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

摘要

The design of stereodivergent transformations is of great interest to the synthetic community as it allows to funnel 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 parameterization 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 Cp^X ligand on rhodium.