Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

• Manuel Pedrón,
• Laura Legnani,
• Maria-Assunta Chiacchio,
• Pierluigi Caramella,
• Tomás Tejero and
• Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

• -mediated oxidation of tertiary amines [26] by trapping them with cyanide anion [27][28]. These results point out the formation of transient carbocations III that can be stabilized by the presence of heteroatoms in the alpha position. The formation of transient carbocations do not contradict, necessarily

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

• that the amine could play a role in promoting the [2,3]-sigmatropic rearrangement. After a screening of different tertiary amines, Rubin et al. found that DBU could be used as a base in the phosphinylation reaction but also as an efficient catalyst for the subsequent [2,3]-sigmatropic rearrangement of

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

• from the less hindered and more reactive, less substituted position of its two canonical forms. In a similar manner, Rueping et al. demonstrated the functionalisation of C–H bonds α to tertiary amines with various nucleophiles. They also reported the formation of C–C bonds from α-amino C–H bonds using

Nucleophilic fluoroalkylation/cyclization route to fluorinated phthalides

• Masanori Inaba,
• Tatsuya Sakai,
• Shun Shinada,
• Tsuyuka Sugiishi,
• Yuta Nishina,
• Norio Shibata and
• Hideki Amii

Beilstein J. Org. Chem. 2018, 14, 182–186, doi:10.3762/bjoc.14.12

• synthesis of 1, we carried out the nucleophilic trifluoromethylation of 2 employing a small amount of chiral tertiary amines. However, the use of (1R,2R)-(N,N,N’,N’-tetramethyl)-1,2-diaminocyclohexane (8) as a chiral catalyst resulted in the formation of a racemic mixture of 1a (Table 2, entries 1 and 2

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• nanoscale MoS2. The scope of the reaction is quite similar to Li’s report [60]. The photocatalyst nanocomposite was reused in eight consecutive cycles with only slight decrease in activity. Yadav et al. developed a metal-free photoredox-catalyzed α-C(sp3)–H thiocyanation reaction for tertiary amines (Scheme

•  28) [63]. The reaction mechanism is different from the previous examples. The photoexcited state of Eosin Y can be quenched reductively by tertiary amines to form an Eosin Y radical anion and an amine radical cation. Molecular oxygen regenerates Eosin Y and is reduced to its superoxide radical anion

• photooxidized tertiary amines under aerobic conditions to the respective radical cationic species (Scheme 53) [91]. Further steps lead to an enamine intermediate, which can react with the former generated sulfonyl radical. They were able to apply a series of electronically and sterically differing (hetero

Diastereoselective Mannich reactions of pseudo-C₂-symmetric glutarimide with activated imines

• Tatsuya Ishikawa,
• Tomoko Kawasaki-Takasuka,
• Toshio Kubota and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 2473–2477, doi:10.3762/bjoc.13.244

• lactones in good to excellent yields [4][5]. One of the most intriguing features of this protocol is the fact that the enantiomers at the lactone part were readily obtained only by the selection of the tertiary amines employed in the reaction. It is quite apparent that this success is, at least in part

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

• tertiary amines), while the use of stronger bases (hydroxides or alkoxides) caused decomposition of the base-sensitive 1H-pyrrole-2,3-dione moiety 9. An attempt to perform the reaction in the presence of catalytic amounts of Brønsted acid (TsOH) also did not provide the spirocyclic products. Instead

Sustainable synthesis of 3-substituted phthalides via a catalytic one-pot cascade strategy from 2-formylbenzoic acid with β-keto acids in glycerol

• Lina Jia and
• Fuzhong Han

Beilstein J. Org. Chem. 2017, 13, 1425–1429, doi:10.3762/bjoc.13.139

• efficiency of the reaction, a detailed optimization study was performed with various bases, such as tertiary, secondary and primary amines. When tertiary amines were used as the catalyst, very low yields of 3a were obtained (Table 1, entries 3–5). Unfortunately, a sluggish reaction was observed in the

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• strategies with chiral transition metals [27][28][29][30][31][32][33], organocatalysts such as secondary amines [34][35][36], nucleophilic phosphines [26][37][38][39][40][41][42][43][44], tertiary amines [45], N-heterocyclic carbenes (NHCs) [46][47][48], and cinchona alkaloid derivatives [25][28][49][50

Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

• Maximilian Maier,
• Magnus S. Schmidt,
• Markus Ringwald and
• Christoph P. Fik

