trans-1,4-Diphosphacyclohexanes were successfully synthesized by the stereospecific intramolecular coupling reaction of the optically active
bisphosphine. This is a new route for the construction of the trans-1,4-diphosphacyclohexane skeleton. A cis isomer was also prepared along
with the trans isomer from a mixture of rac- and meso-bisphosphines. The coordinated boranes were easily removed to afford the corresponding
1,4-diphosphacyclohexanes.