Highly diastereoselective preparation of chiral NHC-boranes stereogenic at the boron atom. Issue 26 (3rd June 2019)

• Record Type: Journal Article
• Authors: Aupic, Clara; Abdou Mohamed, Amel; Figliola, Carlotta; Nava, Paola; Tuccio, Béatrice; Chouraqui, Gaëlle; Parrain, Jean-Luc; Chuzel, Olivier
• Is Part Of: Chemical science. Volume 10:Issue 26(2019)
• Page Start: 6524
• Page End: 6530
• Publication Date: 2019-06-03
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9sc01454c
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Stereogenic main group elements, a promising strategy for metal-free enantioselective catalysis. Abstract : Stereogenic main group elements are clearly generating interest in the enantioselective catalysis field. Surprisingly, while chiral organoboron reagents are very useful in stereoselective transformations, few scaffolds stereogenic at boron and configurationally stable have been reported to date. Herein, we describe an original library of chiral NHC-boranes, stereogenic at the boron atom, that has been prepared in only a few steps and in good yields (up to 93%). Key steps involve a chlorination/arylation sequence in the presence of simple Grignard reagents from bicyclic NHC-boranes. The high and unprecedented diastereoselectivity observed during the second step (up to 99 : 1 dr) has been rationalized through a plausible SRN 1 mechanism thanks to EPR observations and DFT calculations.