Synthesis and unique reversible splitting of 14-membered cyclic aminomethylphosphines on to 7-membered heterocycles

A novel type of 14-membered cyclic polyphosphine, namely 1,8-diaza-3,6,10,13-tetraphosphacyclotetra-decanes 2(a)-4(a) has been synthesized by the condensation of 1,2-bis(phenylphosphino) ethane, formaldehyde and alkylamines (isopropylamine, ethylamine and cyclohexylamine) as a RRRR/SSSSstereoisomer. The structure of macrocycle 2(a) was investigated by NMR-spectroscopy and X-ray crystal structure analysis. The unique reversible processes of macrocycles 2(a)-4(a) splitting onto the corresponding rac-(2(b)-4(b)) and meso-(2(c)-4(c)) stereoisomers of 1-aza-3,6-diphosphacycloheptanes were discovered.