Diene-gold

A number of alkyne-gold complexes have been structurally characterized [17-21] and studied in solution [22-25]. Well-characterized complexes of gold(l) with aUcenes are also known [26 2] and their structures have been studied in solution [38, 39, 43, 44]. The solid state structures of cationic aUene—gold(I) [45] and diene-gold(I) [46] have also been determined. 

An unusual [4+1] cycloaddition gold-catalysed reaction between propargyl tosylates 102 and imines 103 led to the formation of eyclopent-2-enimines 104 (Scheme 5.27) [27], A possible mechanism for this reaction involves a 1,2-migration of the tosylate that generates the 1,3-diene 105 followed by a Nazarov-hke cyclisation. 

Heteronuclear /x-oxo complexes have been prepared by oxo/halide exchange reactions, then the reaction of metal halide complexes with the gold oxonium species gives complexes of the Jy [Rh2(dien)2 0(AuPPh3)2 (BF4)2 (476) (dien = COD, NBD) or [Pt(COD)2 OAu(PR3) 2] 2725 J "... 

Gold(I)-catalyzed synthesis of dihydrobenzo[ >]furans from aryl allyl ethers was reported as depicted below <06SL1278>. Highly efficient AuCl3/AgOTf-catalyzed atom-economical annulation of phenols with dienes was developed. This annulation generated various dihydrobenzo[ >]furans under mild conditions <06OL2397>. 

R. Adams and M.H. Gold, Synthesis of 1,3-diphenyldihydroisobenzofurans, 1,3-diphenylisoben-zofurans and o-dibenzoylbenzenes from the diene addition products to dibenzoylethylene, J. Am. Chem. Soc., 62 56-61 (1940). 

Gold(III) complexes are isoelectronic and usually isostructural with those ofPt(II). Gold(III) complexes such as [Au(en)2]3+, [AuCl(dien)]2+, and [Au(cyclam)]3+ bind rapidly to DNA, with preference for GC se-... 

Research in this area was developed further by Li et at. using 1,3-dienes 64 for the gold-catalyzed annulation of phenols and naphtols [58, 59]. These generated various dihydrobenzofuran derivatives. The best yields were achieved when the catalytic system included enough AuCl3 and silver salt to remove halogen atoms and deliver cationic gold. 

This methodology was later successfully applied to cyclic alkenes, dienes and trienes [59]. The tentative mechanism proposed by Li et al. involves the activation of the —H bond by gold(I) species (from in situ reduction of gold(III)). Then, the reaction is followed by the alkene attack on the alkylgold hydride intermediate. 

After compiling many results obtained in similar studies of different substrates (alkenes, dienes, alkynes and so on), the results cannot be correlated to draw definitive conclusions due to the wide variety of parameters that can influence the reaction (substrates, catalyst precursors, supports, pressure, temperature and so on) [9, 208-214]. This is maybe the main reason why there are no clear mechanistic explanations for this simple reaction, unlike homogeneous gold-catalyzed processes. 

Fi20,Ru2C24H26, Ruthenium(II), p-aqua-bis-(p.-trifluoroacetato)bis[(-q l-cycloocta-1,5-diene)(trifluoracetato)-, 26 254 Fi5AuSC22H8, Gold(III), tris(penta-... 

Several gold(I) olefin complexes have been prepared, although the exact constitution was often in some doubt. The first olefin complex was reported (73) in 1964, when white crystals were obtained from the reaction of cycloocta- 1,5-diene (cod) with AuCl or HAuC14. These products were believed to be a dimeric aurous complex [Au2Cl2(cod)]. Subsequent reports, however, showed that although gold(I) chloride reacted (74) to give... 

Compensation trends are found in the kinetic data reported for the catalytic hydrogenation of several hydrocarbons on bimetallic systems, including the reactions of ethylene on Ni-Cu and on Ni-Au alloys (252), buta-1,3-diene on Ni- Cu alloys (183), benzene on Ni-Cu (but the behavior of benzene on Cu-Pd was less obviously compensatory) (253), and the liquid phase hydrogenation of nitrobenzene on Pd Ag alloys (56). The kinetic characteristics of but-2-yne on Pd-Au alloys (28) was different in that E underwent little variation, while the value of log A systematically diminished as the proportion of palladium in the alloys was reduced. It was concluded that palladium was the active constituent and gold was an inactive diluent. 

Cyclohexyldienyl complexes, with Ti(IV), 4, 327 Cyclohexylisocyanides, with gold(I) halides, 2, 281 Cyclohexylphosphine, for semiconductor growth, 12, 9 Cyclohexyl selenides, preparation, 9, 480 Cyclohydrocarbonylation alkenes, 11, 515 alkynes, 11, 522 dienes, 11, 522 overview, 11, 511-555 for ring expansion, 11, 527 Cycloisomerizations, via silver catalysts, 9, 558 Cyclomanganation, product types, 5, 777-778 Cyclometallated azobenzenes, liquid crystals, 12, 251 Cyclometallated complexes for OLEDs... 

Ferrocenyl ligands, via zinc reagents, 9, 120 Ferrocenylmethyl phosphonium salts, with gold(I), 2, 274 Ferrocenylmonophosphine, in styrene asymmetric hydrosilylation, 10, 817 Ferrocenyl oxazolines, synthesis, 6, 202 Ferrocenylphosphines with chromium carbonyls, 5, 219 in 1,3-diene asymmetric hydrosilylation, 10, 824-826 preparation, 6, 197 various complexes, 6, 201 Ferrocenylselenolates, preparation, 6, 188 Ferrocenyl-substituted anthracenes, preparation, 6, 189 Ferrocenyl terpyridyl compounds, phenyl-spaced, preparation 6, 188 Ferrocifens... 

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