Site-selective Csp3-H aryloxylation of natural product Tanshinone IIA and its analogues

A novel catalyst-free Csp³-H aryloxylation approach allowing for rapid installation of a wide range of aryloxyl groups regioselectively at the C-4 position of Tanshinone IIA under simple and mild conditions was developed. This unique protocol exhibited atom-/step-economy, low cost, high efficiency and robust functional-group tolerance, which will greatly facilitate to diversify the A-ring of the bioactive natural product.     

Enantioselective organocatalytic aryloxylation of aldehydes with o-quinones

An enantioselective organocatalytic inverse electron demand hetero Diels-Alder reaction of in situ generated enamines with o-quinone reagents is reported. The method, which is optimal in wet acetonitrile at ambient temperature, provides a new and direct asymmetric route to the aryl alkyl ether motif and an alternative metal-free strategy to S_N2 substitutions with phenolate nucleophiles.