Tungsten-anisole complex provides 3,6-substituted cyclohexenes for highly diversified chemical libraries
Justin T. Weatherford-Pratt, Jeremy M. Bloch, Jacob A. Smith, Megan N. Ericson, Daniel J. Siela, Mason R. Ortiz, Mary H. Shingler, Sarah Fong, Jonathan Laredo, Ishaan U. Patel, Matt McGraw, Diane A. Dickie, W. Dean Harman
Abstract
Medicinal chemists use vast combinatorial molecular libraries to develop leads for new pharmaceuticals. The syntheses of these compounds typically rely on coupling molecular fragments through atoms with planar (sp 2 ) geometry. These so-called flat molecules often lack the protein binding site specificity needed to be an effective drug. Here, we demonstrate a coupling strategy in which a cyclohexene is used as a linker to connect two diverse molecular fragments while forming two new tetrahedral (sp 3 ) stereocenters. These connections are made with the aid of a tungsten complex that activates anisole toward an unusual double protonation, followed by sequential nucleophilic additions. As a result, either cis- or trans-disubstituted cyclohexenes can be prepared with a range of chemical diversity unparalleled by other dearomatization methods.