Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• ; indanones; trichloromethyl group; triflic acid; Introduction Superelectrophilic activation of organic compounds under the action of strong Brønsted and Lewis acids is an effective method for the synthesis of various carbocycles and heterocycles, and polyfunctional compounds (see books [1][2] and reviews [3

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• the bi(hetero)arene–Pd(II) species 177 which undergoes reductive elimination furnishing the desired products 174/175. C–H Annulation of pyridine to fused heterocycles Annulation reactions in organic synthesis have achieved great attention toward the construction of various carbocycles and heterocycles

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• aryl donors [11][12][13][14][15][16]. Their cyclic derivatives have a proven utility as precursors for the synthesis of hetero- and carbocycles [17][18][19][20][21], and their pronounced σ-holes [22] render them efficient halogen-bond donors (XB donors in XB catalysis) [23]. Despite their great

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• reactions constitutes one of the main pillars of organic synthesis [1]. In this respect, the all-carbon Nazarov cyclization of divinyl ketones represents a direct method for the synthesis of five-membered carbocycles [2][3][4][5][6][7][8][9]. Variants of the Nazarov cyclization with substrates bearing one

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

• diterpenoids all share the same tetracyclic skeleton, with 5, 7, 6 and 5-membered carbocycles commonly named A, B, C and D (Figure 1). The diversity in this family arises from different oxidation states at positions 2, 3, 5, 6, 7, 10, 14, 15, 16, and 17 which can bear free, acylated or glycosylated alcohol

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

• -substituted β-diketones 2a and 2b (61 and 70% yield, respectively). Notably, the unsaturated carbocycles expected from palladium β-hydride elimination were not observed, indicating that an oxidant was not required in the reaction medium to regenerate the Pd(II) species. Later, deuterium-labeling experiments

• isomerization protocol triggered by an MHAT process using salen cobalt complexes as catalysts to furnish isomerized and cycloisomerized products (Scheme 19) [72]. Five and six-membered carbocycles containing quaternary carbon centers were synthetized in good to excellent yields and with excellent

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• -radical cascade reactions could efficiently construct various carbocycles and heterocycles with multifarious structures and complexity [59][60][61]. Centered on this context, we give a clear overview on a variety of novel cyclization reactions initiated by EDA complexes from the recent years. In 2016

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• compounds as binucleophiles for the construction of various carbocycles, heterocycles as well as in asymmetric catalysis [44][45][46][47][48][49][50]. Our initial objective to trap the aza vinyl rhodium carbenoid using 1,3-dicarbonyl compounds to form pyrazolone was unsuccessful which instead led to the

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• , stereo-congested, five-membered carbocycles containing all-carbon quaternary center(s) is, at present, a distinct challenge in modern synthetic chemistry, which can be accessed through the all-carbon [3 + 2] cycloaddition. More importantly, the all-carbon [3 + 2] cycloaddition can forge vicinal all

• , biologically important natural products [1][2][3][4][5][6][7] (Figure 1). Meanwhile, the construction of quaternary carbon stereocenter(s) is, at present, a distinct challenge in modern synthetic chemistry [8][9][10][11]. Therefore, the synthesis of highly-substituted five-membered carbocycles bearing

• , the all-carbon [3 + 2] cycloaddition can forge vicinal all-carbon quaternary centers [12] in a single-step operation and provides a direct access to various substituted five-membered carbocycles. These characteristics make the all-carbon [3 + 2] cycloaddition an appealing method and/or strategy in the

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• even anthracene. At higher temperature, the cycloadducts undergo an intramolecular SE(Ar) reaction leading to condensed carbocycles incorporating a 1-(trifluoromethyl)-1-(dimethylamine)indene ring system. With styrenes and some substituted styrenes, cascade reactions take place, which likely include

• consider the reactivity of the electrophilic (“electron-poor”) acetylenic bond toward 1,3-dienes, and show how the expected [4 + 2] or [2 + 2] cycloaddition products can enter subsequent cascade reactions toward carbocycles which incorporate a C(CF3)NMe2 structural unit. Results and Discussion The Diels

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• highly strained structure and bonding properties of cyclopropyl rings have constantly fascinated successive generations of chemists. These small carbocycles are known to have high ring strain (27.5 kcal/mol) and limited degrees of freedom, making them very attractive substrates for various chemical

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• involving cyclopropenes, which are largely dominated by ring-cleavage processes to access functionalized acyclic compounds or to construct new carbocycles or heterocycles, those reactions that preserve the three-membered ring and enable access to diversely substituted cyclopropanes or

• ]. Alkylidenecyclopropanes also constitute another important class of strained carbocycles displaying a versatile chemistry owing to their multiple reactive sites (the exocyclic olefin and the proximal and distal bonds on the ring) [10][11][12][13][14][15]. Although the synthesis of alkylidenecyclopropanes can be achieved

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• allows sigmatropic rearrangements leading to odd-numbered carbocyclic derivatives [8]. In this sense, seven-membered carbocycles, namely 1,4-cycloheptadienes, can be forthrightly prepared from cis- or trans-1,2-divinylcyclopropanes through a Cope rearrangement [8][9]. The potential of this type of

Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

• Ritabrata Datta and
• Subrata Ghosh

Beilstein J. Org. Chem. 2018, 14, 2708–2714, doi:10.3762/bjoc.14.248

• ] of norbornene derivatives with a suitably located alkynyl side-chain on the nucleus (path 2, Scheme 1) to form carbocycles has been less explored. The greatest advantage of this protocol lies in its potential in increasing the molecular complexity through Diels–Alder reaction of the resulting ring

