Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis

• Quentin Lefebvre,
• Christophe Salomé and
• Thomas C. Fessard

Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87

• of complex amines: bicyclopentanamines, azetidines, spiroazetidines, spiropyrrolidines and spiropiperidines. Functional group tolerance was probed by using functionalized building blocks bearing esters, carbamates, alcohols, tertiary amines, ethers, sulfones and fluorine atoms (Scheme 2 and Scheme 3

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• group were investigated. Instead of the N-phenyl group, other protecting groups such as acetyl, benzoyl, or carbamates were tested, but the corresponding starting materials proved to be unreactive in the desired transformation. The use of substituted N-phenyl groups revealed that almost all of the

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• DNA-photocleavers, and are proposed as new leads for “on demand” biotechnological applications in drug discovery and medicine. Keywords: DNA binding; DNA photocleavage; N–O homolysis; oxime carbamates; photocleavage agents; Introduction Small organic molecules able to bind DNA provide promises for

• radicals are also produced from 2-(1-naphthylmethyl)imidazoline [35], whereas acylaminyl radicals [R(COR)N∙] are formed from the photocleavage of the N–O bond of N,O-diacyl-N-phenylhydroxylamines, along with a carbonyloxyl radical [38]. The photochemistry of O-carbamoyl oximes (or oxime carbamates) is well

• studied. These compounds are categorized as highly photoreactive photobase generators (PBGs), providing amines upon rapid decarboxylation of the initially formed carbamoyloxyl radicals (R2NCOO∙) [49][50][51][52][53]. To the best of our knowledge oxime carbamates have never been photocleaved in the

Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

• Thomas J. Cogswell,
• Craig S. Donald and
• Rodolfo Marquez

Beilstein J. Org. Chem. 2020, 16, 135–139, doi:10.3762/bjoc.16.15

• , acrylamide was used in an analogous manner to the carbamates employed by Veenstra (Scheme 1) [19]. In our initial attempts, the solvent was changed from dichloromethane to acetonitrile due to solubility issues with the acrylamide and the postulated imine intermediate. The reaction proved sluggish, taking

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

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• demanding cinchona groups. Additionally, some of these new CD derivatives showed promising results of up to 75% ee in the AAA reactions of Morita–Baylis–Hillman (MBH) carbamates and significant differences depending on the attached cinchona alkaloid (cinchonine, cinchonidine, quinine, quinidine) as well as

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• we have proposed for photocatalytic oxyamination is outlined in Figure 1c. Photoinduced one-electron oxidation of an appropriately electron-rich styrene 1 results in the formation of a radical cation 1•+ that is susceptible to attack by various heteroatomic nucleophiles, including carbamates [21][22

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

• generate the reactive species by dehydration of carbamates under mild conditions and the ultimate formation of isocyanates which can be derivatized in situ [54]. The conditions were optimized with alcohol 25 substituted by a 2-phenylethyl group at the oxygen-bearing carbon atom (C4) and possessing gem

• , reaction with pyrrolidine, imidazole, methanol, allyl alcohol, benzyl alcohol and 9-fluorenemethanol (FmOH) provided the corresponding urea 30, N-carbamoyl imidazole 31 and carbamates 32–35, respectively, in good yields (69–80%). The reaction of isocyanate 28 with tert-butanol was sluggish even by heating

• with allyl alcohol. Benzylidenecyclopropane 41 was also obtained in good yield (70%) but the efficiency of the sigmatropic rearrangement dropped for carbamates in which the aromatic group at C4 is substituted by an electron-withdrawing group at the para-position. Indeed, N-Alloc (arylmethylene

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• synthesis of the carbamate-protected glycal of L-vancosamine 1 and L-saccharosamine 2 were prepared in two steps by treatment of alcohols with the trichloroacetyl isocyanate reagent (TCA-NCO) followed by basic hydrolysis. The spectroscopic properties of carbamates 17 were identical to those reported in the

• afford the epimeric product 26. Both diastereomers 23 and 26 were converted to the corresponding known carbamates using a two step sequence. Reaction with TCA-NCO followed by a basic hydrolysis provided the desired compounds 24 and 27 in good yields and in full agreement with all reported spectroscopic

