Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• as a base (Scheme 2). Gold catalysis is an excellent method for constructing complex chemical architectures in a mild manner that would be difficult to achieve using other reactions [41][47][48][49][50][51][52][53]. Reaction of propargyl ester 13 with AuCl3 resulted in the formation of 14, which is

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• three-coordinated -[Ag(NO2)]-L- chains, linked together by hydrogen bonds. The complex demonstrated to be more suited to aliphatic than aromatic aldehydes, whereas the presence of an EWG on the aldehyde resulted in low reaction yields. Gold catalysis The first example of a gold-catalyzed synthesis of

Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

• Antonio Arcadi,
• Emanuela Pietropaolo,
• Antonello Alvino and
• Véronique Michelet

Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42

• access to 3,3-difluoro-2-aryl-3H-indoles and 3-fluoro-2-arylindoles are described. An unprecedented aminoauration/oxidation/fluorination cascade reaction of 2-alkynylanilines bearing a linear alkyl group on the terminal triple bond is reported. Keywords: 2-alkynylanilines; fluorination; gold catalysis

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

• Mathieu Morin,
• Patrick Levesque and
• Louis Barriault

Beilstein J. Org. Chem. 2013, 9, 2625–2628, doi:10.3762/bjoc.9.297

• ; cyclization; gold(I); gold catalysis; heterocycles; regioselectivity; Introduction In the last decade, phosphino and NHC–gold complexes have become prominent catalysts for the addition of nucleophiles to alkenes, alkynes and allenes [1][2][3][4][5][6][7][8][9][10][11]. Owing to the high affinity of gold(I

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• intends to summarize the recent progresses in the field, with particular emphasis on mechanistic details. Keywords: alkene; gold catalysis; mechanism; organic synthesis; Review 1 Introduction Homogeneous gold catalysis is emerged as one of the most powerful means for the activation of C–C multiple bonds

• point of view [33]. Although many metal and Brønsted acid assisted processes have been documented the high functional group tolerance of gold complexes combined with their high efficiency in the electrophilic activation of C–C multiple bonds have made gold catalysis an important tool for the

• reactivity of these substrates [62]. Due to the ability of gold complexes to act as σ- and π-acids, gold catalysis gained a prominent role in the activation of allylic alcohols, delivering of water as the side-product. As the topic has been recently extensively reviewed by Aponick and Biannic [7], only the

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C₃-building block

• Volker M. Schmiedel,
• Stefano Stefani and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291

• . Keywords: chiral auxiliaries; gold catalysis; jaspine B; lithiated alkoxyallenes; natural product synthesis; pachastrissamine; tetrahydrofurans; Introduction Jaspine B, also known as pachastrissamine (1, Scheme 1), is an anhydrophytosphingosine derivative, isolated 2002 from the marine sponge Pachastrissa

• block and allowed the synthesis of both enantiomers of the natural product in a fairly short manner (seven steps starting from the allene). The 5-endo-cyclization of allenyl alcohols 12 and 13 by gold catalysis afforded a separable mixture of diastereomeric dihydrofurans 14 and 15 in good yield

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• access to various vinyl ethers. A catalytic amount of copper triflate was identified as the significant additive in promoting this transformation. Both aromatic and aliphatic alkynes are suitable substrates with good to excellent yields. Keywords: alkyne; copper salt; diketone; gold catalysis; vinyl

• ether; Introduction The past decade has witnessed the fast growth of homogeneous gold catalysis as one of the important branches in transition-metal chemistry [1][2][3][4][5][6][7][8][9]. The utility of cationic gold(I) complexes as π-carbophilic acids toward alkyne and allene activation renders them

• catalysis, which is a very active research area in the gold catalysis community. Evaluation of distinct O-nucleophiles toward intermolecular addition to alkynes is currently underway in our group. Intermolecular O-addition to alkynes: challenge and opportunity. Acid as the critical additive for optimal

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• : asymmetric catalysis; DFT; 1,3-dipolar cycloaddition; gold catalysis; NICS; NTR; oxazolones; prolines; Introduction The synthesis of α-amino acids employing an α-amino carbonyl template constitutes the most straightforward route to introduce the α-side chain [1]. As a valid example, oxazol-5-(4H)-ones

