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

• spirocyclization via conversion of 1,3-diones 8 into mono-hydrazones. Indeed, while mono-imines of these ketones strongly prefer keto-enamine tautomeric form 13 over enol-imine form 14 (Scheme 4) [44][45], the corresponding hydrazones have been reported to favor enol-hydrazone tautomer 16 (Scheme 4) [46][47][48

• -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

• the sole products. Contrastingly, in the solution of acetonitrile imines of benzaldehyde and amines were formed preferably. Different aromatic or heteroaromatic aldehydes including thiophene carboxaldehyde, pyridine carboxaldehyde and cyclohexyl carboxaldehyde as well as various amines like morpholine

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• high selectivities was the use of a dual catalyst system consisting of G2 as the anionic PTC and amino acids I for in situ formation of a more reactive enamine intermediate which then undergoes the stereoselective α-fluorination followed by hydrolysis of the resulting imines to give targets 11 [83]. α

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

• of imides with alkyl halogenides, and the results are presented in this paper. Until now, ball milling N-alkylations of ureas [15], hydrazones [16], imines [17][18], pyridines [19], pyrimidines [20], imidazoles [21], secondary amines [22], as well as allylic alkylation reactions [23] were reported in

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• -workers in the year 2000 [26][27][28][29]. It oxidizes diverse functionalities such as amines, imines, alcohols etc. [30]. Later, it was demonstrated that IBX can also be used as a reagent for oxidative dehydrogenation of benzylic carbons in various aromatic systems via single electron transfer (SET) and

• /or ionic pathways [31][32][33][34]. It was not until 2004, that IBX was applied in the oxidative dehydrogenation of functionalized cyclic and acyclic ketones [31][32][33][34]. IBX was further harnessed in the oxidative dehydrogenation of 2°-amines, N-hydroxides, imines and oximes [31][32][33][34

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• HPA and an imine component which has been postulated but never obtained in similar reactions. Keywords: Castagnoli–Cushman reaction; diastereoselectivity; homophthalic anhydride; indolenines; lactam synthesis; multicomponent reactions; Introduction The reaction of imines (prepared in a separate step

• [10]. The use of cyclic imines (or surrogates thereof such as isoquinoline [11]) in the CCR is quite scarce in the literature [12][13][14]. As an example, 1-pyrroline (in the form of its trimer 3) has been reported by Smith and co-workers [15][16][17] to condense efficiently with HPA analogs to

Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• reaction of monosubstituted o-phenylenediamines 11a,f–i with pyruvic ethyl ester (18a) or its acid 18b and postulated that an equilibrium between Z E imines 19, 20 and enamine 21 is quickly reached and the rate-determining reaction step is a subsequent intramolecular cyclization yielding the regioisomeric

• group in imines 2 shifts their tautomeric equilibrium to enamines 3. Selective synthesis of both 3,4-dihydroquinoxalin-2(1H)-one regioisomers 16e (SYN) and 17e (ANTI). The proposed mechanism for the synthesis of 3-methylquinoxalin-2(1H)-one regioisomers 22 and 23. In the case of starting 11g (Y: -H

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• ). During this study we observed common byproducts related to the reductive amination of sugars [19] (Scheme 1). All the reaction conditions tested (Table 1) showed the presence of alditol 4 as a result of sodium cyanoborohydride lack of selectivity [20] to reduce imines in the presence of aldehydes. When

New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized

• Maryna V. Murlykina,
• Maryna N. Kornet,
• Sergey M. Desenko,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Aleksander A. Brazhko,
• Vladimir I. Musatov,
• Erik V. Van der Eycken and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104

• basic. DMF increases solubility of imines 5, while the application of strong acid (HClO4) promotes Shiff bases protonation. Phenylpyruvic acid (1') was also applied as carbonyl component in GBB-3CR to obtain imidazopyrazoles having a carboxylic group. However, the process of decarboxylation took place

• imines 5 with impurities of the starting compounds were isolated when applying DMF with HClO4. Interestingly, in case of ethyl 2-isocyanoacetate (3b) the reaction proceeded equally well regardless of the substituent in the aldehyde. This can be connected with an increased reactivity of ethyl 2

• -isocyanoacetate (3b) compared to tert-butylisocyanide (3a) due to sterical reasons thus leveling the influence of the solubility factor of imines 5. As it has been already mentioned above, in contrast to 5-amino-N-aryl-1H-pyrazole-4-carboxamides 2, 3-amino-5-methylisoxazole (7) exhibited only properties of

New approach toward the synthesis of deuterated pyrazolo[1,5-a]pyridines and 1,2,4-triazolo[1,5-a]pyridines

• Aleksey Yu. Vorob’ev,
• Vyacheslav I. Supranovich,
• Gennady I. Borodkin and
• Vyacheslav G. Shubin

Beilstein J. Org. Chem. 2017, 13, 800–805, doi:10.3762/bjoc.13.80

• treating asthma and post-stroke patients [16]. 1,2,4-Triazolo[1,5-a]pyridines show antifungal [17], antitumor [18], and cytotoxic [19] activities. Both types of heterocyclic cores are readily available from N-aminopyridium salts and related pyridinium-N-imines via 1,3-cycloaddition reaction [20] or

