Stereoselective [4+2]-Cycloaddition with Chiral Alkenylboranes

Dongshun Ni; Brittany P Witherspoon; Hong Zhang; Chen Zhou; K N Houk; M Kevin Brown

doi:10.1002/anie.202000652

Stereoselective [4+2]-Cycloaddition with Chiral Alkenylboranes

Angew Chem Int Ed Engl. 2020 Jul 6;59(28):11432-11439. doi: 10.1002/anie.202000652. Epub 2020 May 11.

Authors

Dongshun Ni¹, Brittany P Witherspoon², Hong Zhang^{3

4}, Chen Zhou¹, K N Houk³, M Kevin Brown¹

Affiliations

¹ Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47401, USA.
² Current Address: Janssen Research & Development, LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA.
³ Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.
⁴ Current Address: College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.

PMID: 32390259
DOI: 10.1002/anie.202000652

Abstract

A method for the stereoselective [4+2]-cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N-protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations of the C-B bond such as oxidation and homologation. Detailed computation evaluation of the reaction has uncovered a surprising role of the counterion on stereoselectivity.

Keywords: alkenylboranes; chiral auxiliaries; cycloaddition; dienes; synthetic methods.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.