Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• enone 10 to the corresponding allylic alcohol, followed by a Au-catalyzed alkyne hydration, providing hemiketal 11. This intermediate was in equilibrium with hydroxy-ketone 12, which was suitable for a SmI2-promoted cyclization, affording intermediate 13 selectively, already bearing rings C and D. The

• radical cyclization of an alkynyl ketone as the key step. The synthesis started by a Cu-catalyzed conjugate addition of the vinyl Grignard reagent, followed by TMS α-propargylation under basic conditions, affording the TMS-alkynyl ketone 76 as the major diastereomer (Scheme 11). Originally a Au-catalyzed

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• to PdNP@ChNC, PdNP@ChsNC showed little product yield in the model reaction (Table 1, entry 6), which was surprising as our previous works showed that ChsNC was the superior catalyst support for Au-catalyzed A3 coupling reactions [16]. The XPS analysis of PdNP@ChsNC suggests that Pd is complexed to

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• one sugar anomer. Anomeric esterification using the Mitsunobu procedure [29]. Conversion of allyl glucuronate into various 1-O-esterified allyl glucuronates using anomeric Mitsunobu esterification [36][37]. Synthesis of anomeric glycosyl esters as substrates for Au-catalyzed glycosylation [40

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• other is an Au-catalyzed tandem oxazole synthesis using a primary amide, aldehyde, and alkyne [18]. These methods are reasonable for the synthesis of diverse libraries of trisubstituted oxazoles because the combination of three starting materials that are corresponding to the substituents can be readily

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

• Taofeng Shao,
• Zhiming Gong,
• Tianyi Su,
• Wei Hao and
• Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

• , the substitution pattern of the amidine moiety had little effect on the Au-catalyzed annulation reaction, whereas neutral or electron-donating groups on the aldehyde moiety gave a higher yield in comparison with the electron-withdrawing halides. Notably, bromo-substituted substrates were also

• good yields through the GBB multicomponent reaction/Au-catalyzed cyclization strategy. The described method provides a new tool for a rapid compound library generation from readily accessible starting materials. Further, the protocol tolerates a broad substrate scope, which will make it attractive for

• under vacuum and the resulting residue was purified by flash chromatography (hexane/ethyl acetate 8:1) to afford GBB adduct 4a (90% yield). Typical procedure for the Au-catalyzed cyclization reaction. To a solution of the GBB adduct 4 (0.2 mmol) in 2 mL of acetonitrile was added Au(JohnPhos)Cl (0.02

The synthesis of functionalized bridged polycycles via C–H bond insertion

• Jiun-Le Shih,
• Po-An Chen and
• Jeremy A. May

Beilstein J. Org. Chem. 2016, 12, 985–999, doi:10.3762/bjoc.12.97

• . Carbene cascade for fused bicycles. Cascade formation of bridged rings. Conformational effects. Hydrazone cascade reaction. Mechanistic studies. Gold carbene formation from alkynes. Au-catalyzed bridged-bicycle formation. Gold carbene/alkyne cascade. Gold carbene/alkyne cascade with C–H bond insertion

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• this investigation. An efficient route to a series of 1,5-di(indol-6-yl)pentenones was developed via Mo/Au-catalyzed Meyer–Schuster rearrangement of tertiary propargylic alcohol precursors. However, none of the enones underwent the desired Nazarov cyclization to a cyclopenta[f]indole. More suitable

• assemble the cyclopenta[f]indole section present in the natural product raputindole A (1). As long as the cyclopentane ring would not be installed, it was indeed possible to work with 2,3-unsubstituted, N-Boc-protected indoles. In particular, the Mo/Au-catalyzed Meyer–Schuster rearrangement of

• , obtained via Au-catalyzed Meyer–Schuster rearrangement. Assembly of 5-oxygenated bisindolylpentenones. DMB: 3,4-dimethoxybenzyl, DMFDMA: N,N-dimethylformaldehyde dimethyl acetal. Benzylic oxidation as side reaction of DMB removal. Hydroxyalkylation of N-protected indoles with β-cyclocitral and SnCl4

Versatile deprotonated NHC: C,N-bridged dinuclear iridium and rhodium complexes

• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 117–124, doi:10.3762/bjoc.12.13

• and alkynes by Au-catalyzed reactions [19][20][21]. It is not feasible to exclude the asymmetry thanks to the modification of any of the two groups on the imidazolin-2-ylidene ring for two reasons. First, H atoms on the backbone of the either saturated or unsaturated imidazolin-2-ylidene ring suppose

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

• having obtained the optimal conditions for the Au-catalyzed cyclization of carboxylic acid 15, we attempted to determine the scope and limitation of this transformation. Then we investigated the cyclization reaction of a range of substituted N-propargyl-pyrrole-2-carboxylic acids 17, 21, 25, 29 and 33

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

• °C, but also the cheaper Ph3PAuCl/AgOTf gave respectable results. Surprisingly, AuBr3 was not able to promote this cascade reaction. A special feature of this approach is that when R4 is a o-alkynylbenzene a further Au-catalyzed cascade process involving C–H activation can occur to give the

• intermediate I. In a different approach strictly related to Au-catalyzed A3-coupling, Wang and co-workers substituted the classical amine partner with triethyl orthoformate (23) to give the corresponding propargyl ethyl ethers 24 [45] (Scheme 17). After a brief screening for the best reaction conditions (i.e

• to the C=O bond of an oxocarbenium intermediate II, formed by a Au-catalyzed reaction between aldehydes and orthoformate 23. Other multicomponent processes Silver assisted multicomponent reactions Newly reported and notable synthetic strategies based on silver-mediated processes are discussed in this