• intramolecular ring closure [21][22][23][24]. The importance of these cores for medical chemistry studies suggests that isotopically labeled pyrazolo[1,5-a]pyridines and triazolo[1,5-a]pyridines could be of interest. Recently, deuterium-labeled pyridinium-N-imines were applied to mechanistic studies of the

• conversion to pyrazolo[1,5-a]pyridines [25][26]. Such labeled N-imines were obtained starting from commercially available pyridine-d5. Since substituted deuterated pyridines are less accessible new mild and simple methods of deuterium introduction into the pyridine ring are of great interest. The N

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

• Loïc Pantaine,
• Vincent Humblot,
• Vincent Coeffard and
• Anne Vallée

Beilstein J. Org. Chem. 2017, 13, 648–658, doi:10.3762/bjoc.13.64

• -terminated SAM with an aldehyde in solution or the condensation of an aldehyde-terminated SAM with an amine in solution [19]. These surfaces were stable in water but readily erased by acid-catalyzed hydrolysis at pH 3. The propensity of imines to be hydrolyzed under acidic conditions has also been harnessed

Synthesis of new pyrrolidine-based organocatalysts and study of their use in the asymmetric Michael addition of aldehydes to nitroolefins

• Alejandro Castán,
• Ramón Badorrey,
• José A. Gálvez and
• María D. Díaz-de-Villegas

Beilstein J. Org. Chem. 2017, 13, 612–619, doi:10.3762/bjoc.13.59

• organocatalysts with a bulky substituent at C2 were synthesized from chiral imines derived from (R)-glyceraldehyde acetonide by diastereoselective allylation followed by a sequential hydrozirconation/iodination reaction. The new compounds were found to be effective organocatalysts for the Michael addition of

• tuneable catalytic motifs to be used in organocatalysis starting from the chiral pool. Highly modular chiral aminodiol derivatives were obtained by the addition of organometallic reagents to chiral imines derived from (R)-glyceraldehyde – which is easily accessible from D-mannitol – and these were

• chiral pool, we have now focused on the synthesis of new chiral pyrrolidines capable of creating a sterically demanding environment due to the presence of a bulky 2,2-disubstituted-1,3-dioxolan-4-yl moiety at C2 from chiral imines derived from (R)-glyceraldehyde. The Michael addition of aldehydes to

Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

• Jan Szabo,
• Julian Greiner and
• Gerhard Maas

Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57

• the family of mesoionic five-membered heterocycles, of which the sydnones (1,2,3-oxadiazolium-5-olates), sydnone imines (1,2,3-oxadiazolium-5-aminides), and 1,3,4-thiadiazolium derived mesoionics are perhaps the best known members [25][26]. While not much is known about congeners of II, diverse

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• in 85–90% isolated yields. We also conducted similar reactions with cyclohexylamine and benzylamine instead of morpholine. In both cases, we ended up with the formation of corresponding imines (Table 1, entries 12 and 13). After the successful optimization, further extension of the reaction protocol

• . Furthermore, reactions with primary amines like cyclohexylamine and benzylamine produce only the imine and no A3-coupled product, signifying that imines are less efficient than iminium species to initiate further reaction with terminal alkyne. Conclusion In conclusion, the present study demonstrates an

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

• -Haloalkyllithiums are a useful class of organometallic reagents widely employed in synthetic chemistry. In fact, they allow the direct homologation of carbonyl compounds and imines leading to β-halo-alcohols and amines that are useful building blocks [29][30][31]. This work represents a remarkable example of flash

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• -membered heterocycles [2]. In addition, some cycloaliphatic thiocarbonyl S-methanides were shown to react with strongly electron-deficient cyano-substituted ethenes via zwitterionic intermediates to yield also seven-membered cyclic ketene imines, which easily undergo further conversions [3][4][5]. In the

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• ]. Opatz et al. developed the enantioselective syntheses of various alkaloids using the rhodium catalyst developed by Noyori [88] for the asymmetric transfer hydrogenation of imines. Interestingly, imines are formed from unstable α-aminonitrile intermediates which spontaneously eliminate HCN [89][90][91

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism

• which a >P(O)H species is added on the double bond of imines [11][12][13][14]. In this article, the latter pathway is utilized for the synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides. In most cases, the additions were carried out in the presence of a catalyst and solvent. The

• -transfer catalysts [25] were reported. The enantioselective hydrophosphonylation of imines was also described, where chiral catalysts were applied in various solvents [26][27][28][29][30][31][32]. There are a few examples, where the reactions were performed in a solvent in the absence of any catalyst [33

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• catalysts for aza-Diels–Alder reactions of Danishefsky’s diene with imines (Scheme 5) [52]. A variety of ammonium salts (L7–L10) including chiral cinchonidine derivatives L7 and catalyst L10 were found to promote the reaction in low-to-good yields albeit with no enantioselectivity. Although it is perhaps

