p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• towards highly electrophilic p-nitrophenyl carbonate derivatives with ring opening of the bicyclic ring to form corresponding substituted ε-caprolactam and γ-lactam derived carbamates. This simple method presents a unified strategy to synthesize structurally diverse ε-caprolactam and γ-lactam compounds

• behavior of DBU towards imidazolides providing ε-caprolactam-derived carbamates and amides [17]. Here, in this report we present the results obtained by the reaction of DBU and DBN with highly electrophilic p-nitrophenyl carbonates leading to ε-caprolactam and γ-lactam carbamates. p-Nitrophenyl carbonates

• in the solvent, leading to the ring opening and formation of the corresponding caprolactam carbamates (Scheme 1). The structure of 1b was confirmed by 1H and 13C spectroscopy, which showed the characteristic carbamate NH triplet at 5.80 ppm in the 1H NMR spectrum and the expected peaks at 176.6 and

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• ). Similarly, silyl reagents also failed to afford the desirable products under the optimized conditions. Based on above observations and understandings toward the mechanism, a modified protocol was designed by introducing the secondary amide containing reagents such as allylsilanes, carbamates, etc, where the

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• including alcohols, halides, esters, amides, carbamates and sulfonamides are compatible with the metathesis conditions [14][15][16][17][18][19][20]. However, the involvement of alkenes containing a nitrogen atom such as an amine or an N-heteroaromatic ring in metathesis reactions is still problematic and

• allow the use of primary and secondary amines in ring-closing metathesis (RCM) and cross-metathesis (CM), and one of them is the transformation of amines into carbamates, amides or sulfonamides [27][28][29]. As an alternative, metathesis reactions can be performed with olefins possessing ammonium salts

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

• cyclic imides, carbamates, sulfonamides and indoles. On the other hand, the successful amidation using different alkynes, including aryl-, alkyl- and silyl-functionalized alkynes proved the broad scope of application of this method (Scheme 19). Following the design of this method, a heterogeneous

• catalytic protocol was later developed by Mizuno et al. [74] for the amidation of terminal alkynes using lactam, sulfonamide or cyclic carbamates. The application of Cu(OH)2 as heterogeneous catalyst allowed the synthesis of ynamides 77 with moderate to excellent yield under air (Scheme 20). A latest work

Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides

• Armando Navarro-Vázquez

Beilstein J. Org. Chem. 2015, 11, 1441–1446, doi:10.3762/bjoc.11.156

• Armando Navarro-Vazquez Departamento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Cidade Universitária - Recife, PE - CEP 50.740-560, Brazil 10.3762/bjoc.11.156 Abstract The base-catalyzed isomerization of N-propargylamides or carbamates may

• employing harsh reaction conditions. The outcome of the isomerization process seems to subtlety depend on the structural features of the N-propargyl compound. Similar issues have been observed for carbamates or phosphoramides [8]. In summary, the isomerization process is not yet well understood and, quoting

• for the corresponding isomers for a selected combination of starting amides or carbamates and a final urea example (Figure 1) were computed using ab initio and DFT methods. Results and Discussion Computational procedures It is known that ab initio prediction of cumulene–polyynes isomerization energies

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• work for electron-deficient anilines. Despite this limitation, Hii and co-workers expanded the methodology to other α,β-unsaturated N-alkenoylbenzamides [238] and carbamates [239][240] (Scheme 32). In order to find means to overcome the low enantioselectivities observed when electron-rich anilines are

Molecular cleft or tweezer compounds derived from trioxabicyclo[3.3.1]nonadiene diisocyanate and diacid dichloride

• Gert Kollenz,
• Ralf Smounig,
• Ferdinand Belaj,
• David Kvaskoff and
• Curt Wentrup

Beilstein J. Org. Chem. 2015, 11, 1–8, doi:10.3762/bjoc.11.1

• ability to extract some alkali, alkaline earth and rare earth metal ions. Keywords: carbamates; crown ethers; diisocyanate; isocyanate; ureas; Introduction The synthesis of the surprisingly stable, monomeric diisocyanate 1 (Figure 1) was reported recently [1]. This and several other derivatives of the

