Synthesis, characterization, and catalytic properties of new electrophilic iridium(III) complexes containing the (R)-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl ligand.
The oxidative addition of MeI to the Ir(I) square-planar complex IrI(CO)((R)-(+)-BINAP) where (R)-(+)-BINAP = (R)-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)) results in the formation of two diastereomers in a 2:1 ratio of the Ir(III) oxidative addition product IrI(2)(CO)(Me)((R)-(+)-BINAP) (4a and 4b) in a 85% overall yield. Upon iodide abstraction from the diastereomeric mixture with 2 equiv of AgSbF(6) in the presence of diethyl isopropylidene malonate (DIM), two diastereomers of the dicationic complex [Ir(CO)(Me)(DIM)((R)-(+)-BINAP)][SbF(6)](2) (5) are formed in a 90% yield with a ratio of 9:1. One diastereomer of the diiodide complex 4 and one diastereomer of the dicationic complex 5 have been characterized by X-ray diffraction. An anion exchange reaction of 5 with NaBAr(4)(f-) (BAr(4)(f-) = B(3,5-(CF(3))(2)C(6)H(3))(4)) affords [Ir(CO)(Me)(DIM)((R)-(+)-BINAP)][BAr(4)(f)](2) (6) in quantitative yield. Both 5 and 6 are active Lewis acid catalysts for the polarized Nazarov cyclization and the Diels-Alder reaction. In the Nazarov cyclization, when NaBAr(4)(f) is added as a cofactor for the reaction catalyzed by 5 or 6, the resultant oxyallyl cation intermediate from the 4pi conrotation undergoes a Wagner-Meerwein rearrangement to afford spirocyclic cyclopentenones in modest to good yields.
Atesin
Abdurrahman C
AC
Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Zhang
Jing
J
Vaidya
Tulaza
T
Brennessel
William W
WW
Frontier
Alison J
AJ
Eisenberg
Richard
R
D002384:Catalysis; D018360:Crystallography, X-Ray; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D008024:Ligands; D009942:Organometallic Compounds; D007495:Iridium