Conformation design of hydrocarbon backbones: A modular approach

A modular approach towards a conformation design of hydrocarbon backbones is described. The idea is to attach substituents (e.g., methyl branches) to a hydrocarbon backbone in such a manner that they create destabilizing syn-pentane interactions in all but one diamond-lattice backbone conformation. This creates a substantial (> 7 kJ mol^-1) energy gap between the lowest energy conformer and the higher energy conformers. In consequence, the lowest energy conformer will be populated to a high extent (e.g., > 80%). Small hydrocarbon modules that fulfil this requirement have been identified in a systematic manner, highlighting the role of inductor groups to control the conformation at neighboring skeletal bonds. These modules can in turn serve as inductor groups for more extended hydrocarbon chains, or they may be combined with one another to form larger monoconformational hydrocarbon structures.