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

• electrolysis of carbamates to accumulate the N-acyliminium ion reactive intermediate then under non-oxidative conditions the nucleophile is introduced. Importantly, the nucleophile cannot be present when the N-acyliminium ion is being formed under electrochemical conditions, as in most cases it is easier to

• oxidise the nucleophile than the amide precursor. This circumvents the need to prepare, trap and release the N-acyliminium cation under more favourable conditions, allowing the direct α-alkylation or arylation of carbamates (Scheme 3); the cation pool method has been extensively studied [17][18][19][20

• ][21][22][23][24][25][26][27][28][29][30][31]. The use of electroauxiliaries The concept of electroauxiliaries has proven useful for developing and expanding the scope of the Shono-type oxidation of carbamates; electroauxiliaries activate organic compounds towards electron transfer controlling the fate

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• temperatures and pressures to activate CO2 [2][3]. Efficient chemical incorporation of CO2 is limited to rather reactive substrates, like epoxides [4][5][6] and amines [7][8][9] to produce cyclic carbonates and carbamates, respectively, and even then, elevated reaction temperatures and/or complex catalyst

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• sugars 1 and 2 we neutralized the corresponding hexosamine hydrochlorides 5 and 6 with sodium methoxide and coupled them to the activated cyclopropene 7 (Scheme 2), the synthesis of which we reported previously [24]. Subsequent acetylation of the carbamates 8 and 9 gave Ac4GlcNCyoc (1) and Ac4GalNCyoc (2

Efficient CO₂ capture by tertiary amine-functionalized ionic liquids through Li⁺-stabilized zwitterionic adduct formation

• Zhen-Zhen Yang and
• Liang-Nian He

Beilstein J. Org. Chem. 2014, 10, 1959–1966, doi:10.3762/bjoc.10.204

• in the respective carbamates (onium salts) [39]. As previously reported, strong amidine and guanidine bases such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) can form the base-CO2 zwitterionic adduct in a 1:1 manner under strictly anhydrous conditions (Scheme 1c) [40][41]. Herein, we present such a

A promising cellulose-based polyzwitterion with pH-sensitive charges

• Thomas Elschner and
• Thomas Heinze

Beilstein J. Org. Chem. 2014, 10, 1549–1556, doi:10.3762/bjoc.10.159

• in vacuum at room temperature, dissolved in 10 mL water, dialyzed against deionized water, and finally lyophilized. Yield: 71% Reaction scheme of the synthesis of anionic, cationic, and ampholytic cellulose carbamates (substituents randomly distributed). 13C NMR spectra of (3-ethoxy-3-oxopropyl)(N

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• analogues, we were in need for a more versatile protecting group pattern. We therefore investigated different carbamates as protecting groups for the amino functionality, leading to the secondary alcohol functionality being selectively accessible for further conversions. We discovered that we were in need

Synthesis of fluorescent (benzyloxycarbonylamino)(aryl)methylphosphonates

• Michał Górny vel Górniak,
• Anna Czernicka,
• Piotr Młynarz,
• Waldemar Balcerzak and
• Paweł Kafarski

Beilstein J. Org. Chem. 2014, 10, 741–745, doi:10.3762/bjoc.10.68

• aldehydes and benzyl carbamates (the so called Oleksyszyn reaction) for the synthesis of fluorescent (benzyloxycarbonylamino)(aryl)methylphosphonates. Results and Discussion Synthesis of diaryl (benzyloxycarbonylamino)(phenyl)methylphosphonates Diaryl esters of Z-protected aminobenzylphosphonic acid were

Concise, stereodivergent and highly stereoselective synthesis of cis- and trans-2-substituted 3-hydroxypiperidines – development of a phosphite-driven cyclodehydration

