Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• hence it leads to the formation of racemic products with moderate yields (Scheme 44). 1,6-Enynes 156 underwent smooth hydroxylative carbocyclization in the presence of catalytic Hg(OTf)2. As an example, 3-methylene five-membered cyclic derivatives 157 were synthesized by Nishizawa et al. via the Hg(OTf

• )2-catalyzed hydroxylative carbocyclization of 1,6-enyne 156 (Scheme 45) [104]. It was observed that from 1,7-enynes, six-membered rings were formed in low to moderate yield while from 1,8-enynes, uncyclized hydrated products were isolated. as major products along with different byproducts. In a Hg

• experimental evidence that alkynes would first form a π-complex with Hg(OTf)2, followed by vinylmercuration, demercuration, and eventually isomerizes to allenene. In 2003, a carbocyclization with a catalytic quantity of mercury salt was used to efficiently synthesize dihydronapthalene derivative 161 from

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• in Fe(III)-promoted hydroalkylation/cyclization cascades (Scheme 26A) [93]. Here, the carbocyclization occurred via a SN2 mechanism between the enolate intermediate and the tethered halide (Scheme 26B). Using arylidene diones 67 as radical acceptors, spiro compounds 69 were obtained in moderate to

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• best of our knowledge, there are no reports on the practical synthesis of disubstituted 2-fluoroalkylated indenols so far. Transition-metal-catalyzed carbocyclization reactions of alkynes with benzene derivatives having a leaving group X (X = Br, I, OTs, B(OH)2) have been widely considered as one of

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• π-extension through a Suzuki–Miyaura coupling, Sonogashira coupling, and electrophilic alkyne carbocyclization [18]. Given the successful synthesis of the angularly fused phosphahelicenes, we became interested in the further exploitation of 7-hydroxybenzo[b]phosphole as an intermediate for the

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

• Gisela V. Saborit,
• Carlos Cativiela,
• Ana I. Jiménez,
• Josep Bonjoch and
• Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

• outlined in Figure 1, which for the sake of clarity omits the substituents not involved in the bond-forming step in the final ring closure. Almost all the strategies developed to date involve the formation of the C3–C3a bond in the ring-closing step leading to the hydrindane nucleus. The carbocyclization

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• ][20][21], by microbial oxidation; 3) carbocyclization involving organometallic intermediates (Ferrier II reaction [22] performed on 6-O-acyl-hex-5-enopyranosides followed by reduction [23][24]; trialkylaluminium [25][26] or titanium(IV)-assisted [27] conversion of hex-5-enopyranosides and SmI2

• findings have been reported so far [46][47], the regioselective protection of inositols is still a troublesome area due to the comparable reactivity of the secondary hydroxy functions. Therefore, the carbocyclization of a selectively protected dicarbonyl sugar, namely the L-lyxo derivative 20, whose

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• depicted in Figure 9 and Figure 11 were observed. Previously palladium(II)-alkyne π-complexes have been proposed as intermediates in Pd(II)-catalyzed diamination of alkynes [63], enyne coupling [64], hydroarylation of alkynes [65], inramolecular carbocyclization [66] and other reactions. Some types of

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• phenanthridine (Scheme 20) [44]. The synthesis by multicomponent tandem reaction/carbocyclization starts with the formation of a 4-aryl-3-arylethynylisoquinoline from 2-bromobenzaldehyde/tert-butylamine/1,3-diyne. The second (in situ) step is based on the ring closure, either via gold/silver-catalysed

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• 5a, 6a, 7a and 7b were obtained in 13 to 15 step sequences with overall yields of up to 12%. The routes diverged from a common precursor aldehyde 11, which had been prepared in 18% yield over 11 steps, and had exploited the Yamamoto asymmetric carbocyclization and MgBr2-mediated Sakurai reaction to

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

• ) to give the desired cyclized product 12. Structure of senaequidolide (13) and ellipticine (14). Gold(I)-catalyzed carbocyclization. Proposed mechanism for the gold(I)-catalyzed cyclization. Gold-catalyzed 5-exo-dig carbocyclization cascade. Supporting Information Supporting Information File 498

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

• . Experimental General procedure for the gold-catalyzed carbocyclization General procedure for the the gold(I)-catalyzed carbocyclization of vinylallenyl acetal: A two-necked flask was charged with chloro(triphenylphosphine)gold(I) (11.1 mg, 0.022 mmol) and silver triflate (5.8 mg, 0.022 mmol), and to this