Beilstein J. Org. Chem. 2017, 13, 372–383, doi:10.3762/bjoc.13.40

• could isolate crude diamines 8 and 9, containing significant amounts (10–15%) of the tertiary amines 8a and 9a (Scheme 3) or diamine 16, respectively; each could be used without further purification. Classical acylation with acetyl chloride or acryloyl chloride in the presence of triethylamine led to

• responsible for this effect, we decided to use 1,4-diaminobutane (13) and allyl chloride for the synthesis of diamine 11. This also resulted in the positive side effect, that a formation of tertiary amines, comparable to compounds 8a and 9a, is not possible in this case. Interestingly, during the addition of

Orthogonal protection of saccharide polyols through solvent-free one-pot sequences based on regioselective silylations

• Serena Traboni,
• Emiliano Bedini and
• Alfonso Iadonisi

Beilstein J. Org. Chem. 2016, 12, 2748–2756, doi:10.3762/bjoc.12.271

• excess of several bases (Table 1). In all cases 6-O-silylated derivative 2 was obtained as the main product, but yields and rates were strongly dependent on the adopted base: pyridine (Table 1, entries 6–9) gave much better results than tertiary amines (Table 1, entries 1–5) that, on the other hand, had

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• ][21][22][23][24][25][26][27][28][29][30][31][32][33][34], have not been prepared so far. In the present work, we focused on the development of a general approach to tertiary amines and polyamines bearing several hydrazonomethyl arms at the nitrogen atom(s). To achieve this goal, we suggested a

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• tertiary amines (1.467(2) and 1.476(2) Å), resulting in a slight distortion of the ring and nitrogen plane. Conclusion We have described an operationally simple synthetic procedure for the N-tetraalkylation of cyclam (1) and cyclen (2) with a range of hydrophobic functional groups. This procedure affords

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II)-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

• Valerij A. Nikolaev,
• Jury J. Medvedev,
• Olesia S. Galkina,
• Ksenia V. Azarova and
• Christoph Schneider

Beilstein J. Org. Chem. 2016, 12, 1904–1910, doi:10.3762/bjoc.12.180

• this process apparently plays the Rh-complex, since it is known that without a catalyst a cleavage of tertiary amines of this kind in the presence of oxygen does not occur [30]. It is conceivable as an alternative that the occurrence of amide 7 is derived from the oxidation of the Wolff rearrangement

Potent triazine-based dehydrocondensing reagents substituted by an amido group

• Munetaka Kunishima,
• Daiki Kato,
• Nobu Kimura,
• Masanori Kitamura,
• Kohei Yamada and
• Kazuhito Hioki

Beilstein J. Org. Chem. 2016, 12, 1897–1903, doi:10.3762/bjoc.12.179

• (NMM). Related triazinylammonium salts (DMT-Am) can be prepared from other tertiary amines 5 instead of NMM (Scheme 1c) [6]. Since the direct reaction of carboxylates with CDMT is very slow, the formation of DMT-Am is essential for the conversion of carboxylates into 4 [7]. Therefore, we developed

• catalytic amide-forming reactions in water using triazinylammonium salts (DMT-Am) generated in situ from CDMT and a catalytic amount of tertiary amines 5 (Scheme 1d). Most notably, by introducing various functional groups into 5, it was possible to develop a cyclodextrin-based artificial acyltransferase [7

• recognitions of carboxylic acids were affected by fuctionalized DMT-Am. However, once the reaction with 1 takes place, the functionalized tertiary amines 5 liberated, no longer affect the following reaction (Scheme 1d). As a consequence, the resulting acyloxyatriazine intermediate 4, which is the same

Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

• Barbara Dmochowska,
• Karol Sikora,
• Anna Woziwodzka,
• Jacek Piosik and
• Beata Podgórska

Beilstein J. Org. Chem. 2016, 12, 1434–1439, doi:10.3762/bjoc.12.138

• methanol, an alternative route involving the reaction of 6-bromohexyl D-glucopyranoside (2′ [32] or 3′) with tertiary amines (trimethylamine in ethanol and with pyridine) was applied; the yields were of 90–94%. Shifting the pyranose leaving group (halogen) by six carbon atoms from C1 makes it easier to

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• -workers explored the ability of chiral tertiary amines to catalyze the enantioselective addition of thiols to α-aminoacrylates (Scheme 5) [22]. The authors found that quinidine (21) catalyzed the enantioselective addition of benzylmercaptan (19) to α-aminoacrylate 20 in modest enantioselectivity