• Peter H. Huy,
• Julia C. Westphal and
• Ari M. P. Koskinen

Beilstein J. Org. Chem. 2014, 10, 369–383, doi:10.3762/bjoc.10.35

• aspartic acid mono ester was obtained in a 5:1 ratio with the diester (not shown) after approximately 18 h of reaction time. Shorter reaction times in the esterification step of 1f decreased the yield of 8f. The amines 8e and 8f were converted in a straightforward manner to the carbamates 2e and 2f under

Synthesis of novel derivatives of 5-hydroxymethylcytosine and 5-formylcytosine as tools for epigenetics

• Anna Chentsova,
• Era Kapourani and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 7–11, doi:10.3762/bjoc.10.2

• (lithium (trimethylsilyl)acetylide, THF, −60 °C → −50 °C or lithium phenylacetylide, THF, −78 °C) afforded derivatives 6a–c and carbamates 7a–c as mixtures of diastereomers (Table 2). It should be mentioned that upon storage at room temperature derivatives 6a–c undergo slow intramolecular cyclization to

• the corresponding carbamates 7a–c. The reaction of aldehyde 4 and vinylmagnesium bromide yielded directly carbamate 7d. Surprisingly, the reaction of derivative 5 bearing a N-(TCBoc)2 group with organometallic compounds (methylmagnesium bromide, THF, 0 °C → room temperature, lithium (trimethylsilyl

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• addition of carbamates, sulfonamides and imidazolidinones to linear and cyclic dienes 17 in the presence of catalytic amounts of PPh3AuOTf (Scheme 6). The method featured excellent 1,2-regioselectivity and high chemoselectivity, providing protected allylamines 18, in good yields, using nearly equimolar

• amounts of the diene and nitrogen-based nucleophile. Analogously, Widenhoefer and Han developed the intramolecular addition of carbamates to terminal alkenes affording N-protected pyrrolidines and piperidines 21 (Scheme 7). Best conditions involved the use of a 1:1 mixture of [Au(I)] complex 20a and AgOTf

• importance of the configuration of the carbon bearing the nucleophilic OH group was not considered. In this segment, Widenhoefer has recently documented on the enantioselective dehydrative amination of allylic alcohols with carbamates [70][71]. Pyrrolidines and piperidines 109 were obtained with enantiomeric

An approach towards azafuranomycin analogs by gold-catalyzed cycloisomerization of allenes: synthesis of (αS,2R)-(2,5-dihydro-1H-pyrrol-2-yl)glycine

• Jörg Erdsack and
• Norbert Krause

Beilstein J. Org. Chem. 2013, 9, 1936–1942, doi:10.3762/bjoc.9.229

• )}. For the debromination of dihydropyrrole 19, we first tested radical conditions ((n-Bu)3SnH/AIBN), but these led to complete decomposition. This is surprising since carbamates are known to be stable under radical conditions [70]. Indeed, treatment of diastereomer 11b with (n-Bu)3SnH/AIBN afforded the

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• possess a complementary donor–acceptor hydrogen bond motif, such as for instance amides, ureas, carbamates, saccharides, ammonium carboxylate salts, etc. A rod-like molecular shape is also a general structural requirement for steroid derived LMOGs because it allows a good face to face molecular contact to

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• aniline is crucial. Methyl substitution leads to slower addition than phenyl substitution. Carbamates as substituents are suitable only when the radical center is not too electrophilic. No correlations between free reaction barriers and energies (ΔG‡ and ΔGR) are found. Addition reactions leading to

• –HOMO gap. Thus, the polarity of the radical and the arene is reversed in comparison with the related Minisci reaction. The substitution at the N-atom of the aniline is crucial. Methyl substitution leads to slower addition than phenyl substitution. Carbamates as substituents are suitable only when the

ML212: A small-molecule probe for investigating fluconazole resistance mechanisms in Candida albicans

