17 research outputs found
Use of ring-expanded diamino- and diamidocarbene ligands in copper catalyzed azide-alkyne "click" reactions
The
two-coordinate ring-expanded N-heterocyclic carbene copperÂ(I)
complexes [CuÂ(RE-NHC)<sub>2</sub>]<sup>+</sup> (RE-NHC = 6-Mes, 7-<i>o</i>-Tol, 7-Mes) have been prepared and shown to be effective
catalysts under neat conditions for the 1,3-dipolar cycloaddition
of alkynes and azides. In contrast, the cationic diamidocarbene analogue
[CuÂ(6-MesDAC)<sub>2</sub>]<sup>+</sup> and the neutral species [(6-MesDAC)ÂCuCl]<sub>2</sub> and [(6-MesDAC)<sub>2</sub>(CuCl)<sub>3</sub>] show good
activity when the catalysis is performed on water
Expanded ring diaminocarbene palladium complexes: synthesis, structure, and SuzukiâMiyaura cross-coupling of heteroaryl chlorides in water
Efficient Synthesis of 3-Arylphthalides using Palladium-Catalyzed Arylation of Aldehydes with Organoboronic Acids
First examples of diazepanylidene carbenes and their late-transition-metal complexes
The synthesis of the novel seven-membered N-heterocyclic carbene (NHC) 1,3-dicyclohexyl-1,3-diazepan-2-ylidene (3) and its 5,6-dioxolane derivative 4 is reported and their coordination chemistry with Rh(I), Ir(I), and Pt(0) discussed. The M(cod)(3)Cl, where M = Rh and Ir, complexes display a high rotation barrier at room temperature about the M-CNHC bond, whereas for the M(CO)2(3)Cl and Pt(nbe)2(3) complexes rapid rotation of the carbene ligand is observed at ambient temperature. The infrared (CO) values of the Rh(I) and Ir(I) derivatives M(CO)2(3)Cl give a measure of the donor ability of the new carbene ligands. The crystal structures of the amidinium salts 3·HPF6 and 4·HPF6 together with those of M(cod)(3)Cl [M = Rh, Ir], Ir(cod)(4)Br, Ir(CO)2(3)Cl, and Pt(nbe)2(3) are reported. Both the salts and the coordinated carbene ligands exhibit extremely large NCN angles; for the complexes the angles are in the range 115.5(3) [Pt(3)] to 122(11) [Ir(4)]
Sterically Hindered Benzophenones via Rhodium-Catalyzed Oxidative Arylation of Aldehydes
Preparation of Butadienylpyridines by IridiumâNHCâCatalyzed Alkyne Hydroalkenylation and Quinolizine Rearrangement
Iridium(I) Nâheterocyclic carbene complexes of formula Ir(Îș(2) O,OââBHetA)(IPr)(η (2)âcoe) [BHetA=bisâheteroatomic acidato, acetylacetonate or acetate; IPr=1,3âbis(2,6âdiisopropylphenyl)imidazolinâ2âcarbene; coe=cyclooctene] have been prepared by treating Ir(Îș(2) O,OââBHetA)(η (2)âcoe)(2) complexes with IPr. These complexes react with 2âvinylpyridine to afford the hydridoâiridium(III)âalkenyl cyclometalated derivatives IrH(Îș(2) O,OââBHetA)(Îș(2) N,CâC(7)H(6)N)(IPr) through the iridium(I) intermediate Ir(Îș(2) O,OââBHetA)(IPr)(η (2)âC(7)H(7)N). The cyclometalated IrH(Îș(2) O,Oââacac)(Îș(2) N,CâC(7)H(6)N)(IPr) complex efficiently catalyzes the hydroalkenylation of aromatic and aliphatic terminal alkynes and enynes with 2âvinylpyridine to afford 2â(4Râbutadienyl)pyridines with Z,E configuration as the major reaction products (yield up to 89â%). In addition, unprecedented (Z)â2âbutadienylâ5Râpyridine derivatives have been obtained as minor reaction products (yield up to 21â%) from the elusive 1Z,3gemâbutadienyl hydroalkenylation products. These compounds undergo a thermal 6Ïâelectrocyclization to afford bicyclic 4Hâquinolizine derivatives that, under catalytic reaction conditions, tautomerize to 6Hâquinolizine to afford the (Z)â2â(butadienyl)â5Râpyridine by a retroâelectrocyclization reaction