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2.4.6.2 Variation 2: Via Benzylic Cations

DOI: 10.1055/sos-SD-002-00214

Kündig, E. P.; Pache, S. H.Science of Synthesis, (20032176.

Benzylic carbocations complexed to tricarbonylchromium are stabilized by delocalization of the positive charge onto the chromium. Benzylic leaving groups that can adopt a conformation antiperiplanar to the arenechromium bond undergo facile cleavage. Rotation about the CArCα bond is restricted in the cation. Nucleophilic substitution therefore occurs with retention of configuration.[‌114‌] Analysis using density functional theory supports the stabilization and the rotational barrier in the cationic intermediates.[‌137‌,‌163‌]

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References


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