Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• the formation of N-substituted indole derivatives from N-substituted anilines. The direct PdI2/KI oxidative carbonylation of 2-alkynylanilines does not lead to the formation of indole-3-carboxylic esters but to the formation of acyclic carbamates. For this reason, they performed the reaction in the

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• have been masked by the high temperatures and long reaction times of early reports. For example, Widenhoefer engaged carbamates and amides in dioxane at temperatures >80 °C [12][13]. Later work showed that ureas could be engaged at room temperature when a NHC–gold catalyst system was used, outpacing

• acetamides, which in turn outpaced carbamates [14]. In work by Michon and co-workers, a substrate survey in TCE at 80 °C revealed that tosylsulfonamide 1d was reactive, while the corresponding acetamide was not, and carbamates were seen as especially reactive, privileged substrates [8]. Our results are not

• . Carbamates, sulfonamides, and amides display significantly reduced reactivity, if any [56][57]. Titration experiments with MeOH-d4 (further discussion below) reveal that overall reaction rates for urea 1a and carbamate 1b appear to correlated with rates of gold-mediated N–H/D exchange which may further

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• 1b. Wherein various alkyl and aryl olefins, including those that contain Lewis basic esters, carbamates and amines or α-branched moieties, may be used in efficient and exceptionally Z-selective cross-metathesis reactions [6][7][8]. A few years ago, some publications devoted to the cleavage of the C–F

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• [24][25]. Interestingly, Jacquemard et al. outlined a useful, mild method for removing a range of carbamates using Bu4NF in an article from 2004 [26]. As 7 contained a DTBS group, the possibility of removing both Troc and DTBS groups in a one-pot procedure was tested. Disaccharide 7 was therefore

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• , such alcohols were in situ converted into the corresponding O-allyl carbamates as leaving groups, followed by their reaction with imidazoles, affording the SN2’ products 3 (Scheme 1, reaction 1, iii). Correlatively, we have previously reported a direct amination of cyclic MBH alcohols 4 with morpholine

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• with amino and nitro groups due to side processes on the electrodes. Cyclic carbamates were oxidized to lactams using ABNO derivatives as electrocatalysts [104] (Scheme 16A). The substrates with easily oxidizable pyrazole and oxazole fragments reacted successfully under these conditions. Under similar

• electrochemical oxidation of primary alcohols and aldehydes to carboxylic acids. Electrocatalytic oxidation of benzylic alcohols by a TEMPO derivative immobilized on a graphite anode by π–π stacking interactions. Electrochemical oxidation of carbamates of cyclic amines to lactams and oxidative cyanation of amines

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• cage nitrogen atoms) and/or rotamers (restricted rotation around amide C–N bonds), which is well-known for amides and carbamates (Figure 4a). The activation barriers for the rotation across amide C–N bonds in 4a and 4c estimated by DFT (18.4 and 19.4 kcal/mol, respectively, ωB97XD/Def2TZVP, gas phase

• ) are close to those observed experimentally for amides and carbamates [42][43]. Upon changing the solvent to CD3OD or D2O the spectra become much simpler and a picture expected for a Cs symmetrical structure is observed (for example, cf. 1H NMR spectra of Bn-4c in different solvents shown in Figure 4b

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• necessary in some cases (path b in Scheme 1) [14][15]. On the other hand, N-acyliminium ions can easily be generated by electrochemical oxidation without those reagents. Electrochemical oxidation of amides/carbamates yielding N-acyliminium ions is well known as Shono oxidation (path c in Scheme 1) [16] and

• has also been applied to organic synthesis [17][18][19][20]. However, when electrochemical oxidation of amides/carbamates in the presence of nucleophiles, such as electron-rich arenes or silyl enol ethers, is carried out for Friedel–Crafts-type amidomethylation, electrochemical oxidation of electron

• -rich arenes or silyl enol ethers preferentially takes place at the anode due to their, in general, more positive oxidation potentials than those of amides/carbamates. Therefore, Friedel–Crafts-type amidomethylation by using Shono oxidation is successfully carried out as a two-step process

A versatile way for the synthesis of monomethylamines by reduction of N-substituted carbonylimidazoles with the NaBH₄/I₂ system

• Lin Chen,
• Xuan Zhou,
• Zhiyong Chen,
• Changxu Wang,
• Shunjie Wang and
• Hanbing Teng

Beilstein J. Org. Chem. 2022, 18, 1032–1039, doi:10.3762/bjoc.18.104

• attacked by a nucleophile the imidazole group readily dissociates. The N-substituted carbonylimidazoles have favorable reactivity and can be widely used in the synthesis of various valuable products such as ureas [63][64][65][66][67][68][69][70], carbamates [66][71][72][73][74], thiocarbamates [66], and

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• ethyl chloroformate/Et3N, followed by Wittig olefination with an ylide generated from (methoxymethyl)triphenylphosphonium chloride and LDA to give the enol ethers as E/Z mixtures. N-Phenethyl carbamates were obtained from benzaldehydes via Henry reaction with nitromethane, followed by zinc dust

• enantiomerically pure alkaloids, as numerous methods for separation of enantiomers are well known in this field [52][53][54][55]. Further, this protocol might be extended to an asymmetric N-acyl-Pictet–Spengler condensation by using homochiral carbamates, as demonstrated by Comins [18], or by using

