Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• ). This reaction has been successfully used for common amines using acetic acid and water, but benzylamines and benzamides show no reaction under aqueous conditions. In the case of amino acid ester hydrochlorides, the reaction to give pyrrole can be carried out without the need for the two-phase

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• synthesis of synthetically useful N-arylsulfonylimines from N-(arylsulfonyl)benzylamines using K2S2O8 in the presence of pyridine as a base is reported herein. In addition, a “one-pot” tandem synthesis of pharmaceutically relevant N-heterocycles by the reaction of N-arylsulfonylimines, generated in situ

• -aryl(benzyl)amines to N-arylimines using K2S2O8 is reported to be problematic, the oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines using K2S2O8 has been achieved for the first time. The dual role of the sulfate radical anion (SO4·−), including hydrogen atom abstraction (HAT) and

• in nature. To overcome these limitations, oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines, as opposed to the traditional methods, under mild and neutral reaction conditions has been reported, although limited to a few methods. However, these methods of oxidation involving the use of

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• different benzylamines (1:1:2.2) (Table 2, entry 7). The reaction was carried out in tert-amyl alcohol (TAA), which led to product 10 in 55% yield and 99% conversion of 17 [55]. In addition to hydrogen peroxide, other oxidizing agents can be used in the synthesis of menadione (10) from 17 and include

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• . Benzylamines and derivatives thereof have been described in literature to be susceptible to oxidation by diverse reagents (tritylium ion [40], silver [38] and cerium salts [41], peroxides [42][43][44] and persulfates [45], nitroxyls [46], hypervalent iodine compounds [39][47], or tetrahalomethanes [48]) to

• nitrogen-containing investigated precursors only primary and secondary benzylamines (see 2a and 2b), giving fluorenone (3) in yields of 62% and 60%, respectively, are suitable functional groups for the TBHP-mediated oxidative cyclization to give fluorenones. These yields are comparable to those previously

• , TBHP-mediated radical cyclization is applicable to a wide variety of primary and secondary benzylamines bearing electron-donating and electron-withdrawing groups to synthesize fluorenones in poor to good yields, and utilized this method for the first total synthesis of the fluorenone natural product

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• reaction of 2-trifluoromethyl-1,3-enynes 36 with aliphatic primary amines and the following NXS-mediated oxidative cyclization (Scheme 13) [57]. The method tolerated various substituted benzylamines, 2-phenylethanamines, isopropylamine, and other aliphatic chain-like amines. Furthermore, both furan-2

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• ] tailored a microwave-assisted multicomponent reaction for fast and efficient generation of diastereoselective dibenzo[c,e]azepinones. The protocol utilized substituted 2'-formylbiphenyl-2-carboxylic acid 19, benzylamines 20, and isocyanides 21 in TFE and Na2SO4 as drying agent for the construction of

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• . As can be seen from Scheme 2 the yields of the amination products 5 and 6 were dependent on the nature of the amine as well as on the used phthalazinone. Efficient results of coupling were received using, inter alia, cyclic, aromatic or benzylamines. The reaction of 3a with piperidine gave a higher

• -amine (5f, 80%), cyclohexylamine (5d, 85%), and also with the 4-CF3 and 4-OMe-benzylamines (5g, 85%; 5h, 65%). Additionally, when using primary amines in the reaction the formation of polysubstituted products was not observed. On the other hand, N-phenylpyridin-2-amine afforded the appropriate compound

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

• lithium acetylides [25]. By a photoredox-catalytic process, primary α-(trifluoromethyl)-α-(4-pyridyl)benzylamines were obtained from α-(trifluoromethyl)-benzaldoximes and 4-cyanopyridine [26]. We have recently introduced a new class of acetylenic iminium salts, namely 1-(trifluoromethyl)prop-2-yn-1

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• semicontinuous process was reported for the synthesis of racemic fluorinated phenylalanine·HCl starting from benzylamines 47a–c. Thus, a singlet oxygen-driven photooxidative cyanation of amines 47a–c using tetraphenylporphyrin (Tpp), followed by an acid-mediated hydrolysis of the intermediate fluorinated α-amino

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• hydride-mediated reaction of arylmethyl isocyanides with xanthate esters in DMF is reported. The products thus obtained were compared with the carbamothioates obtained by the sodium hydride-mediated condensation of the corresponding benzylamines and xanthate esters in DMF. To account for these unexpected

• reactions, a mechanism is proposed in which the key steps are supported by quantum chemical calculations. Keywords: benzylamines; carbamothioates; density functional theory; intrinsic reaction coordinate analysis; isocyanides; sodium hydride; xanthate esters; Introduction Carbamothioates (thiocarbamates

• undergone a reductive cleavage to give the corresponding benzylamines, which might have reacted with 1 to give 4. A control experiment was therefore conducted with only the isocyanide under standard reaction conditions. Only unchanged isocyanide was found under these conditions, thus ruling out this initial

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

• Hoang Huy Do,
• Saif Ullah,
• Alexander Villinger,
• Joanna Lecka,
• Jean Sévigny,
• Peter Ehlers,
• Jamshed Iqbal and
• Peter Langer

Beilstein J. Org. Chem. 2019, 15, 2830–2839, doi:10.3762/bjoc.15.276

• anilines as reagents, we also successfully employed alkyl- and benzylamines which required an additional optimization of the conditions and the employment of different ligands. Therefore, we feel that our approach is more general and merits publication. In addition to the synthetic work, we report, for the

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• 2015, Zhao et al. [60] discovered a Pd(II)-catalyzed ortho-selective C–H fluorination of oxalyl amide-protected benzylamines (Scheme 22). The yields were up to 95% with NFSI as the [F+] source and tert-amyl alcohol as the solvent. In 2018, the Sorensen group [61] described a direct Pd-catalyzed ortho-C