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• summarized various approaches to a wide range of carbocycles and heterocycles that deals with a strategic utilization of SM coupling and metathesis as key steps. Interestingly, application of these two powerful methods in combination for a C–C bond formation process shorten the synthesis sequence for the

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• ; dibenzotropone; halobenzotropolone; halobenzotropone; tribenzotropone; tropone; Review 1. Introduction Tropone (1) and tropolone (2) have fascinated organic chemists for well over one hundred years. The carbocycles 1 and 2 are a special variety of organic compounds and represent a nonbenzenoid type of aromatic

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• synthetic protocol was also amenable to the multigram preparation of these promising molecules, which may contribute significantly to the development of novel negative-type LC molecules containing CF2CF2 carbocycles. Keywords: gram-scale preparation; liquid crystals; short-step preparation

• achieved. The present synthetic protocol is promising for the development of a wide range of negative-type LC molecules containing CF2CF2 carbocycles by the selection of the starting Grignard reagent and should contribute to further evolution of VA-type LC display molecules. Typical examples of previously

• for multicyclic mesogens 1 and 2. Short-step approach to CF2CF2-containing carbocycles. Mechanism for the reaction of γ-keto ester 6 with vinyl Grignard reagents. First multigram-scale preparation of CF2CF2-containing multicyclic mesogens. Stereochemical assignment of the ring-closing metathesis

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• -membered carbocycles bearing a difluoroiodomethyl group. In contrast, 2-(3,3-difluoroallyl)biaryls underwent a similar cyclization at the α-carbon atoms to afford ring-difluorinated seven-membered carbocycles. Keywords: alkenes; carbocycles; cyclization; electrophilic activation; fluorine; iodine

• carbocycles that are promising candidates for pharmaceuticals, agrochemicals, and functional materials. In contrast, the cationic cyclization of 1,1-difluoro-1-alkenes using electrophilic reagents (under acidic conditions) has been quite limited because of their low electron densities caused by fluorine

• synthesis. We have already achieved the metal-catalyzed and acid-mediated cationic cyclization of 1,1-difluoro-1-alkenes. In the former case, we reported the palladium [6][7][8][9][10], indium [10][11][12][13], and silver-catalyzed construction of ring-fluorinated carbocycles and heterocycles [14]. In the

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• substituted carbocycles [119][120]. An example in described in Scheme 22. The 5-membered ring is formed via a K2CO3 mediated SN2 – conjugate addition sequence between malononitrile and 6-bromo-2-hexenoate derivatives 67a,b. Dicyanocyclopentanes 68a,b are treated with tributyltin hydride/AIBN giving the

Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction

• Salvatore V. Giofrè,
• Santa Cirmi,
• Raffaella Mancuso,
• Francesco Nicolò,
• Giuseppe Lanza,
• Laura Legnani,
• Agata Campisi,
• Maria A. Chiacchio,
• Michele Navarra,
• Bartolo Gabriele and
• Roberto Romeo

Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278

• , Universities, and Research (MIUR: PRIN 2010-2011, 20109Z2XRJ_007), the Universities of Messina, Catania and Calabria, Interuniversity Research Centre on Pericyclic Reactions and Synthesis of Hetero and Carbocycles Systems and the Interuniversity Consortium for Innovative Methodologies and Processes for

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• as catalysts, high site-selectivity is generally achievable, which makes this type of reaction a valuable tool for the construction of carbocycles from readily available starting materials [1][2][3][4][5][6]. While most of the site-selective metal–carbene C(sp3)–H bond insertions are based on

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• generated from the tetracyclic triazolium salt 53 gave the best results [50]. It is noteworthy that the absolute stereochemistry of the α-carbonyl quaternary center of benzo-fused carbocycles and chromanones is installed with excellent control (Scheme 33). A combination of D-camphor-derived triazolium

A concise and efficient synthesis of benzimidazo[1,2-c]quinazolines through CuI-catalyzed intramolecular N-arylations

• Xinlong Pang,
• Chao Chen,
• Ming Li and
• Chanjuan Xi

Beilstein J. Org. Chem. 2015, 11, 2365–2369, doi:10.3762/bjoc.11.258

• -cyanoaniline (1) and diaryliodonium salts 2 based on our previously published method [13][14] (Scheme 1). Results and Discussion During the study of the synthesis of various carbocycles or heterocycles with copper catalysts [13][14][15][16][17], we found an interesting tandem reaction of o-cyanoanilines 1 and

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• carbocycles by employing the RRM protocol starting with appropriate norbornene derivatives [43]. Recently, Kotha and Ravikumar [44] have found a new route to various polycyclic compounds by employing the DA reaction and the RRM protocol as key steps. To this end, the key building block 202 has been prepared

• approach toward C3-symmetric chiral trimethylsumanene 209. Triquinane synthesis via IMDA reaction and RRM protocol. RRM approach to polycyclic compounds. RRM strategy toward cis-fused bicyclo[3.3.0]carbocycles. RRM protocol towards the synthesis of bicyclic lactone 230. RRM approach to spiro heterocyclic

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• such ruthenium complexes often contain coordinated aromatic carbocycles [27][28][29]. In contrast, only a few examples Ru(II) complexes of functionalized NHCs containing easily dissociating acetonitrile ligands have been studied [30][31][32]. We have reported the synthesis of some pyridine- and