Expanding the Hydrocarbon Landscape: Stereoselective Synthesis of Functionalized ttt -[13]Graphanes

Abstract

Despite the significant interest in rigid, sp3-rich 3D hydrocarbon frameworks in medicinal and materials chemistry, the [13]graphanyl scaffold has remained synthetically prohibitive and, consequently, underexplored. Herein, we report a scalable, de novo stereoselective synthesis of the ttt-[13]graphanyl architecture utilizing a key dienyne metathesis cascade. To overcome the profound steric shielding at the central carbon vertex, we harnessed radical-mediated photocatalytic decarboxylation to install diverse functional groups, generating a library of centrally derivatized ttt-[13]G analogues. Complementary peripheral functionalization was also achieved via site-selective MHAT chemistry. Density functional theory (DFT) calculations rationalized the empirical reactivity trends, mapping the competitive landscape between Giese additions and hydrogen-atom transfer quenching. Finally, X-ray crystallographic analyses confirmed a substituent-dependent “doming” distortion of the rigid tricyclic framework. Together, these results provide a synthetic foundation to incorporate the [13]graphane architecture into advanced functional molecules, offering a new 3D node for rational molecular design.