• atoms covalently bonded to a benzylic carbon (Scheme 8). In 2016 Maruoka and Shirakawa followed up the aforementioned studies by demonstrating that tetraalkylammonium salts L5, L6, L11 and L12 as well as TBAI could activate imines toward aza-Diels–Alder reaction with Danishefsky’s diene (Scheme 9) [51

• imines with significantly greater reaction times than CF3(CF2)9I originally published by the Bolm group. As before, 1H NMR studies and calorimetric titration were used to validate the proposed halogen bond-based activation of substrates. Halogen bond-donor catalysis can be relevant to the processes in

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• allylation of a variety of active methylene compounds [29], aldehydes [30], ketones [31], and imines [32] with only common allylic alcohols. As part of an ongoing program studying the behavior of MBH derivatives [33] towards β-dicarbonyl compounds, our research group [34][35][36][37] has reported an

Chiral ammonium betaine-catalyzed asymmetric Mannich-type reaction of oxindoles

• Masahiro Torii,
• Kohsuke Kato,
• Daisuke Uraguchi and
• Takashi Ooi

Beilstein J. Org. Chem. 2016, 12, 2099–2103, doi:10.3762/bjoc.12.199

• stability arising from the aromatic character. Accordingly, a number of catalytic methods are available for the asymmetric functionalization of oxindole enolates with various different electrophiles. However, successful examples of Mannich-type reactions with imines are surprisingly limited despite allowing

• substantial decrease in diastereoselectivity was observed in the reaction with 2-furyl aldimine 3h, owing to the requisite higher reaction temperature (Table 2, entries 6 and 7). Catalysis with 1c was also applicable to aliphatic imines, which required prolonged reactions and slightly higher catalyst loadings

Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

• Lena Huck,
• Juan F. González,
• Elena de la Cuesta and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2016, 12, 1772–1777, doi:10.3762/bjoc.12.166

• direct aziridination of an olefin [14] or the reaction of an imine with diazoalkanes. Alternatively, the reaction of imines with various nucleophiles, including aza-Darzens mechanisms, can lead to aziridine products [15]. However, few known methods allow the synthesis of C-trisubstituted aziridines

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

• Motoyuki Isoda,
• Kazuyuki Sato,
• Yurika Kunugi,
• Satsuki Tokonishi,
• Atsushi Tarui,
• Masaaki Omote,
• Hideki Minami and
• Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

• asymmetric Mannich reaction using a Lewis acid catalyst [1]. (L)-Proline is known as an excellent promoter for the Mannich reaction [2][3][4][5][6], and besides this, the reaction of the silyl enol ether derivatives with imines was used as an effective method [7][8][9]. In this situation, a wide variety of

• Mannich-type reactions have been reported to give β-amino esters and/or β-lactams by using metal enolates [10][11][12][13][14][15][16][17]. In contrast, most of reductive Mannich-type reactions using imines and α,β-unsaturated carbonyl compounds gave β-amino esters, but there are only a few reports for a

• direct synthesis of β-lactams by reductive Mannich-type reactions [14][18][19][20][21]. We recently reported a reductive Mannich-type reaction using a combination of RhCl(PPh3)3 and Et2Zn to give the corresponding syn-β-lactams from α,β-unsaturated esters and imines in good to excellent yields together

Enantioselective addition of diphenyl phosphonate to ketimines derived from isatins catalyzed by binaphthyl-modified organocatalysts

• Hee Seung Jang,
• Yubin Kim and
• Dae Young Kim

Beilstein J. Org. Chem. 2016, 12, 1551–1556, doi:10.3762/bjoc.12.149

• reaction time, and low temperature required for good enantioselectivity. Thus, new approaches for the organocatalytic enantioselective addition of diphenyl phosphonate to isatin imines are highly desired. In connection with our ongoing research program on the design and application in asymmetric catalysis

• ). The reaction of diphenyl phosphonate (2) with N-allylated and 5-halo-N-allylated isatin imines provided adducts 3a–d in good yields (80–94%) with excellent enantioselectivities (93–97% ee, Table 2, entry 1–4). The addition of diphenyl phosphonate (2) to 5-chloro-N-substituted isatin imines 1e and 1f

• provided 3-amino-3-phosphonyl-substituted oxindole derivatives 3e and 3f in high yields (84% and 70%) with good enantioselectivities (99% ee and 88% ee, Table 2, entries 5 and 6). N-Benzylisatin imine 1g and 5-halogen-N-benzylisatin imines 1h–j reacted well with diphenyl phosphonate (2), giving 3-amino-3

Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

• Erika Bálint,
• Ádám Tajti,
• Anna Dzielak,
• Gerhard Hägele and
• György Keglevich

Beilstein J. Org. Chem. 2016, 12, 1493–1502, doi:10.3762/bjoc.12.146

• step is the nucleophilic addition of diethyl phosphite to the C=N bond of the imines resulting in phosphonates III or IV, respectively. Then, the elimination of an amine or ethanol and the addition of another unit of diethyl phosphite may lead to (aminomethylene)bisphosphonates (VI). If the amine is in