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• processes. Keywords: alkyne; allene; asymmetric catalysis; cycloaddition; enantioselective; gold; gold catalysis; Introduction In the past decade, there have been extraordinary advances in the development of novel stereoselective gold(I)-catalyzed transformations [1][2][3][4][5][6][7][8][9][10]. In this

• context, enantioselective gold catalysis has been identified as a particularly challenging goal because the linear two-coordination mode of gold(I) complexes and the out-sphere π-activation usually associated to carbophilic gold catalysts [11] places ligands far from the reacting centers, thus limiting

Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes

• Ana M. Sanjuán,
• Alberto Martínez,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2013, 9, 2242–2249, doi:10.3762/bjoc.9.263

• hydroxy(methoxy)-functionalized dihydronaphthalene derivatives is highly remarkable in the context of the observed reaction pathways for the cycloisomerizations of 1,6-enynes bearing a trisubstituted olefin. Keywords: catalysis; dihydronaphthalenes; gold; gold catalysis; hydroxycyclization; selectivity

Synthesis of axially chiral gold complexes and their applications in asymmetric catalyses

• Yin-wei Sun,
• Qin Xu and
• Min Shi

Beilstein J. Org. Chem. 2013, 9, 2224–2232, doi:10.3762/bjoc.9.261

• product in moderate yields and up to 29% ee. Keywords: asymmetric gold catalysis; chiral Au catalysts; gold-π interaction; NHC gold complex; Introduction After the long-held assumption of the non-reactivity of gold complexes, numerous reactions catalyzed by gold complexes have emerged in the last 2

• decades [1][2][3][4][5][6][7][8][9]. In the past few years, reports on gold-catalyzed organic transformations have increased substantially [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Homogeneous gold catalysis has proven to be a powerful tool in organic synthesis

• far, several axially chiral NHC–gold catalysts based on binaphthyl skeleton such as 1 and 2 [46][49] have been reported with good to excellent chiral inductions in asymmetric gold catalysis (Figure 1). Encouraged by these results, we attempted to develop novel types of axially chiral NHC–gold

Synthesis, characterization and luminescence studies of gold(I)–NHC amide complexes

• Adrián Gómez-Suárez,
• David J. Nelson,
• David G. Thompson,
• David B. Cordes,
• Duncan Graham,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2013, 9, 2216–2223, doi:10.3762/bjoc.9.260

• fluorescence measurements have allowed the identification of their excitation and emission wavelengths (λmax). These studies revealed that by selecting the appropriate amine ligand the emission can be easily tuned to achieve a variety of colors, from violet to green. Keywords: fluorescence; gold; gold

• catalysis; N-heterocyclic carbenes; synthesis; Introduction The synthesis of organogold complexes has recently attracted wide attention due to their considerable range of applications, in areas such as materials and medicinal chemistry, as well as their potential role as reaction intermediates or new

Gold-catalyzed glycosidation for the synthesis of trisaccharides by applying the armed–disarmed strategy

• Abhijeet K. Kayastha and
• Srinivas Hotha

Beilstein J. Org. Chem. 2013, 9, 2147–2155, doi:10.3762/bjoc.9.252

• oligosaccharides. The gold catalysis for glycosidation reactions, in which alkynylated glycosides are used, has emerged as one of the versatile options in this regard. A cleavage of the interglycosidic bond that was thought to be due to the higher reaction temperature and the acidic medium was observed during the

• moiety were screened. It was found that 1-ethynylcyclohexanyl (Ech) glycosides are suitable for carrying out the glycosidation at 25 °C in the presence of 5 mol % each of AuCl3 and AgSbF6. Subsequently, Ech-glycosides were observed to be suitable for the synthesis of trisaccharides under gold catalysis

• % yield under gold-catalysis conditions (Scheme 3). Importantly, the hydrolysis of benzyl ethers was not observed when the gold catalysis reactions were performed at room temperature [23][24][25][26][27][28][38]. From the above observations, the high temperature (70 °C) of the glycosidation and the

