A novel ring enlargement methodology and its application to taxane A,B
-ring synthesis is introduced In a one pot-procedure an elimination-ep
oxidation sequence starting from 5 leads to molecules of type 6 which
can be transformed into tarane A,B-ring systems via a tandem reaction.
A retroaldol-epoxidation sequence starting from 15 yields taxane A,B-
ring systems suitably functionalized for Diels-Alder reactions.