A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• aminide 7 in good yield on a gram scale (Scheme 1b). With the novel 3-aminoimidazo[5,1-b]oxazol-6-ium salt in hand, we examined its use as an NHC precursor for the preparation of late transition metal complexes. Treating compound 9a with triethylamine and either dimethyl sulfide gold(I) chloride or copper

Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy

• Jiayue Fu,
• Bingbing Li,
• Zefang Zhou,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169

• ) and tert-butyldimethylsilyl chloride (TBSCl) (Scheme 5). To find the best cycloisomerization conditions, the 1,5-enyne substrate 10 was subjected to different reaction conditions as listed in Table 1. It was observed that [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]gold(I) chloride (IPrAuCl

• ). The Au(I)-catalyzed cycloisomerization reaction of substrate 10 occurred under the catalysis of 5 mol % [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]gold(I) chloride (IPrAuCl) and 5 mol % silver hexafluoroantimonate (AgSbF6) [25][26] in anhydrous DCM at room temperature for 2 h forming a benzene

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• molecular host to modulate the reactivity. Recently, Reek and co-workers have constructed an M12L24 nanosphere by treating the bispyridyl 120° ligand 30 with a Pd(II) precursor [72]. Here, the ligand 30 is optimally functionalized with a phosphine gold(I) chloride moiety so that the metal catalyst will

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• used as the substrate for the gold(I) catalyzed reaction (Scheme 1). Mixing five mol % of gold(I) chloride and two equivalents of TIPS-EBX with a diethyl ether solution of 2 under ambient conditions yielded a mixture of ethynyl-substituted dipyrromethanes as judged by mass spectrometry. The product

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• .12.264 Abstract The mesomeric betaine imidazolium-1-ylphenolate forms a borane adduct with tris(pentafluorophenyl)borane by coordination with the phenolate oxygen, whereas its NHC tautomer 1-(2-phenol)imidazol-2-ylidene reacts with (triphenylphosphine)gold(I) chloride to give the cationic NHC complex [Au

• on reaction with (triphenylphosphine)gold(I) chloride in boiling anhydrous THF under a nitrogen atmosphere, under which conditions the colorless gold complex [Au(6B)2][Cl] (9) is formed in 60% yield (Scheme 1). The protons of the OH resonate at δ = 10.34 ppm in DMSO-d6, and the 13C NMR chemical shift

• -butyl-1-(2-hydroxyphenyl)-1H-imidazolium-2-yl)gold monochloride (9): A solution of 0.43 g (0.20 mmol) of 2-(3-butyl-1H-imidazolium-1-yl)phenolate in 5 mL of anhydrous THF was treated with 0.05 g (0.10 mmol) of (triphenylphosphine)gold(I) chloride and stirred under an inert atmosphere overnight at reflux

Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX

• Gergely L. Tolnai,
• Jonathan P. Brand and
• Jerome Waser

Beilstein J. Org. Chem. 2016, 12, 745–749, doi:10.3762/bjoc.12.74

• mixture was stirred at 40 °C for 2 min. Gold(I) chloride (2.3 mg, 10 µmol, 0.05 equiv) was added in one portion. The reaction tube was sealed and stirring was continued for 24 h at 40 °C. Afterwards, the mixture was diluted with EtOAc (50 mL), and the organic layer was washed with a mixture of water (2.5

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• the gold(I)-to-gold(III) oxidation and stabilizes the gold(III) species, thereby facilitating the oxidative coupling reactions. Experimental Preparation of triarylpyridylidene-gold(I) chloride [AuCl(PyC)]: A 10 mL Schlenk tube containing a stir bar was dried under vacuum and filled with N2 after

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• catalysis (Table 16) [244]. Besides copper(I) iodide several other copper salts effectuated the reaction albeit in lower yields as did silver(I) iodide, palladium(II) chloride and platinum(II) chloride. Other transition metal catalysts such as gold(I) chloride, nickel(II) chloride and cobalt(II) chloride

