Pinacol rearrangement diastereoselectivity

An alternative approach to the bicyclic enediyne core of esperamicin utilizing an intramolecular Diels-Alder reaction was reported by Schreiber and co-workers (Scheme 7-45) [195-197]. This approach was initially hampered by an unfavorable regiochemical outcome in the Diels-Alder reaction (195 - 196), but was successfully corrected by a clever maneuver involving a Tsuchihashi pinacol rearrangement [198, 199] with concomitant diastereoselective acyloin shift to secure the desired bicyclic ring skeleton (197 - 198 - 199). 

Alvarez-Manzaneda E, Chahboun R, Barranco I, Cabrera E, Alvarez E, Lara A, Alvarez-Manzaneda R, Hmamouchi M, Es-Samti H. Diastereoselective routes towards the austrodor-ane skeleton based on pinacol rearrangement synthesis of (+)-austrodoral and (+)-austrodoric acid. Tetrahedron 2007 63 11943-11951. 

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