Stereodivergent Rhodium(III)-Catalyzed cis-Cyclopropanation Enabled by Multivariate Optimization

J Am Chem Soc. 2018 Aug 1;140(30):9587-9593. doi: 10.1021/jacs.8b04243. Epub 2018 Jul 23.

Abstract

The design of stereodivergent transformations is of great interest to the synthetic community as it allows funneling of a given reaction pathway toward one stereochemical outcome or another by only minor adjustments of the reaction setup. Herein, we present a physical organic approach to invert the sense of induction in diastereoselective cyclopropanation of alkenes with N-enoxyphthalimides through rhodium(III) catalysis. Careful parametrization of catalyst-substrate molecular determinants allowed us to interrogate linear-free energy relationships and establish an intuitive and robust statistical model that correlates an extensive number of data points in high accuracy. Our multivariate correlations-steered mechanistic investigation culminated with a robust and general diastereodivergent cyclopropanation tool where the switch from trans- to cis-diastereoinduction is attributed to a mechanistic dichotomy. Selectivity might be determined by the flexibility of rhodacyclic intermediates derived from ring-opened versus -unopened phthalimides, induced by both their respective ring size and the Sterimol B1 parameter of the CpX ligand on rhodium.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alkenes / chemistry*
  • Catalysis
  • Cyclization
  • Cyclopropanes / chemical synthesis*
  • Models, Chemical
  • Phthalimides / chemistry*
  • Rhodium / chemistry*
  • Stereoisomerism

Substances

  • Alkenes
  • Cyclopropanes
  • Phthalimides
  • Rhodium