidazole reaction partners with the reaction proceeding in up to 98% yield and 96 : 4 er.