New taxanes from the seeds of Taxus mairei.

Two new taxoid metabolites were isolated from the methanol extract of the Taxus mairei seeds. Their structures were established as 2alpha-hydroxy-9alpha,10beta,13alpha-triacetoxy-5alpha-cinnamoyloxytaxa-11-en-4beta,20-epoxide (1) and 2'-acetyl taxol (2) on the basis of spectral analysis.

Steric acceleration of an uncatalysed ene reaction at room temperature.

The bulky trityl steric buttress is used to effect an intramolecular, uncatalysed ene reaction that operates at room temperature, whilst smaller buttresses require heat.