Phosphophosphidites Derived from BINOL

Phosphophosphidites of the type R2P–P(binol) [where binol = the dianion of (S)‐1,1′‐bi‐2‐naphthol] are the phosphorus analogues of the ubiquitous phosphoramidites, R2N–P(binol) and are readily accessed by the chlorosilane elimination reaction between R2P–SiMe3 and Cl–P(binol). The crystal structure of iPr2P–P(binol) (1) has been determined and shows a P–P bond length in the normal range. The solution reactions of 1 have been investigated, principally by 31P NMR spectroscopy which has revealed that: (a) in contrast to the phosphoramidites, 1 is extremely moisture sensitive; (b) the P–P bond in 1 is cleaved upon reaction with H2O, MeOH or mesitol; (c) the P–O bonds in 1 are cleaved upon reaction with pyrrolidine; (d) the integrity of 1 is retained upon coordination to BH3 or Mo0. The crystal structure of cis‐[Mo(CO)4(1)2] shows that 1 is bound to the Mo at the P(binol) site and the νCO of 2032 cm‐1 indicates that 1 has similar ligand properties to a phosphonite. The high reactivity of phosphophosphidite 1 contrasts with the inertness of its N‐analogue, phosphoramidite A. The P–P bond in 1 is readily cleaved by water or methanol but remains intact in the Lewis adducts of 1 with BH3 and in the complex [Mo(CO)4(1)2].