engleski

Biomimetic Rearrgament of the 2-cyclopentyl-2-propyl Cation

In order to investigate the mechanism of the five membered ring enlargement in carbocation intermediates in steroid biosynthesis, the rearrangement processes in the model carbocation, the 2-cyclopentyl-2-propyl cation 5, were followed by means of ^1H and ^13C NMR spectroscopy. Carbocations 5A and 5B were prepared in SbF_5 / SO_2ClF / SO_2F_2 from the corresponding alcohol precursors. At about -100 °C a ring enlargement process takes place to give the 1,2-dimethylcyclohexyl cation 7. Quantum chemical calculations of model carbocation structures 5A, 5B, 6 and 7 were carried out at HF/6-31G(d) and B3LYP/6-31G(d) levels of theory.

carbocations; rearrangement; ring expansion; NMR spectroscopy; quantum-chemical DFT calculations

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