The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• organocatalysts ((thio)ureas, squaramides, quinolinium thioamide, etc.) in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel–Crafts alkylation, Michael addition, Diels–Alder and aza-Henry reactions. However, the 1,2-aminoindanol core

• acting through hydrogen bonding, such as thiourea, urea, squaramide, and thioamide frameworks. These have been efficiently employed in a few organocatalytic processes such as Friedel–Crafts alkylations, Michael additions, Diels–Alder reactions and aza-Henry reactions, as discussed below. Friedel–Crafts

• derivative 4 to develop the first organocatalytic enantioselective Friedel–Crafts (F–C) alkylation of indoles, employing nitroalkenes as versatile electrophiles. In the presence of catalyst 4, the differently functionalized indole derivatives 2 reacted with aryl and alkyl nitroalkenes 3 in dichloromethane at

Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes

• H. Surya Prakash Rao and
• A. Veera Bhadra Rao

Beilstein J. Org. Chem. 2016, 12, 496–504, doi:10.3762/bjoc.12.49

• flavanoid bearing the triarylmethane motif [31][32]. Triarylmethanes are typically synthesized by a Friedel–Crafts-type substitution of the three alkoxy groups in a trialkyl orthoformate (Scheme 1A, method 1) [33][34][35] or by sequential two-step addition of electron-rich aromatic nucleophiles to activated

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• Mannich–Michael pathway instead of the more “reasonable” Michael–Mannich pathway. In 2012, Wang and co-workers reported a novel domino Friedel–Crafts alkylation (via conjugate addition)-hemiacetalization catalyzed by rosin-derived tertiary amine-thiourea 187 (Scheme 61) [82]. Reagent 87 was successfully

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• the two enantiomers of 32 will react more rapidly with nitromethane in the presence of the cupreidine catalyst CPD-33. As these enantiomers equilibrate via 35 in the presence of the catalyst, a dynamic kinetic asymmetric reaction occurs (Scheme 9b). Friedel–Crafts reaction Pedro and co-workers have

• utilized a 9-OH benzoyl derivatised cupreine CPN-38 to effect a Friedel-Crafts reaction of 2-naphthols 36 with benzoxathiazine 2,2-dioxides 37 (Scheme 10). These cyclic imides, derived from salicylic aldehydes, have a rigid structure which prevents E/Z-isomerization, allowing for greater control over the

• . A cupreidine derived catalyst induces a dynamic kinetic asymmetric transformation. Cupreine derivative 38 has been used in an organocatalytic asymmetric Friedel–Crafts reaction. Examples of 6’-OH cinchona alkaloid catalyzed processes include: (a) Deng’s addition of dimethyl malonate into

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• reduction, and intramolecular Friedel–Crafts reaction [29][30] (Scheme 2). In particular, the reaction of pyranosides bearing acetyl substituents on the carbamate groups showed complete anomerization [32]. We expected that anomerization via endocyclic cleavage would be useful for mycothiol synthesis

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• also investigated (vide infra), but did not produce satisfactory results. Settambolo et al. [20] reported a synthetic route starting from an acylation of pyrrole by phenylacetyl chloride via a Friedel–Crafts reaction, followed by reduction by NaBH4, and elimination to give the vinylpyrrole product

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• , Stefana Żeromskiego116, 90-924 Łódź, Poland University of Warsaw, Biological and Chemical Research Center, Żwirki i Wigury 101, 02-089 Warszawa, Poland PPSM, ENS Cachan, CNRS, UniverSud, 61 av President Wilson, 94230 Cachan, France 10.3762/bjoc.11.266 Abstract Friedel–Crafts-type reaction of pyrene with

• = 0.25) was assigned to π–π aggregates, the presence of which was revealed by single-crystal X-ray diffraction analysis. Keywords: amide; fluorescence; isothiocyanate; phosphonate; pyrene; thioamide; X-ray structure; Introduction Friedel–Crafts-type reaction of arenes with isothiocyanates constitutes a

• amidophosphonates 3a–d in 87–94% isolated yield (Scheme 1). Therefore, the indirect route to these compounds described above proved very efficient. We did not attempt to prepare 3a–d via direct Friedel–Crafts-type reaction of pyrene with (isocyanato)alkyl phosphonates because these compounds are difficult to

Efficient synthetic protocols for the preparation of common N-heterocyclic carbene precursors

• Morgan Hans,
• Jan Lorkowski,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2015, 11, 2318–2325, doi:10.3762/bjoc.11.252