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

• ready available o-alkynylaniline derivatives should provide a viable alternative to the desired C-3 fluorinated indoles. Catalytic aminofluorination of alkenes and alkynes is receiving growing attention as efficient way to construct fluorinated heterocycles [22][23]. In particular, Au-catalyzed

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• approaches toward the synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives have been reported [29][30][31][32][33][34][35][36][37][38][39][40][41][42]: (a) Ru- and Au-catalyzed cascade reactions between 2-(1H-indol-1-yl)anilines and alkynes [34][42]. (b) AlCl3-catalyzed Pictet–Spengler reactions

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

• the competitive [1][3], and [3,3]-rearrangement pathways and their respective mechanisms. Results and Discussion At the outset, the effect of ligand, counter-anion and solvent in the Au-catalyzed coupling of p-toluenesulfonylacetylene (1) with an allyl ether 2 was examined (Table 1). When Au(L)SbF6 (L

• exact nature of the [1,3]-rearrangement pathway with its stereochemical consequences and at the synthetic applications of the resulting products. Donor- and acceptor-substituted alkynes for Au-catalyzed intermolecular reactions. Proposed mechanism of the [3,3]- and [1,3]-rearrangement. Experiments to

Access to pyrrolo-pyridines by gold-catalyzed hydroarylation of pyrroles tethered to terminal alkynes

• Elena Borsini,
• Gianluigi Broggini,
• Andrea Fasana,
• Chiara Baldassarri,
• Angelo M. Manzo and
• Alcide D. Perboni

Beilstein J. Org. Chem. 2011, 7, 1468–1474, doi:10.3762/bjoc.7.170

• ][50] justifies new efforts to obtain them. This study on the Au-catalyzed cyclization of N-alkynyl-pyrrole-2-carboxamides is also focused on the effect of the alkyne substituent, as well as on the role of the solvent on the product distribution. Results and Discussion On the basis of these

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

• Alexandre Pradal,
• Chung-Meng Chao,
• Patrick Y. Toullec and
• Véronique Michelet

Beilstein J. Org. Chem. 2011, 7, 1021–1029, doi:10.3762/bjoc.7.116

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

• strategy to construct furan analogues. Du et al. reported a highly efficient Au-catalyzed cyclization of (Z)-enynols that proceeded under mild reaction conditions. This methodology provided rapid access to substituted furans 6 and stereo-defined (Z)-5-ylidene-2,5-dihydrofurans 7 in a regioselective manner

• in dichloromethane at room temperature to form the gold complex 96 in 85% yield (Scheme 17) [50]. This result could provide the experimental evidence required to support the postulated mechanism of Au-catalyzed reactions. Dual-catalyzed rearrangement reactions have been reported by Shi and co-workers

Gold-catalyzed oxidation of arylallenes: Synthesis of quinoxalines and benzimidazoles

• Dong-Mei Cui,
• Dan-Wen Zhuang,
• Ying Chen and
• Chen Zhang

Beilstein J. Org. Chem. 2011, 7, 860–865, doi:10.3762/bjoc.7.98

• ). Similarly, oxidation cleavage of 1,1-disubstituted, trisubstituted and tetrasubstituted allenes gave the expected products (Table 2, entries 8–10). In striking contrast to aromatic allenes, aliphatic allenes, such as hepta-1,2-diene and 1-(propa-1,2-dienyl)cyclohex-1-ene failed to undergo Au-catalyzed

A comparative study of the Au-catalyzed cyclization of hydroxy-substituted allylic alcohols and ethers

• Berenger Biannic,
• Thomas Ghebreghiorgis and
• Aaron Aponick

Beilstein J. Org. Chem. 2011, 7, 802–807, doi:10.3762/bjoc.7.91

• corresponding ethers. Additionally, it is reported that Reaxa QuadraPureTM MPA is an efficient scavenging reagent that halts the reaction progress. Keywords: allylic alcohol; allylic ether; Au-catalyzed; SN2'; tetrahydropyran; Introduction Saturated oxygen heterocycles are found in a wide variety of

• ]. Herein we report a study of Au-catalyzed cyclizations with different leaving groups that do not require deprotection, and data on the reaction progress that allows comparison between leaving groups and cis- versus trans-olefins. Results and Discussion At the outset, one of the important goals was to be

• it can then act as a leaving group under Au-catalyzed cyclization conditions. Several additional, commonly used, protecting groups were also screened under the reaction conditions (Figure 5). From the graph, it is apparent that benzyl (13), TBDPS (14), and THP [33] (15) could all be used, but esters

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• the Au-catalyzed isomerization of alkynyl cyclobutanols. Gold-catalyzed cycloisomerization of 1-allenylcyclopropanols. Gold-catalyzed cycloisomerization of cyclopropylmethanols. Gold-catalyzed cycloisomerization of aryl alkyl epoxides. Gold-catalyzed synthesis of furans. Transformations of alkynyl

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• coupling reactions and a Au-catalyzed asymmetric reaction, respectively. Suzuki–Miyaura and Heck–Mizoroki coupling reactions catalyzed by NHC–Pd(II) complex The Pd-catalyzed coupling reaction is one of the most powerful methods for the formation of carbon–carbon bonds in organic synthesis [60][61][62][63

• allylic acetates [75][76], carbene-transfer reactions from ethyl diazoacetate [77], formation of conjugated enones and enals [78], regio- and stereoselective synthesis of fluoroalkenes [79], and so on [80][81][82][83][84][85]. However, reports on NHC–Au catalyzed asymmetric reactions are rare [86]. The