BINAP reductive coupling with

An amine can be coupled with an aryl bromide, iodide or triflate in the presence of a palladium catalyst, a base, typically KOBu or CSCO3, and a ligand such as the bidentate phosphine BINAP. These reactions are known as Buchwald or Buchwald-Hartwig reactions (Scheme 10.24). A catalytic cycle is again involved, with the amine displacing X from Ar-Pd -X to form Ar-Pd -NHR2. Abstraction of a proton by the base produces Ar-Pd -NRj, which undergoes a reductive elimination. 

Pu and co-workers incorporated atropisomeric binaphthols in polymer matrixes constituted of binaphthyl units, the macromolecular chiral ligands obtained being successfully used in numerous enantioselective metal-catalyzed reactions,97-99 such as asymmetric addition of dialkylzinc reagents to aldehydes.99 Recently, they also synthesized a stereoregular polymeric BINAP ligand by a Suzuki coupling of the (R)-BINAP oxide, followed by a reduction with trichlorosilane (Figure 10).100... 

The coupling of primary amines with resin-bound aryl bromides was effected cleanly with both the ( )-BINAP/Pd- and DPPF/Pd-catalyst systems. Groups at Boehringer-Ingelheim and Merck have reported that BINAP/Pd-and DPPF/Pd-based protocols allow for efficient C-N bond formation, while use of (o-toOjP/Pd-catalysis results in significant aryl bromide reduction, Eq. (71) [31,32]. 

BusP as ligand.Poor yields in the reductive cyclization method—when competitive cyclization is possible—and also the need for milder reaction conditions in the cyclization step urged Emoto et al. to report an alternative method based on sequential palladium-catalyzed aryl amination (Scheme 10). The substrate for the cyclization was 2-amino-2 -bromo-diphenylamine, obtained by selective bromination and reduction of the well-known 2-nitrodiphenyl-amines or by coupling of 2-bromoaniline with a l-bromo-2-nitrobenzene and subsequent reduction. Treatment of 2-bromo-2 -nitrodiphenylamine with catalytic amounts of palladium(II) and BINAP as ligand afforded the desired phenazines in good yields. ... 

The bicychc structure 7 is desymmetrized by reductive C-O bond splitting in the presence of the Ni complex of (5)-BINAP and diisobutylalumium hydride (DIBAL-H). This couple ensures enantioselective hydrometalation-elimination from one of the enantiotopic carbon atoms in the bridge to the C-O bond, affording dihydronaphthalenol (f )-8 in 88% yield and 98% e.e. In the following steps, protection of 8 as the sUyl ether 9 was completed before addition of bromine to the double bond in the presence of triethylamine. This intermediate was treated with DBU 1,8-diazabicyclo[5,4,0]undec-7-ene, strong, crowded base) without isolation, and on regioselective elimination of hydrogen bromide, vinylbromide 10 was isolated in 83% yield. 

---