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• hydroarylation steps. Keywords: alkyne; chromene; gold; gold catalysis; hydroarylation; iodine; Introduction The structure of 2H-chromene embodies a relevant heterocyclic motif, which is present in naturally occurring compounds [1][2][3][4][5][6] and encodes interesting properties that renders it attractive

Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach

• Thi Thanh Huyen Trinh,
• Khanh Hung Nguyen,
• Patricia de Aguiar Amaral and
• Nicolas Gouault

Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242

• -alanine. The key step to access the enantiopure pyridone intermediate was achieved by a gold-mediated cyclization. Finally, various transformations afforded the natural product in a few steps and good overall yield. Keywords: epimyrtine; gold; gold catalysis; heterocycles; hydroamination; quinolizidine

• stereoselective synthetic routes are still being sought after. In the past decades, gold catalysis has emerged as an important tool in a plethora of fields of synthetic organic chemistry, and after methodological investigations [11][12][13][14][15][16], the good functional group compatibility of gold catalysts

• renders gold catalysis a straightforward protocol in the realm of the synthesis of natural products [17][18]. Herein we report a short total synthesis of (−)-epimyrtine employing an alternative strategy by using a gold(I)-catalyzed hydroamination of a β-aminoynone as the key step. Actually, cyclization of

Gold catalysis for organic synthesis II

• F. Dean Toste

Beilstein J. Org. Chem. 2013, 9, 2040–2041, doi:10.3762/bjoc.9.241

• F. Dean Toste Department of Chemistry, University of California, Bekeley, CA, USA 10.3762/bjoc.9.241 Keywords: gold catalysis; Two years have now passed since the publication of the first Thematic Series on gold catalysis for organic synthesis in the Beilstein Journal of Organic Chemistry. In

• the intervening time, the pace of progress and discovery in the field has continued unabated. Many of these advancements are exemplified in the more than twenty contributions that have been collected in this second Thematic Series. Many of the early examples of homogeneous gold-catalysis focused on

• tandem or domino process that can be employed for the synthesis of complex polycyclic structures. These articles demonstrate the power of gold catalysis for the construction of complex structures, including the development of tandem processes, the expedient synthesis of heterocyclic structures, and

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• ; gold; gold catalysis; hydrophenoxylation; silver-free; single component; solvent-free; Introduction The use of gold compounds to promote hydroelementation reactions has grown tremendously over the past few years [1][2][3][4][5]. Using this approach, a host of different organic substrates have been

Gold-catalyzed reaction of oxabicyclic alkenes with electron-deficient terminal alkynes to produce acrylate derivatives

• Yin-wei Sun,
• Qin Xu and
• Min Shi

Beilstein J. Org. Chem. 2013, 9, 1969–1976, doi:10.3762/bjoc.9.233

• reactions is also discussed. Keywords: gold catalysis; oxabicyclic alkenes; substituted acrylates; Introduction Oxabicyclic alkenes are common intermediates in organic synthesis since these compounds can be easily prepared and have a high reactivity for further transformations [1][2][3][4][5][6][7][8

An approach towards azafuranomycin analogs by gold-catalyzed cycloisomerization of allenes: synthesis of (αS,2R)-(2,5-dihydro-1H-pyrrol-2-yl)glycine

• Jörg Erdsack and
• Norbert Krause

Beilstein J. Org. Chem. 2013, 9, 1936–1942, doi:10.3762/bjoc.9.229

• ; amino acids; cuprates; furanomycin; gold catalysis; Introduction In 1967, Katagiri et al. reported the isolation of a novel antibiotic from the culture broth of the fungus Streptomyces threomyceticus [1]. The compound acts as a competitive antagonist for isoleucine in vitro and hampers the growth of

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

• Kegong Ji,
• Jonathan Nelson and
• Liming Zhang

Beilstein J. Org. Chem. 2013, 9, 1925–1930, doi:10.3762/bjoc.9.227

• the use of a P,S-bidentate ligand, which is proposed to enable the formation of tris-coordinated and hence less electrophilic gold carbene species. α-Carboxy α,β-unsaturated ketones/aldehydes can be obtained with fair to excellent yields. Keywords: enone; gold catalysis; oxidation; propargyl

