Phosphine imidazolyl

Field LD, Messerle BA, Vuong KQ, Turner P. Rhodium(I) and iridium(I) complexes containing bidentate phosphine-imidazolyl donor ligands as catalysts for the hydroamination and hydrothiolation of alkynes. Dalton Trans. 2009 3599-3614. 

Thereby, the presence of tertiary monophosphines is critical, because both polymeric (26) and cyclic tetrameric (24 and 25) complexes can be obtained depending on the phosphine added to the reaction mixture. Furthermore, with some of the phosphines rapid decomposition and deposition of metallic silver occurs. In the macrocyclic molecules 24 and 25 a pair of silver atoms is bridged by two bis(l-imidazolyl)borate moieties, with a transannular Ag Ag distance of 8.61 A for 24 and 8.89 A for 25. The conformations of 24 and 25 are... 

In the reaction of unprotected uridine with tri(imidazolyl-l)phosphine (ratio 1 1.5) under mild conditions (THF, — 78° to 0 °C, 10 min) and subsequent oxidation with iodide, two types of polymers [(Up)n (n = 2-6) and (Up)nU (n = 2—5)] are formed. Additives such as metal cations or polynucleotides (poly U and poly A) acting as templates in the oxidation process showed a significant effect on the ratio of the 3, 5 -linked to 2, 5 -linked oligomer 17 177 ... 

The intemucleotide phosphordiester bonds are composed of both 3, 5 - and 2, 5 -linkages. It was noted that tri(imidazolyl-l)phosphine does not attack the 5 -OH of unprotected uridine. 

Other applicable imidazole-transfer reagents include JV V -sulfinyldiimidazole (B), diimidazolylsulfide (C) and tris(imidazolyl)phosphine (D). The 1,2,4-triazolyl group is transferred by A AT -sulfinyldi-1,2,4-triazole (E) or tris(l,2,4-triazolyl)phosphine (F). 

In an effort to apply the cooperative principles of metalloenzyme reactivity, involving a combination of metal-ligand and hydrogen bonding, we have reported a ruthenium catalyst incorporating imidazolyl phosphine ligands that efficiently and selectively hydrates terminal alkynes (5). We subsequently found that application of pyridyl phosphines to the reaction resulted in a >10-fold rate enhancement and complete anti-Markovnikov selectivity, even in the... 

The use of a lipophilic zinc(II) macrocycle complex, 1-hexadecyl-1,4,7,10-tetraazacyclododecane, to catalyze hydrolysis of lipophilic esters, both phosphate and carboxy (425), links this Section to the previous Section. Here, and in studies of the catalysis of hydrolysis of 4-nitrophenyl acetate by the Zn2+ and Co2+ complexes of tris(4,5-di-n-propyl-2 -imidazolyl)phosphine (426) and of a phosphate triester, a phos-phonate diester, and O-isopropyl methylfluorophosphonate (Sarin) by [Cu(A(A(A/,-trimethyl-A/,-tetradecylethylenediamine)l (427), various micellar effects have been brought into play. Catalysis of carboxylic ester hydrolysis is more effectively catalyzed by A"-methylimidazole-functionalized gold nanoparticles than by micellar catalysis (428). Other reports on mechanisms of metal-assisted carboxy ester hydrolyses deal with copper(II) (429), zinc(II) (430,431), and palladium(II) (432). 

The procedure described below can be applied to several derivatives of the parent tris(imidazolyl)phosphine ligand. The details are provided for preparing tris(l,4-diisopropylimidazolyl)phosphine, but the same route can be used to synthesize tris(l-isopropyl-4-tm-butylimidazolyl)phosphine, tris(l-iso-propyl-4-phenylimidazolyl)phosphine, and tris( 1 -isopropyl-4-methylmidaz-olyl)phosphine, starting with commercially available 1-bromopinacolone, 2-bromoacetophenone, and 1-chloroacetone, respectively. 

Cyclic amines with a great variety of A-substituents have been described, many with biologically significant groups, e.g., imidazolyl. Others include methyl-phosphonic and -phosphinic acids,147 methyl-sulfonate,148 quinolin-2-ylmethyl, anthraquinon-2-ylmethyl, 2-(3-hydroxy-pyridyl)methyl, 2-methoxyethyl,149 2-methylthioethyl,150 thiophenyl, pyrazolyl, etc. 

The catalyst must act as a Lewis base. The structural features of Kocovsky s catalysts (e.g., 35) are detailed right below Table 4.1 (a) Valine i Pr (optimized) (b) N Me (c) N CH—O (formyl) and (d) another anilide group in the molecule. Other catalysts share similar features, in some cases the formamide group can be replaced by a picolinyl (41 43) of sulfinamide group (46). Other functional groups that can be considered are, for example, imidazolyl (high affinity to Si), oxazolidinyl, N oxide, phosphine oxides, and so on. 

A rn 5(imidazolyl)phosphine zinc(II) complex 3. where X is a monodentate ligand (=OH. I , and NO3 ), was synthesized and examined by x-ray crystal analysis. The zinc )-bound OH complex is claimed to be the first structurally characterized monomeric zinc(II) hydroxide complex sequestered by three imidazole groups and. therefore, may become an excellent structural model for the active site of carbonic anhydrase. 

Others have shown that p- n ri -peroxo-dicopper(II) species also form with tris(l-R-4-R -imidazolyl)phosphines or trisubstituted triazacyclononane (TACN) ligands. For the latter case, Tolman and co-workers discovered important new chemistry. Scheme 3. Oxygmation of 4a can give both Cu/Oj = 2 1 adducts 5b or 5 (Scheme 3 Chart 2). For R = /Pr in CHaCb solvent at low temperatures, 5b (Xmax = 366 nm, v(0-0) = 722... 

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