Synthesis of Trioxatricornan and Derivatives. Useful Keystones for the Construction of Rigid Molecular Cavities

Abstract

The synthesis of a new class of organic keystones for the development of macrocage structures is presented. These represent some of the most versatile building blocks for macrocage construction. The keystone structure developed herein can be interpreted as either a centrally alkylated [cd,mn]dibenzopyrene or a tris ortho-bridged triphenylmethane. We call this basic skeleton tricornan. Routes into both chiral (C3 and C1 symmetry) and achiral (C3v symmetry) derivatives are reported. The synthesis of derivatives of the trioxatricornan keystone, leading to two macrocage structures, is presented. The X-ray structures of cent-methyltrioxatricornan 7 and 2,6,10-tris(dimethylamino)-cent-methyltrioxatricornan (20) are discussed and compared to that of 1,1,1-triphenylethane. Empirical force field and AM1 calculations are compared to the X-ray structures and discussed. A general discussion on the keystone analogy is presented. © 1992, American Chemical Society. All rights reserved.