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• carbamates, urea and non-basic heterocycles (Scheme 11) [54]. The scope covers a multitude of electron-poor and electron-rich arenes which can be reacted with carbamates, urea, pyrazole and triazole derivatives to furnish aminated products. The authors address the various reactivities observed with respect

An amine protecting group deprotectable under nearly neutral oxidative conditions

• Shahien Shahsavari,
• Chase McNamara,
• Mark Sylvester,
• Emily Bromley,
• Savannah Joslin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

• including 3a–d gave good to excellent isolated yields of carbamates 5a–d (Table 1, entries 1–4). Under these conditions, however, secondary aliphatic amines could not react or could react but gave very low yields. We tried a variety of other conditions such as deprotonating the amine followed by reacting

• any special devices such as an electrochemical cell. Therefore, the dM-Dmoc carbamates were first oxidized with sodium periodate at room temperature. After removing the excess oxidizing agent and other inorganic salts by filtration, β-elimination to give the amine products was initiated with the weak

• . General procedure for dM-Dmoc protection of aliphatic amines – synthesis of carbamates 5a–d: To a solution of an amine (0.292 mmol, 1 equiv) and DIPEA (0.255 mL, 1.46 mmol, 5 equiv) in dry THF (10 mL) was added 4 (0.100 g, 0.292 mmol, 1 equiv) at rt under argon. After stirring for 8 h, the reaction was

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• carbamates [92], sulfamates [94][95][96][97], ureas and guanidines [98], sulfamides [99], hydroxylamine-derived sulfamates [100], carbamimidates [101], and sulfonimidamides [102][103][104][105][106][107]. These reactions involve the formation of a metal-bound nitrene that can insert into a C(sp3)–H bond or a

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• than LD interactions and are mainly responsible for the observed stabilization effects, which is also represented as a blue surface in the NCI plot of (R,S)-4 c1. Furthermore, it is known that amides form stronger hydrogen bonds than carbamates and the strength also depends on the steric bulk of the

Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis

• Tatiana Golub and
• James Y. Becker

Beilstein J. Org. Chem. 2018, 14, 861–868, doi:10.3762/bjoc.14.72

• ). It has been found that anodic methoxylation of amides (and carbamates) can be utilized to form new carbon–carbon bonds [6][7] (Scheme 2). Furthermore, this anodic route could also be important from a synthetic point of view, affording ring-expansion [8][9][10] and annulation of rings [1][11][12

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• mild and efficient C–H alkenylation of N-pyrimidylindoles and pyrroles with alkenyl acetates using a cobalt–NHC catalyst (Scheme 1a) [17]. The same catalytic system also promoted the alkenylation using alkenyl carbamates, carbonates, and phosphates. More recently, we have achieved an N-arylimine

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• crown-5 derivative 31 showed an enhanced ability to extract Na+ and K+ ions from water into CHCl3 (22 and 21%, respectively, within 10 minutes using equimolar amounts of salt and ligand) [37]. In the concave structures of the bisdioxines, the functional groups such as esters, amides, carbamates

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

• Jury J. Medvedev,
• Ilya V. Efimov,
• Yuri M. Shafran,
• Vitaliy V. Suslonov,
• Vasiliy A. Bakulev and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253

• reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It

• -aminothiophen-3-yl)carbamates 5, which could be formally referred to as the derivatives of carbamates 3, 5 and heteroaromatic amines 4. To elucidate the reasons for the low reactivity of diazoesters 2a,b with thioamides 1 in the considered catalytic processes, the interaction of thioacetamides 1a–e with Rh2(Piv

• ylide with the rhodium catalyst. Within the adopted general scheme, the occurrence of thiophenes 4 could be rationalized by partial hydrolysis of carbamates 3 under the reaction conditions with the initial formation of the primary heteroaromatic amines 7. The latter then interact with carbenoids A, to

Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity

• Henryk Myszka,
• Patrycja Sokołowska,
• Agnieszka Cieślińska,
• Andrzej Nowacki,
• Maciej Jaśkiewicz,
• Wojciech Kamysz and
• Beata Liberek

