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Highly diastereoselective preparation of chiral NHC-boranes stereogenic at the boron atom.

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 S_RN1 mechanism thanks to EPR observations and DFT calculations.

SUBMITTER: Aupic C

PROVIDER: S-EPMC6611065 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Highly diastereoselective preparation of chiral NHC-boranes stereogenic at the boron atom.

Aupic Clara C Abdou Mohamed Amel A Figliola Carlotta C Nava Paola P Tuccio Béatrice B Chouraqui Gaëlle G Parrain Jean-Luc JL Chuzel Olivier O

Chemical science 20190524 26

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/a ...[more]

PMID: 31341605

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