Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol?

Organic & Biomolecular Chemistry Pub Date: 2011-09-22 DOI: 10.1039/C1OB06121F

Abstract

One-point binding chiral ruthenium Lewis acids incorporating the C2-symmetric electron-poor bidentate phosphinite ligand BIPHOP-F and a Cp or an indenyl ‘roof’ can efficiently catalyze asymmetric intramolecular Diels–Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a total synthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation.

Graphical abstract: Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol
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