aldehydes 10 under benzoic acid catalysis. C–C coupling reaction and Wittig olefination can also be performed in a one-step procedure. Preliminary experiments have been performed to carry out the synthesis on a solid support. Applications to the chain elongation and functionalisation of the chain terminus in a C-7 substituted estra-1,3,5(10)-triene 14 and a C-16 substituted estra-1,3,5(10),6-tetraene