Over the past several years, our research group has developed a new rhodium-catalyzed methylenation reaction of carbonyl derivatives for the synthesis of terminal alkenes. The Wilkinson's complex (RhCl(PPh₃)₃) displayed the best catalytic activity for the methylenation reaction. In addition, this catalyst is well known to catalyze several other reactions with alkenes such as hydroboration and hydrogenation reaction, thus opening up the possibility of performing various cascade processes. We wish now to report a rhodium-catalyzed methylenation-hydroboration cascade process which lead to the formation of the corresponding organoborane product. The oxidation of this organoborane intermediate produced the corresponding alcohol where a second homologation reaction using trimethylsilyldiazomethane or LiCH₂Cl followed by an oxidative work-up provide to the corresponding carboxylic acid. The boronate intermediate is also a precursor for Suzuki coupling reaction, thus a one-pot process using a palladium catalyst could be also envisioned.