• regioselectivities of this oxidation with different types of internal alkynes, we examined propargylic carboxylates, which have served as a versatile platform for the development of a diverse range of gold catalysis [21]. Herein we report our findings and the development of a reliable synthesis of α-carboxy α,β

• substrates from other well established, facile gold catalysis to the formation of distinctively different functional products in the presence of oxidants. The relatively low selectivity (i.e., ~7:1) of 5a-OAc over 5a-H was drastically improved upon catalyst screening. It was eventually found that the ratio

Gold(I)-catalysed one-pot synthesis of chromans using allylic alcohols and phenols

• Eloi Coutant,
• Paul C. Young,
• Graeme Barker and
• Ai-Lan Lee

Beilstein J. Org. Chem. 2013, 9, 1797–1806, doi:10.3762/bjoc.9.209

• allylation/intramolecular hydroalkoxylation sequence. The reaction is mild, practical and tolerant of a wide variety of substituents on the phenol. Keywords: allylic alcohols; chromans; Friedel–Crafts; gold catalysis; heterocycles; Introduction Chromans (dihydrobenzopyrans) are important and ubiquitous

• Friedel–Crafts allylation of phenols has been reported by Chan and co-workers [73], there have been no reports on the direct synthesis of chromans [74] using gold catalysis [75] with phenols and allylic alcohols prior to our example shown in Scheme 1. Since the reaction is very practical: distilled

Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• -acyloxyalkynyl ketones were efficiently converted into highly substituted furans with 2.5 mol % of triflimide (triphenylphosphine)gold(I) as a catalyst in dichloroethane at 70 °C. Keywords: alkynyl ketones; cycloisomerization; furans; gold-catalysis; 1,2-migration; Introduction Furans are an important class of

• , 3-benzyloxypropyl (Table 2, entries 9–12), were fully compatible with our gold-catalysis giving furans 2i–l in good yields. Two different mechanistic hypotheses could be envisaged in the rearrangement of γ-acyloxyalkynyl ketones into furans based on multifaceted gold-catalyst properties, i.e. the

Zinc–gold cooperative catalysis for the direct alkynylation of benzofurans

• Yifan Li and
• Jérôme Waser

Beilstein J. Org. Chem. 2013, 9, 1763–1767, doi:10.3762/bjoc.9.204

• successful in the case of the more complex drug 8-methoxypsoralen (8-MOP). Keywords: alkynylation; benzofurans; cooperative catalysis; direct functionalization; gold catalysis; hypervalent iodine; Introduction Benzofurans are important heterocycles frequently encountered in both bioactive compounds and

Gold-catalyzed cyclization of allenyl acetal derivatives

• Dhananjayan Vasu,
• Samir Kundlik Pawar and
• Rai-Shung Liu

Beilstein J. Org. Chem. 2013, 9, 1751–1756, doi:10.3762/bjoc.9.202

• of the acetate group at the allyl cation intermediate. Keywords: allenyl acetals; 5-alkylidenecyclopent-2-en-1-ones; cyclization; gold catalysis; Introduction Gold-catalyzed cyclization/cycloaddition reactions [1][2][3][4][5] are useful synthetic methods to construct complicated carbo- and

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• ]-rearrangement products through the formation of a tight ion–dipole pair. Keywords: gold catalysis; intermolecular coupling; [1,3]-rearrangement; [3,3]-sigmatropic rearrangement; sulfonylacetylene; Introduction Homogeneous gold catalysis has been established during the last decade as a prominent tool in

• organic chemistry, mediating a variety of C–C and C–X (heteroatom) bond formations, various tandem reactions and rearrangements [1]. Despite these significant advances, overcoming entropic penalty in intermolecular coupling of alkenes with alkynes is still a major challenge in gold catalysis, reflected by

• of an excess component. Expanding upon the intermolecular coupling reactions of readily available alkenes with alkynes would significantly enhance the synthetic utility of gold catalysis and therefore should find fruitful applications. While it has been known for a long time that allyl alcohols