• silica bed. The solvent was evaporated under reduced pressure. The crude product was eluted through a short silica column (3% ethyl acetate in hexane) to afford the desired ketone 4a (70.6 mg, 0.40 mmol, 89%) as a pale yellow oil. General procedure for the gold(I)-catalyzed carbocyclization of

• acetate 5a. Catalyst screening over various acid catalysts. Gold-catalyzed cyclization of allenyl acetals. Gold-catalyzed carbocyclization of propargylic esters. Supporting Information Supporting Information File 308: Experimental details. Acknowledgements We thank the National Science Council, Taiwan

Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

• Fabrice Chemla,
• Florian Dulong,
• Franck Ferreira and
• Alejandro Pérez-Luna

Beilstein J. Org. Chem. 2013, 9, 236–245, doi:10.3762/bjoc.9.28

• plausible explanation for the fact that bromine substitution occurs from α-oxgenated bromoalkyne 11 and not from 9. Regarding our 1,4 addition/carbocyclization sequence, these test experiments provide two important pieces of evidence for the behavior of 3a in the presence of a dialkylzinc. First, β-alkoxy

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Cyclization of 5-hexynoic acid to 3-alkoxy-2-cyclohexenones

• Anne T. Hylden,
• Eric J. Uzelac,
• Zeljko Ostojic,
• Ting-Ting Wu,
• Keely L. Sacry,
• Krista L. Sacry,
• Lin Xi and
• T. Nicholas Jones

Beilstein J. Org. Chem. 2011, 7, 1323–1326, doi:10.3762/bjoc.7.155

• under a variety of conditions [5][6]. We report herein the cyclization of 5-hexynoyl chloride (2) as a complementary approach to the synthesis of 3-alkoxy-2-cyclohexenones 1 (Scheme 1). The carbocyclization of 5-hexynoic acid was first reported by Tedder in 1957 [7]. Treatment of 5-hexynoic acid with

One-pot Diels–Alder cycloaddition/gold(I)-catalyzed 6-endo-dig cyclization for the synthesis of the complex bicyclo[3.3.1]alkenone framework

• Boubacar Sow,
• Gabriel Bellavance,
• Francis Barabé and
• Louis Barriault

Beilstein J. Org. Chem. 2011, 7, 1007–1013, doi:10.3762/bjoc.7.114

• represents a significant synthetic challenge. This type of architectural feature is embedded in various complex biologically active compounds such as hyperforin and garsubellin A. Herein, we report a highly diastereoselective one-pot Diels–Alder reaction/Au(I)-catalyzed carbocyclization to generate bicyclo

• [3.3.1]alkanones in yields ranging from 48–93%. Keywords: bicyclo[3.3.1]nonenone; carbocyclization; Diels–Alder; gold catalysis; one-pot process; Introduction Highly oxygenated and densely substituted carbon-bridged medium sized rings such as 1 are commonly found in nature as structural frameworks of

• generate carbon-bridged frameworks of various sizes through a gold(I)-catalyzed carbocyclization [13]. Although the cyclization of enol ether 5 can produce 5-exo and 6-endo products, we found that gold complexes 6, having bulky phosphine ligands such as 2-bis(tert-butylphosphino)biphenyl, gave exclusively

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

• cationic Au(I) complexes are the most efficient catalysts for the intramolecular coupling of allyl acetates with allylstannanes (compound 227) [129]. Zhu and co-workers reported a gold-catalyzed carbocyclization of dienyl acetates 229 to construct multi-functionalized 3-vinylcyclohexanol derivatives 230

When gold can do what iodine cannot do: A critical comparison

• Sara Hummel and
• Stefan F. Kirsch

Beilstein J. Org. Chem. 2011, 7, 847–859, doi:10.3762/bjoc.7.97

• ) activated by AgSbF6 (Scheme 7) [91]. A 1,5-enyne disubstituted at the terminal carbon of the alkene (e.g., 19) leads to a very selective 5-endo carbocyclization where no side products resulting from 5-exo or 6-endo modes were observed. A mechanism was proposed involving a cationic intermediate after

• alkynes. For example, Toste and co-workers investigated the previously unreported 5-endo carbocyclization of 43 which involves the cyclization of ß-keto esters onto non-terminal alkynes by use of gold catalysts (Scheme 13) [105], where traditional transition metal-catalyzed Conia-ene type cyclizations are

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• key step is the syn addition of the tin cuprate to the acetylene, which controls the cis stereochemistry required for cyclization. [23] Seven Membered Carbocycles The use of nitriles and imines as electrophiles in the silylcupration of allene provides new alternatives for carbocyclization. Recently