• and ZnCl2. This Friedel–Crafts alkylation was carried out under solvent-free conditions and afforded high yields of the bulky aniline needed to follow the Arduengo formylative cyclization path. It was originally performed in a sealed tube under autogeneous pressure at 160 °C. We checked that the

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

• Iris Binyamin,
• Shoval Meidan-Shani and
• Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

• : (A) Attack by nucleophilic low valent phosphorus compounds (P(III) or phosphide ions P(II)) on positively charged carbon centers (e.g., Michaelis–Arbuzov [7], Michaelis–Becker [8], Pudovik [9], Friedel–Crafts reactions [10], catalytic hydrophosphorylation [11] and others). Notably, these reactions

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• order to avoid downstream incompatibilities. The initial step was a Friedel–Crafts acylation of isobutylbenzene (10) with propionic acid (11) in the presence of excess triflic acid (12). The transformation was found to work very effectively and the acid catalyst was also tolerated in the subsequent 1,2

• (Friedel–Crafts acylation, 1,2-aryl migration and saponification) this report focuses on improved output by intensifying the overall sequence (Scheme 3). As such an in-line extraction is performed after the Friedel–Crafts acylation step, followed by dissolving intermediate 18 in trimethyl orthoformate and

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• a glycoluril-based framework possessing quinone moieties for developing a Diels–Alder cycloaddition strategy. Thus compound 12 [33] was prepared in 73% yield by treatment with an excess of hydroquinone in 1,2-dichloroethane using a Friedel–Crafts alkylation as an electrophilic aromatic substitution

DBU-promoted carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone

• Wen-Zhen Zhang,
• Si Liu and
• Xiao-Bing Lu

Beilstein J. Org. Chem. 2015, 11, 906–912, doi:10.3762/bjoc.11.102

• [4]. Roquinimex was reported as an antineoplastic agent [5]. Traditional methods for accessing these compounds rely heavily on cyclization reactions using diethyl carbonate in the presence of inorganic bases [6][7] or Friedel–Crafts reactions using strong and corrosive acids [8]. In terms of

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• tested in the asymmetric Friedel–Crafts alkylation of N-methylpyrrole with α,β-unsaturated aldehydes. A variety of substituted enals was investigated to explore the activity of the catalytic system which was also compared with monovalent analogues. The catalyst 4b showed excellent turnover rates and no

• loss of activity due to immobilization, albeit moderate enantioselectivities were observed. Moreover, easy recovery by selective precipitation allowed the reuse of the catalyst for three cycles. Keywords: Friedel–Crafts; homogeneous catalysis; hyperbranched polyglycerol; imidazolidin-4-one

• support in asymmetric organocatalysis. The use of chiral imidazolidinones in organocatalysis has been extensively reported for a wide range of enantioselective reactions involving α,β-unsaturated aldehydes, such as the Diels–Alder reactions [50], 1,3-dipolar cycloadditions [51] and Friedel–Crafts

TTFs nonsymmetrically fused with alkylthiophenic moieties

• Rafaela A. L. Silva,
• Bruno J. C. Vieira,
• Marta M. Andrade,
• Isabel C. Santos,
• Sandra Rabaça,
• Dulce Belo and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

• between compounds III and IV, respectively, following a general procedure for non-symmetrically substituted TTFs [13] as first described by Underhill and co-workers [14] (Scheme 2). 5-(tert-Butyl)thieno[2,3-d][1,3]dithiol-2-one (I) was prepared by a low temperature Friedel–Crafts alkylation of 5,6-thieno

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

• Henok H. Kinfe,
• Fanuel M. Mebrahtu,
• Mandlenkosi M. Manana,
• Kagiso Madumo and
• Mokela S. Sokamisa

Beilstein J. Org. Chem. 2015, 11, 583–588, doi:10.3762/bjoc.11.64

• their profound biological importance, there are different routes reported for their synthesis but the common ones are: nucleophilic substitution of an activated glycosyl donor with organometallic aryl derivatives, cross-coupling of aryls with glycals, Friedel–Crafts arylation at the anomeric centre of

Natural phenolic metabolites with anti-angiogenic properties – a review from the chemical point of view

• Qiu Sun,
• Jörg Heilmann and
• Burkhard König

Beilstein J. Org. Chem. 2015, 11, 249–264, doi:10.3762/bjoc.11.28

•  7). Compounds 30–34 were obtained through Friedel–Crafts acylation of 29 with corresponding acyl chlorides in 55–81% yield. Subsequent alkylation with geranyl bromide gave products 35–39 in moderate yields from 55 to 60%. Finally, p-toluenesulfonic acid (pTSA)-catalyzed cyclization afforded the