Stereoselective amine-thiourea-catalysed sulfa-Michael/nitroaldol cascade approach to 3,4,5-substituted tetrahydrothiophenes bearing a quaternary stereocenter

• Sara Meninno,
• Chiara Volpe,
• Giorgio Della Sala,
• Amedeo Capobianco and
• Alessandra Lattanzi

Beilstein J. Org. Chem. 2016, 12, 643–647, doi:10.3762/bjoc.12.63

• diastereoisomeric tetrahydrothiophenes were observed when using tertiary amines such Et3N, DBU or TMG [21][22]. At the outset, the sulfa-Michael/nitroaldol reaction was studied by reacting trans-β-nitrostyrene, (E)-1-phenyl-2-nitropropene and (E)-1-phenyl-2-nitrobutene in toluene at room temperature with 1,4

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• associated with adding two different nucleophiles and simultaneously eliminates the need for an external oxidant. Particularly advantageous is the direct addition of electron-rich amino groups, especially tertiary amines, which are difficult to access by other known methods. Furthermore, O-acylhydroxylamines

• variety of 1,2-oxyamino products in a modular manner with excellent regioselectivity. It offers an appealing oxyamination method, especially for the construction of electron-rich tertiary amines. Future efforts will be undertaken for a better understanding of the reaction mechanism and for the development

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

• ] reported the copper-catalyzed, tert-butyl hydroperoxide (TBHP)-assisted C–H amidation of tertiary amines 1. By heating at 80 °C, the C–H bond in dimethylaniline underwent direct amidation to provide products 3 in the presence of amides 2. On the other hand, the dephenylation transformation via C–C bond

• from the chemistry related to the C–H amidation. Copper-catalyzed C–H amidation of tertiary amines. Copper-catalyzed C–H amidation and sulfonamidation of tertiary amines. Copper-catalyzed sulfonamidation of allylic C–H bonds. Copper-catalyzed sulfonamidation of benzylic C–H bonds. Copper-catalyzed

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines

• donor precursors Hoffmann and co-workers demonstrated that tertiary amines N(CH2R)3 were suitable donors, transferring their N-lone pair electrons to photoexcited TiO2, CdS or ZnS thus generating aminium radical cations +•N(CH2R)3. These deprotonated at an adjacent C-atom to furnish α-aminoalkyl

• isolated in a good yield but the process was less effective with 6- and 7-membered rings (Scheme 4). When the water in these amine reactions was replaced by alcohols, photolyses with Pt-TiO2 led to coupling and the formation of the corresponding secondary or tertiary amines; for example 20 (Scheme 4) [49

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• corresponding acetylated (hetero)arenes which are easily accessible reagents, including commercially available ones. It is well known that the reaction of isatins 7 with methyl ketones 8 leads to the formation of aldol-type adducts 9 under catalysis with mild bases, such as secondary or tertiary amines. These

Hydrogenation of unactivated enamines to tertiary amines: rhodium complexes of fluorinated phosphines give marked improvements in catalytic activity

• Sergey Tin,
• Tamara Fanjul and
• Matthew L. Clarke

Beilstein J. Org. Chem. 2015, 11, 622–627, doi:10.3762/bjoc.11.70

• tetrasubstituted enamines. The use of the sustainable and environmentally benign solvent (R)-limonene for the reaction is also reported with the amine isolated by acid extraction. Keywords: alkenes; homogeneous catalysis; hydrogenation; renewable solvents; tertiary amines; Introduction A potentially very direct

• method to produce tertiary amines is by the hydrogenation of enamines. While the hydrogenations of enamides, bearing coordinating acyl substituents is probably the most developed and studied of all hydrogenation processes, studies on the hydrogenation of unactivated enamines are scarce and several

• triacetoxyborohydride or sodium cyanoborohydride can be appealing at small scale where the practical issues noted above are not so important. However, the formation of tertiary amines from aryl ketones using hydride reagents has been reported to be problematic [31]. In addition, the hydride reductions, whether carried

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• the area of visible light photoredox reactions. Visible-light-induced sp3 C–H bond functionalization of tertiary amines. Substrate scope for aerobic oxidative cyclization of N,N-dimethylanilines with maleimides. A proposed reaction mechanism. Screening and control experimentsa. Optimization of

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13