Computer molecular model, configuration

To establish the relative configuration of the newly formed stereocenters of the bridged 1,2-oxazocine 109, obtained from an alkene-aldehyde intermediate, a computer-assisted molecular modeling coupled with I/hh calculations was utilized. 

With any type of molecular modeling, there is generally a tradeoff between cost and reliability, and one typically shuns models that cost more without increasing reliability. In practice, this cost is usually expressed as computational effort, or computer time. In gas phase modeling, one typically finds molecular mechanics and semiempirical molecular orbital theory at the low-cost end and multireference configuration interaction or coupled-cluster theory at the other, with the choice dictated by the size of the system. System size also influences the choice of solvation model. We consider first the least expensive models, those that take no account of the quantum mechanical nature of the solute. 

In all these studies, the current availability of computer-based molecular modeling programs (available from Tripos, Biosym Technologies, and Molecular Simulations) facilitate the exploration of optimal molecular configurations before actually attempting to synthesize compounds of interest. 

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