• Willmen Youngsaye,
• Cathy L. Hartland,
• Barbara J. Morgan,
• Amal Ting,
• Partha P. Nag,
• Benjamin Vincent,
• Carrie A. Mosher,
• Joshua A. Bittker,
• Sivaraman Dandapani,
• Michelle Palmer,
• Luke Whitesell,
• Susan Lindquist,
• Stuart L. Schreiber and
• Benito Munoz

Beilstein J. Org. Chem. 2013, 9, 1501–1507, doi:10.3762/bjoc.9.171

• tert-butyl carbamates 5 prior to undergoing palladium-mediated Suzuki reactions with various boronic acid partners. Under the reaction conditions, the carbamate-protecting group was also cleaved to afford the desired 3-arylindazoles, albeit as the unprotected systems 6. Alkylation with methyl

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• derivatives. The scope of the reaction was investigated and its applicability was extended to different C–H bonds, including benzylic, propargylic, and aliphatic ones. Furthermore, the hydrazine compounds were readily converted to the corresponding carbamates and amines. Conclusion Metal-free oxidation

Gold-catalyzed oxycyclization of allenic carbamates: expeditious synthesis of 1,3-oxazin-2-ones

• Benito Alcaide,
• Pedro Almendros,
• M. Teresa Quirós and
• Israel Fernández

Beilstein J. Org. Chem. 2013, 9, 818–826, doi:10.3762/bjoc.9.93

• gold-catalyzed synthetic routes to 1,3-oxazinan-2-ones (kinetically controlled products) and 1,3-oxazin-2-one derivatives (thermodynamically favored) from easily accessible allenic carbamates has been carried out. Keywords: allenes; computational chemistry; gold; gold catalysis; heterocycles; reaction

• substrates on gold-catalyzed oxycyclization reactions, a number of new allenic carbamates were synthesized as shown in Scheme 1. Starting materials, tert-butyl (prop-2-ynyl)carbamates 1a–j, were obtained both in the racemic form and in optically pure form by using standard methodologies. Thus

• readily accessed from (S)-prolinol by using a modified known procedure [58]. Alkynylcarbamate 1j was achieved through the reaction of 3-bromo-1H-indole-2-carbaldehyde with the Ohira–Bestmann reagent followed by the addition of Boc2O. Terminal alkynes 1 were conveniently converted into allenic carbamates 2

Recent progress in the discovery of small molecules for the treatment of amyotrophic lateral sclerosis (ALS)

• Allison S. Limpert,
• Margrith E. Mattmann and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2013, 9, 717–732, doi:10.3762/bjoc.9.82

• prodrugs for their potential use in the treatment of glutamate toxicity in ALS and other disorders. Potential drug candidates were prepared through the conversion of the exocyclic amine to single alpha amides, carbamates, succinamides, or amide linkages from γ-aminobutyric acids (Figure 2). It is expected

Carbolithiation of N-alkenyl ureas and N-alkenyl carbamates

• Julien Lefranc,
• Alberto Minassi and
• Jonathan Clayden

Beilstein J. Org. Chem. 2013, 9, 628–632, doi:10.3762/bjoc.9.70

• Julien Lefranc Alberto Minassi Jonathan Clayden School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK 10.3762/bjoc.9.70 Abstract N-Alkenyl ureas and N-alkenyl carbamates, like other N-acyl enamines, are typically nucleophilic at their β-carbon. However, by

• incorporating an α-aryl substituent, we show that they will also undergo attack at the β-carbon by organolithium nucleophiles, leading to the products of carbolithiation. The carbolithiation of E and Z N-alkenyl ureas is diastereospecific, and N-tert-butoxycarbonyl N-alkenyl carbamates give carbolithiation

• -alkenyl carbamates. Results and Discussion Simple N-alkenyl ureas 1 were prepared by a reported method [2] entailing N-acylation of an acetophenimine with an isocyanate, followed by N-alkylation of the resulting urea. When urea 1a was treated with t-BuLi or s-BuLi in THF at −78 °C for one hour, followed