On the proposed structures and stereocontrolled synthesis of the cephalosporolides

• Sami F. Tlais and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2012, 8, 1287–1292, doi:10.3762/bjoc.8.146

• silyl ether 19 with the (R)-propylene oxide produced the internal alkyne 20 (Scheme 5). Gold(I) chloride in MeOH induced the spiroketalization of alkyne 20 with concomitant cleavage of the PMP acetal and partial cleavage of the TBS ether. After completion of the desilylation with TBAF, a mixture of 5,5

Combination of gold catalysis and Selectfluor for the synthesis of fluorinated nitrogen heterocycles

• Antoine Simonneau,
• Pierre Garcia,
• Jean-Philippe Goddard,
• Virginie Mouriès-Mansuy,
• Max Malacria and
• Louis Fensterbank

Beilstein J. Org. Chem. 2011, 7, 1379–1386, doi:10.3762/bjoc.7.162

• of AuCl3, a lower yield of 3a was observed (14%) with trace amounts of 4a and 5a (2% yield each, Table 1, entry 3). The use of the N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) gold(I) chloride as catalyst led to the formation of 3a in 65% yield, together with 13% yield of 4a. Under these

• conditions, the formation of 5a was not detected (Table 1, entry 4). Gold(I) phosphite catalysts gave 3a and 4a in low yields (Table 1, entries 6 and 7). A similar result was observed with tri(tert-butyl)phosphine gold(I) chloride (Table 1, entry 8). The dinuclear complex, dppm(AuCl)2, led to 3a and 5a in a

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• tetrahydropyran 24 were produced by an efficient gold(I) chloride catalyzed cycloisomerization of 2-alkynyl-1,5-diol 22 [28]. A plausible mechanism for the gold-catalyzed transformation of dioxabicyclo[4.2.1]ketal 25 to tetrahydropyran 31 is outlined in Scheme 5. The gold catalyst activates one of the oxygen

The role of silver additives in gold-mediated C–H functionalisation

• Scott R. Patrick,
• Ine I. F. Boogaerts,
• Sylvain Gaillard,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2011, 7, 892–896, doi:10.3762/bjoc.7.102

• of 5. This observation clearly shows that silver can have a positive role in the carboxylation of C–H bonds. Conclusion The C–H functionalisation of arenes using (NHC)gold(I) complexes has been shown to be significantly affected by the leaving group on the gold. The gold(I) chloride may only react by

Highly efficient gold(I)-catalyzed Overman rearrangement in water

• Dong Xing and
• Dan Yang

Beilstein J. Org. Chem. 2011, 7, 781–785, doi:10.3762/bjoc.7.88

• environmentally benign and scalable protocol, a series of C3-alkyl substituted allylic trichloroacetamides were synthesized in good to high yields. Keywords: allylic trichloroacetamides; allylic trichloroacetimidate; gold(I) chloride; Overman rearrangement; water; Introduction The aza-Claisen rearrangement of

A gold-catalyzed alkyne-diol cycloisomerization for the synthesis of oxygenated 5,5-spiroketals

• Sami F. Tlais and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2011, 7, 570–577, doi:10.3762/bjoc.7.66

• cephalosporolides. Gold(I) chloride in methanol induced the cycloisomerization of a protected alkyne triol with concomitant deprotection to give a strategically hydroxylated 5,5-spiroketal, despite the potential for regiochemical complications and elimination to furan. Other late transition metal Lewis acids were

• conditions that ultimately resulted in the acquisition of our target structures [28]. Gold(I) chloride emerged as the best choice for the desired transformation. The key precedents for the desired cycloisomerization are shown in Scheme 3, although many methods are available [30][31][32][33][34] and no

• (Table 1, entry 1) resulted in decomposition of the substrate, but at room temperature the spiroketal was obtained in modest yield (Table 1, entry 2). Reactions involving Ziese’s dimer were disappointing (Table 1, entry 3), but gold(I) chloride in methylene chloride (cf. Scheme 3, Reaction 3) gave more