Enantioselective copper catalysed C-H insertion reaction of 2-sulfonyl-2-diazoacetamides to form γ-lactams

Org Biomol Chem. 2014 Oct 14;12(38):7612-28. doi: 10.1039/c4ob01430h.

Abstract

The first examples of asymmetric copper-catalysed intramolecular C-H insertion reactions of 2-sulfonyl-2-diazoacetamides are described; trans γ-lactams with up to 82% ee are achieved with the CuCl2-bisoxazoline-NaBARF catalyst system. The reactions generally display high efficiency and high trans selectivity, and also a strong regiochemical preference for insertion to lead to the formation of 5-membered rings over 4-membered rings. In cases where there are competing C-H insertion pathways available, to form sulfolanes or thiopyrans, only the insertion into the amide chain to form γ-lactams is observed. With phenylsulfonyl derivatives, a minor competing C-H insertion pathway leading to β-lactams is seen; interestingly, changing the identity of the copper ligand changes the product ratio of β/γ-lactams. The copper catalysed reactions compare favorably in terms of efficiency and enantioselectivity to the corresponding reactions catalysed by commercially available chiral rhodium catalysts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon / chemistry*
  • Catalysis
  • Copper / chemistry*
  • Diazonium Compounds / chemistry*
  • Hydrogen / chemistry*
  • Lactams / chemistry*
  • Stereoisomerism
  • Substrate Specificity

Substances

  • Diazonium Compounds
  • Lactams
  • diazoacetamide
  • Carbon
  • Copper
  • Hydrogen