Stereoselective Synthesis of ortho-Carbaborane-Containing P-Chiral Phosphanylferrocenes

Abstract

Diastereomerically pure 1-[1-(1,2-dicarba-closo-dodecaboran(12)yl)chlorophosphanyl]-2-N,N-dimethylaminomethylferrocene ((R P ,S Fc /S P ,R Fc )-3) and enantiomerically pure 12)yl)}chlorophosphanyl]ferrocenyl}ethylamine ((S C ,S P ,R Fc )-4) were prepared by reaction of monolithiated 1,2-dicarba-closo-dodecaborane( 12) and the corresponding racemic or enantiomerically pure aminoalkylferrocenyldichlorophosphanes (1 or (S,R)-2). Two equivalents of 1 also reacted with dilithiated 1,2-dicarba-closo-dodecaborane(12) to yield stereoselectively the R

Chiral Rhodium(I) Complexes of 1,2‐Bis‐(chloroalkoxyphosphanyl)‐ and 1,2‐Bis‐(amidoalkoxyphosphanyl)‐1,2‐dicarba‐closo‐dodecaboranes(12)

“…Similar behaviour was previously observed for a monosubstituted secondary carboranyl ferrocenylphosphane, wherein two bulky substituents at the phosphorus atom underwent epimerisation. In this case it could be shown that the substitution of the hydrogen atom by a methoxy group suppresses the epimerisation reaction completely …”

Planar‐Chiral Secondary Ferrocenylphosphanes

“…The only other derivative, with ortho ‐carborane instead of t Bu, was previously reported by us. [11a] Although the CH 2 –NMe 2 and P(H)–C(CH 3 ) 3 substituents in 1 are found to be slightly disordered, the accuracy of the structure parameters is more than acceptable. The P1–C1 [180.6(3) pm] and P1–C14 [187.1(5) pm] bond lengths in 1 are comparable to those of the carborane derivative [P1–C1 181.0(3) pm and P1–C14 187.6(3) pm].…”

“…The P1–C1 [180.6(3) pm] and P1–C14 [187.1(5) pm] bond lengths in 1 are comparable to those of the carborane derivative [P1–C1 181.0(3) pm and P1–C14 187.6(3) pm]. [11a]…”

“…Bulb‐to‐bulb distillation under high vacuum (10 –6 mbar, 80 °C)[11b] was attempted for purification of 3 and 4 . This technique was, however, not at all useful, as it is time‐consuming, and the products started to decompose upon longer heating.…”

“…Borane–phosphane adducts are commonly used for protection of reactive phosphanes , . Furthermore, primary phosphane–borane adducts have received attention as precursors for inorganic polymers, for example, poly(phosphinoborane)s obtained by catalytic dehydrocoupling, and low‐molecular‐weight phosphinoborane polymers could be obtained from secondary phosphane–borane adducts by thermolysis.…”