Beilstein J. Org. Chem. 2017, 13, 2310–2315, doi:10.3762/bjoc.13.227

• the condensation of saccharides with ureas or the reaction of glycosylamines, amino sugar, or aminoglycosides with isocyanates, or their equivalents such as carbamates [32][33]. Ureido saponins presented here were obtained in the reaction of ethyl isocyanate (8), chloroethyl isocyanate (9) and phenyl

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• (vinylogous carbonates and carbamates) normally requires more forcing conditions, but usually can be facilitated by addition of catalytic amounts of organic base (Scheme 2) [43]. Interestingly, we figured out that the presence of heteroatom X in the structure of enol 6 is important for the normal course of

• -catalyzed spirocyclization of enoles (vinylogous carbonates and carbamates) with 5-methoxycarbonyl-1H-pyrrolediones. Acid-catalyzed spirocyclization of enoles (vinylogous carboxylates) with 5-alkoxycarbonyl-1H-pyrrolediones. Formation of mono-imines and mono-hydrazones of 1,3-cyclohexanediones and

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

• 65–81% of trans-esterified product (Scheme 21). Differently substituted benzene rings including hetero-aromatics were also well tolerated under the similar condition. Colacino and co-workers reported the preparation of carbamates by using 1,1’-carbonyldiimidazole (CDI) and in presence of either

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• Ackermann group used another ruthenium catalyst, [RuCl2(p-cymene)]2 and developed a hydroxylation protocol for carbamates [77]. The hydroxylation occurred in DCE in the presence of PhI(OTFA)2 (Scheme 47). In intermolecular competition experiments, among amide, carbamate and ester, amide showed the highest

• ketones. The Rao group developed a catalytic system of [RuCl2(p-cymene)]2 and K2S2O8 in TFA/TFAA, which promoted the hydroxylation of ethyl benzoates, benzamides and carbamates (Scheme 49). They reported the first ortho-hydroxylation of ethyl benzoates in 2012 [79]. Both electron-rich and electron

• , CF3, ester, etc.) and electron-donating functional groups (such as methyl, methoxy, etc) were well tolerated. In 2014, the tolerance of this protocol for carbamates and esters was studied [81]. Carbamates were compatible with this protocol, however, esters gave lower yields. A replacement of [RuCl2(p

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• (0.33 ms) under cryogenic conditions. By using such an incredible short residence time, it was possible to overtake the very rapid anionic Fries rearrangement, and chemoselectively functionalize ortho-lithiated aryl carbamates (Scheme 7). This CMR has been developed choosing a fluoroethylene propylene

Solution-phase automated synthesis of an α-amino aldehyde as a versatile intermediate

• Hisashi Masui,
• Sae Yosugi,
• Shinichiro Fuse and
• Takashi Takahashi

Beilstein J. Org. Chem. 2017, 13, 106–110, doi:10.3762/bjoc.13.13

• serinate using Fmoc–OSu or CbzCl afforded the corresponding carbamates in good yields (Table 1, experimental details, see Supporting Information File 1). Acetal formation and reduction were performed by the developed procedure in ChemKonzert (Table 1). The Garner’s aldehydes containing an Fmoc or Cbz

• protecting group (PG) could be synthesized from the corresponding methyl ester; however, lower yields were obtained for the DIBAL reduction, probably due to the DIBAL-mediated removal of the carbamates [32]. Conclusion In conclusion, the first solution-phase automated synthesis of 4a (Boc protection) was

Robust C–C bonded porous networks with chemically designed functionalities for improved CO₂ capture from flue gas

• Damien Thirion,
• Joo S. Lee,
• Ercan Özdemir and
• Cafer T. Yavuz

Beilstein J. Org. Chem. 2016, 12, 2274–2279, doi:10.3762/bjoc.12.220

• formation. Carbamates form with the contribution of two amines and carbamic acid needs one amine and a water molecule. The presence of moisture, therefore, favors the formation of carbamic acids and leads to higher uptake capacity per sorbent mass. We performed moist CO2 uptake experiments in order to mimic