Diversity Oriented Approach to New Tetrahedral Building Blocks by Ring‐Closing Metathesis

Abstract

AbstractWe disclose an approach to a library of novel multidimensional O‐heterocycles based on a rigid, tetrahedral core. New derivatives of tetraphenylmethane (TPM) have been synthesized by employing Claisen rearrangement (CR) and ring‐closing metathesis (RCM) as key steps. Mono‐, di‐, tri‐, and tetra‐substituted benzofurans, 2H‐chromenes, and benzoxepine derivatives are reported. Various heterocyclic cores present in these compounds are key structural elements present in several natural products and pharmaceuticals as well as valuable precursors for the construction of complex molecules with the tetrahedral framework. To the best of our knowledge, this is the first report involving the synthesis of five‐, six‐, and seven‐membered O‐heterocycles in TPM core and the basecatalyzed inexpensive synthesis of several isomerized intermediates that are useful to prepare oxacycles such as benzofuran and 2H‐chromenes. The symmetrical and unsymmetrical one, two, three, and four‐armed architecture of TPM makes it a valuable starting point for building complex molecular and supramolecular architectures. To expand the unmet chemical space of the TPM core, we have prepared twenty new derivatives by a unified approach. Additionally, we report a simple, catalyst‐free, and inexpensive recipe for double bond isomerization based on KOtBu to assemble various oxacycles derived from different trityl chloride derivatives.