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

• secondary and tertiary amines, amides/lactams/carbamates, and nitrile. The test reactions were monitored by thin-layer chromatography (TLC) and, where deemed necessary, results were further verified by GC–MS. The reagents employed encompassed tritylium tetrafluoroborate [50], H2O2/HBr [42], ceric ammonium

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• subsequently deprotonates pyrrole to provide the stronger nucleophilic pyrrolide anion [27]. Similarly, Liu et al. accomplished an asymmetric intramolecular aza-Michael addition of various enone carbamates 10 using a chiral cinchona-based primary-tertiary diamine as catalyst to obtain 2-substituted piperidines

• of carbamates, sulfonamides and acetamides 13 bearing an α,β-unsaturated ketone to synthesize a series of 2-substituted five- and six-membered heterocycles in good yields (up to 99%) and excellent enantioselectivity (92–97.5% ee) (Table 3). As in an earlier case [29], several acids were tested as co

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

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

• also tolerable to functional groups, such as silyl ethers (52a), carbamates (52b), and heterocycles (52c), present in the olefin moiety. The initial mechanism proposed by the authors begins with the formation of Fe(III) hydride species (A), followed by hydrogen atom transfer to the olefin in a

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• aminohydroxylation process starting from allylic carbamates usually carried out in the presence of potassium osmate [24][25][26][27][28]. In recent years, we have extensively studied the stereoselective synthesis, as well as catalytic and pharmacological applications of monoterpene-based 3-amino-1,2-diols, which are

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• -one. Mechanism for the Lewis acid-catalyzed synthesis of tetrahydropyran-4-one. Hoveyda and co-workers’ strategy for 2,6-disubstituted 4-methylenetetrahydropyran. Funk and Cossey’s ene-carbamates strategy. Yadav and Kumar’s cyclopropane strategy for THP synthesis. 2-Arylcylopropylmethanolin in

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

• trifluoromethylation (Scheme 25). A variety of olefins, such as ene carbamates, styrene, aliphatic olefins, vinyl ethers, and acrylates are compatible in this approach, affording corresponding β-(trifluoromethyl)alkynes with good to excellent yield. The bifunctionalization was achieved by an EDA-complex-initiated

Coupling biocatalysis with high-energy flow reactions for the synthesis of carbamates and β-amino acid derivatives

• Alexander Leslie,
• Thomas S. Moody,
• Megan Smyth,
• Scott Wharry and
• Marcus Baumann

Beilstein J. Org. Chem. 2021, 17, 379–384, doi:10.3762/bjoc.17.33

• . A variety of different acid substrates including benzoic acids, phenylacetic acids, and various non-aromatic acids successfully underwent the above continuous Curtius rearrangement process giving the desired Cbz-carbamates in good yields (Figure 1). As expected, benzoic acids cleanly and rapidly

• rearranged within a residence time of 30 minutes rendering the corresponding carbamates 3a–e in high chemical yields. Phenylacetic acid species were found to be less reactive substrates that rearranged more slowly (tRes = 60 min) and thus giving lower yields (3f–h). Moreover, the formation of urea side

• migratory aptitude which in turn translated into a higher chemical yield towards the corresponding carbamate structure 3i. Lastly, a set of non-aromatic acids was subjected to the same reaction conditions providing access to carbamates bearing cyclohexyl, cyclobutyl, and vinylic appendages (3j–m). An

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• cyclocondensation of N-(trifluorochloroethylidene) carbamates IV with β-amino crotonates V led only to 4-trifluoromethylpyrimidin-2(1H)-ones I bearing a 5-alkoxycarbonyl substituent (R3/6 = CO2Alk) due to the strong structural limitations of the nucleophilic enamine component (see Figure 1а, method В) [31]. The

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

•  26B). The reaction conditions were also amenable to carbamates, affording the products 64–67 in moderate to good yield (42–58%). That the carbamate oxygen atom could direct the fluorination α to itself instead of α to the amide nitrogen atom provided an inverted, complementary selectivity as expected

• previously for benzylic fluorination [130]. In a later perspective [36], the authors speculated that the amide served as a directing group. Indeed, in situ-formed ammonium carbamates were recently identified to direct the HAT of a quinuclidinium radical cation [208]. 3.5 Scalability of C–H fluorinations That

Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• chemists. Accordingly, MBH adducts have been explored as strategic intermediates for the synthesis of interesting molecules, such as carbamates of unsaturated β-amino acids [1], β-phenylsylfenyl-α-cyanohydrocinnamaldhydes [2], 2-alkylcarbonyl-1-indanols [3], dihydropyrazoles [4], tetrahydroacridines [5], γ

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• in low to good yields by the reaction of 2-(1-haloalkyl)oxiranes 142 and 147 with ammonium monothiocarbamates 148 as the sulfur nucleophiles. First, a nucleophilic ring-opening of the oxiranes 142 and 147 by monothiocarbamates 148 gave rise to the S-(γ-halo-β-hydroxyalkyl)carbamates 149 with release

• of amines. The latter then aminolyzed the carbamates 149 to generate ureas 151 and γ-halo-β-hydroxyalkanethiols 150. The intermediates 150 further underwent an intramolecular cyclization to produce the thietane-3-ols 145 in low to good yields [58] (Scheme 30). Paclitaxel (Taxol®) and docetaxel

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• -systems: heteroarenes and electron-poor alkenes in particular. Using the tools of organophotocatalysis, this reactive intermediate can be directly obtained from carbonyl derivatives, such as aldehydes, α-keto acids, oxalates, or carbamates through oxidative or reductive decarboxylations, oxidative