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Generation and Reactivity of {(Ethane‐1,2‐diyl)bis[diisopropylphosphine‐ κP ]}‐{[2,4,6‐tri( tert ‐butyl)phenyl]phosphino‐ κP }rhodium ([Rh{PH( t Bu 3 C 6 H 2 )}( i Pr 2 PCH 2 CH 2 P i Pr 2 )]): Catalytic C−P Bond Formation via Intramolecular C−H/P−H Dehydrogenative Cross‐Coupling
Author(s) -
Stradiotto Mark,
Fujdala Kyle L.,
Don Tilley T.
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20011017)84:10<2958::aid-hlca2958>3.0.co;2-l
Subject(s) - chemistry , rhodium , intramolecular force , medicinal chemistry , catalysis , ligand (biochemistry) , toluene , reactivity (psychology) , thermal decomposition , oxidative addition , stereochemistry , organic chemistry , receptor , medicine , alternative medicine , pathology , biochemistry
The complex [Rh( η 3 ‐benzyl)(dippe)] ( 1 ; dippe=bis(diisopropylphosphino)ethane=(ethane‐1,2‐diyl)bis[diisopropylphosphine]) reacted cleanly with Mes*PH 2 ( 2 ; Mes*=2,4,6‐ t Bu 3 C 6 H 2 ) to provide a new Rh species [Rh(H)(dippe)(L)] ( 3 ), L being the 2,3‐dihydro‐3,3‐dimethyl‐1 H ‐phosphindole ligand 4 (= t Bu 2 C 6 H 2 (CMe 2 CH 2 PH)) ( Scheme 1 ). Complex 3 was converted to the corresponding chloride [Rh(Cl)(dippe)(L)] ( 6 ) when treated with CH 2 Cl 2 , whereas the dimeric species [Rh 2 { μ ‐ t Bu 2 C 6 H 2 (CMe 2 CH 2 P)}( μ ‐H)(dippe) 2 ] ( 7 ) was formed upon thermolysis in toluene ( Scheme 2 ). The structures of 6 and 7 ⋅C 7 H 8 were determined by X‐ray crystallography. Complexes 1 and 3 served as catalyst precursors for the dehydrogenative coupling of C−H and P−H bonds in the conversion of 2 to 4 ( Scheme 3 ). Deuteration studies with Mes*PD 2 exposed a complex series of bond‐activation pathways that appear to involve C−H activation of the dippe ligand by the Rh‐atom ( Schemes 4 and 5 )