• reagent. Notably, Cu(II) salts were crucial for forming the aryl–CF3 bonds. In Yu’s study, benzamides and benzylamines were well trifluoromethylated via a Pd(II)/Pd(IV) catalytic cycle with the addition of TFA (and Ag2O) (Scheme 66a). With an acetamido group as a directing group, Shi developed an

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• functional group tolerance, broad substrate scope and operational simplicity are the prominent advantages of the current protocol. Keywords: amidation; benzoylation; benzylamines; pyridinium salt of phenacyl bromides; Introduction Amidation and esterification are fundamental transformations in synthetic

• -workers also demonstrated a transition metal-free aerobic oxidative cleavage of C–C bonds of phenacyl azides employed in the construction of amides utilizing benzylamines [41]. Herein we wish to report a metal-free C(CO)–C(α) bond cleavage of pyridinium salts of phenacyl bromides for the facile synthesis

• of amides and esters in the presence of a suitable amine or alcohol under basic conditions (Scheme 1). To the best of our knowledge, this is the first report for the synthesis of amides and esters from the pyridinium salts of phenacyl bromides and benzylamines/alcohols via C(CO)–C(α) bond cleavage

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• 2-benzoylpyridine (145) and different benzylamines was carried out to synthesize 1,3-diarylated imidazo[1,5-a]pyridines (Scheme 50). The reaction took place under aerobic conditions utilizing Cu-MOF-74 as a catalyst [130]. The reaction was unprecedented in terms of oxidative amination of C(sp3)–H

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• in Supporting Information File 1). Despite a considerable scope for varying substituents at the nitrogen atom in styrenes 4 and 5, the developed procedures (Scheme 1 and Scheme 2) do not allow one to obtain benzylamines with a secondary nitrogen atom. The approach outlined in Scheme 3 makes it

Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline

• Benedikt C. Melzer,
• Jan G. Felber and
• Franz Bracher

Beilstein J. Org. Chem. 2018, 14, 130–134, doi:10.3762/bjoc.14.8

• moiety of 5 is resistant to hydrogenolysis, whereas the benzyl ether is readily removed. This order of reactivity is known from previous work [22]. Since it is further known that quaternary benzylammonium compounds undergo hydrogenolysis easier than the corresponding tertiary benzylamines [22], we

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• bond synthesis under ball-milling conditions. Cross dehydrogenative coupling reactions between benzaldehydes and benzylamines were performed in presence of phenyliodine diacetate (PIDA) using the acid salt NaHSO4 [81]. The highly exergonic reaction (contact explosive) of acidic iodine(III) and basic

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• were isolated in quantitative yields. The amination reaction was then performed on a number of substrates, ranging from simple mono- and disubstituted anilines, benzylamines and polyaromatic amines such as anthracene-, phenanthrene-, pyrene- and crysenamine (Scheme 12). An interesting feature of LAG

Mechanochemical N-alkylation of imides

• Anamarija Briš,
• Mateja Đud and
• Davor Margetić

Beilstein J. Org. Chem. 2017, 13, 1745–1752, doi:10.3762/bjoc.13.169

• hazardous hydrazine hydrate was replaced by 1,2-diaminoethane [39] and conversion to the corresponding benzylamines was quantitative within 1 h. As a proof of concept of reaction, p-methylbenzylamine was isolated in 41% yield in the form of acetamide 42. In this way, a three-step, two-pot (A and B, Scheme 5

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• process (Scheme 21). During their efforts in developing cascade reactions for the synthesis of heterocycles, Fu and co-workers [77] established a method for the synthesis of quinazolinones 84 through the reactions between o-halobenzamides 82 and benzylamines 83. The formation of the target products were

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• by reacting thiobenzoic acid, isocyanoacetate, two aliphatic aldehydes (iPr, t-Bu) and benzylamines/ammonia in either methanol (for benzylamines) or trifluoroethanol (for ammonia) [108]. Then, subsequent hydrolysis of the methylester followed by activation via acid chlorides or triflates gave the 5

Diversity-oriented synthesis of dihydrobenzoxazepinones by coupling the Ugi multicomponent reaction with a Mitsunobu cyclization

• Lisa Moni,
• Luca Banfi,
• Andrea Basso,
• Alice Brambilla and
• Renata Riva

Beilstein J. Org. Chem. 2014, 10, 209–212, doi:10.3762/bjoc.10.16

• reaction of an ortho-(benzyloxy)benzylamine, glycolic acid, an isocyanide and an aldehyde, followed by an intramolecular Mitsunobu substitution was developed. The required ortho-(benzyloxy)benzylamines have been in situ generated from the corresponding azides, in turn prepared in high yields from salicylic

• because of interference of the phenol moiety, which can act as internal nucleophile. For these reasons we decided to use the O-benzylated benzylamines as starting materials for the U-4CR, postponing the hydrogenolytic removal of the protecting group after the condensation. Four different benzyl azides 2a

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

• Nan Sun,
• Bin Li,
• Jianping Shao,
• Weimin Mo,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2012, 8, 61–70, doi:10.3762/bjoc.8.6

• time. This rate difference could be originated from the different basicities and their differences in water solubility. Once the dithiocarbamate was generated, the desulfurylation step using TCT proceeded smoothly for all amines. The branched alkylamines, cyclic alkylamines and benzylamines showed

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• failed with tosylamine and benzylcarbamate, whereas aryl-, alkyl- and benzylamines were used successfully in this reaction (Scheme 25). A three-component reaction involving in the first step a Sonogashira coupling of o-haloanilines 57 with terminal alkynes and leading to o-alkynylaniline intermediates 58