Ultrasound-promoted palladium-catalyzed carbonyl allylation by allylic alcohols with tin(II) chloride in non-polar solvents

Heterogeneous ultrasound-promoted palladium-catalyzed carbonyl allylation by γ-substituted allylic alcohols with tin(II) chloride in non-polar solvents such as diethyl ether, diisopropyl ether and toluene was carried out stepwise (first, the formation of allylic tin intermediates by ultrasonication, followed by the allylation of aldehydes by the intermediates) to produce 1,4-disubstituted 3-buten-1-ols regioselectively in moderate yields. The regioselectivity (-selection) in the ultrasound-promoted reaction is the inverse of that (γ-selection) in the homogeneous palladiumcatalyzed carbonyl allylation in polar solvents such as 1,3-dimethyl-2-imidazolidinone, DMF, DMSO and ethylene glycol. The more bulky the γ-substituent, the higher is the -regioselectivity.     

Use of Mucor miehei lipase in the preparation of long chain 3-O-acylcatechins

Long chain 3-O-acylcatechins were prepared in high yield by alcoholysis with n-butanol of the corresponding pentaacylderivatives in the presence of lipase from Mucor miehei (immobilised, Lipozyme® IM). In an alternative procedure, the mixed ester, tetraacetyl-3-O-acylcatechin, was synthesised and used as substrate for the same alcoholysis process that proceeds with higher reaction rate. The obtained 3-O-acyl derivatives are more lipophilic than the parent catechin and thus suitable for a possible application of their antioxidative properties in hydrophobic matrices.