• target compounds 40 and 41 in 53 and 65% yield, respectively. The synthesis of the second series is shown in Scheme 8 [59]. Amberlyst 15 efficiently catalyzed the condensation of 1,3,5-trihydroxybenzene (29) with isoprene in 53% yield. The following Friedel–Crafts acylation gave the intermediates 43–46

• inhibited angiogenic processes in various in vitro and in vivo models [82][83]. The typical synthesis of genistein starts from 1,3,5-trihydroxybenzene (29, Scheme 10) [84]. After the Houben–Hoesch reaction or Friedel–Crafts acylation, the cyclization of the resulting hydroxyketone 59 in the presence of BF3

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• the halonium source. Several reactions using bromonium- and iodonium cations such as iodo-etherification, lactonisation or Friedel–Crafts alkylation reactions can be found in literature. However, these procedures often use expensive or toxic halonium sources like molecular bromine [10][28][29] or

Redox active dendronized polystyrenes equipped with peripheral triarylamines

• Toshiki Nokami,
• Naoki Musya,
• Tatsuya Morofuji,
• Keiji Takeda,
• Masahiro Takumi,
• Akihiro Shimizu and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2014, 10, 3097–3103, doi:10.3762/bjoc.10.326

•  2. Di(p-bromophenyl)carbinol (1) was treated with SOCl2 to obtain di(p-bromophenyl)methyl chloride (2) in quantitative yield. A Friedel–Crafts-type alkylation [29] of diphenylsilane 3 with 2 in the presence of boron trifluoride etherate as a Lewis acid gave 4 in 86% yield. The oxidation potential of

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• -acyliminium ion pool and under Friedel–Crafts conditions mono-alkylation products are formed (Scheme 8) [43][44]. A problem with conventional Friedel–Crafts alkylation is the mono-alkylated product is more reactive than the starting material making di- and tri-alkylation products more likely. Improved yields

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• fluoride ion under formation of an S–F bond. Radical 49 is then further oxidized to the corresponding cationic species 50, which undergoes elimination of HF under formation of cationic intermediate 51. Finally, intramolecular trapping by the aromatic ring in a Friedel–Crafts type reaction leads to

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• synthesis of a furan-based analogue of thiamine. This analogue was converted to its diphosphate, which is another extremely potent inhibitor of ZmPDC, and could also be functionalised at the 2-position using a Friedel–Crafts acylation. Results and Discussion Synthesis of ThDP analogue 17 The key step in our

• strong inhibitor of ZmPDC with picomolar affinity. Friedel–Crafts acetylation of the furan at C-2 was successful which opens the possibility of synthesising furan analogues of the enzymic reaction intermediates. Structure of thiamine diphosphate (ThDP, 1). Time course inactivation of ZmPDC by various

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• -di-tert-butyl-4-methylphenol) improved the yields of methylenenortricyclenes. A complete deuterium incorporation was observed in the superoxide-mediated reaction in DMSO-d6. Friedel–Crafts acylation reactions of 3-methylenenorticyclenes yielded 2-propanone-substituted pentachloronorbornenes

• . Keywords: BHT; dehydrohalogenation/rearrangement; Friedel–Crafts acylation; methylenenortricyclene; superoxide ion; Introduction The chemistry of the superoxide ion (O2−·) has been a subject of growing interest because of its presence in all aerobic organisms as a respiratory intermediate [1][2][3][4][5

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• Kitamura gave tetrahalide 12 in good yield on >10 g scale [25]. Suzuki cross-coupling with 12 furnished p-terphenyl 14, followed by oxidation of the methyl groups to produce diacid 15. Intramolecular Friedel–Crafts acylation then afforded 5,11-dibromo-IF-dione 11. The yields for the Sonogashira cross

• . Black lines represent the molecules with circles denoting the centroid. Transannular cyclization route to diethynyl-IF-diones 8. Suzuki/Friedel-Crafts route to diethynyl-IF-diones 8. Diethynyl-IF-diones synthesized and yields for Sonogashira cross-coupling. Electrochemical and optical data for ID-diones

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• with Friedel–Crafts acylation of 1-methoxynaphthalene (11) yielding 1-acetyl-4-methoxynaphthalene (12, 73%). α-Bromination with copper(II) bromide gave 13 (44%) which was converted to the phosphate ester using tetramethylammonium diethyl phosphate in dimethoxyethane (DME) at room temperature to give

• ) and comparison with an independently synthesized sample obtained from Friedel–Crafts alkylation of 1-methoxynaphthalene (11) with methyl bromoacetate and ferric oxide [27]. Quantum yields for disappearance and percentage conversions for 14a are higher than that of 14b as indicated in Table 1. After