Recent synthesis of thietanes

• Jiaxi Xu

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

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• with a tributylstannyl group to give 133 was accomplished by the reaction with (Bu3Sn)2CuLi in THF at −78 °C. The reaction took place following an addition–elimination mechanism. Then, coupling of 133 with iodobenzene in the presence of Pd(PPh3)4 and CuI as the co-catalyst afforded ethyl (E)-3-phenyl-3

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• a yield of 86%, the pyrazolo derivative 10p could only be obtained in a moderate yield of 38%. This might be explained by the tendency of the pyrazolo moiety to act as a leaving group and a following addition–elimination reaction with methanol can take place (the corresponding 2-methoxy-substituted

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• in the reaction of thiourea with primary amines [6]. Another important synthetic route for substituted thioureas is a two-step approach: (i) the addition/elimination reaction of benzoyl chloride, with a thiocyanate salt, generating in situ, benzoyl isothiocyanate, and (ii) an appropriate amine

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

• /Cvinyl–CF2H bonds followed a radical addition–elimination process (Scheme 73). Subsequently, Bouyssi and co-workers [135][136][137] used Togni’s reagent to conduct the trifluoromethylation of (hetero)aromatic aldehydes or corresponding N,N-dialkylhydrazones with CuCl as the catalyst at room temperature

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives

• Peng Li,
• Yongqi Wu,
• Tingting Zhang,
• Chen Ma,
• Ziyun Lin,
• Gang Li and
• Haihong Huang

Beilstein J. Org. Chem. 2019, 15, 703–709, doi:10.3762/bjoc.15.65

• Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, P. R. China 10.3762/bjoc.15.65 Abstract A highly efficient and convenient protocol was developed to access 2-amino-4H-benzothiopyran-4-ones through a process of conjugated addition–elimination. The sulfinyl group was proved to

• good yields and excellent chemical purity without requiring column chromatographical purification. Keywords: 2-amino-4H-benzothiopyran-4-ones; addition–elimination; scale-up synthesis; sulfinyl group; Introduction Benzothiopyranones are a class of molecules displaying biological activities in part

• group to afford the desired 2-amino-4H-benzothiopyran-4-ones through conjugated addition–elimination by nucleophiles. Subsequently, substrates 2a and 3a were reacted with a variety of alkyl/arylamines in the optimized solvent isopropanol (Table 2). Substrate 2a having an ethylsulfinyl group in general

Transition metal-free oxidative and deoxygenative C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyl lithium as an efficient synthetic approach to azaheterocyclic carboranes

• Lidia A. Smyshliaeva,
• Mikhail V. Varaksin,
• Pavel A. Slepukhin,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2018, 14, 2618–2626, doi:10.3762/bjoc.14.240

• considered as nucleophilic substitution of hydrogen (SNH) in non-aromatic N-oxides of 2H-imidazoles 1a–d. It has also been shown that the SNH reactions can be realized via either an "addition–elimination" SNH(AE) mechanism, or through an "addition–oxidation" SNH(AO) scheme to form imidazolyl carbonanes 4a–d

• carboranyllithium, generated in situ from commercially available o-carborane. It has also been found that the SNH(AE, «addition–elimination») scheme leads to carboranyl-substituted 2H-imidazoles, while alternative SNH(AO, «addition–oxidation») results in the corresponding N-oxide analogues. In summary, novel

• -oxides 1a–d and carboranyl lithium 2. The reactions were carried out in accordance with the optimized coupling conditions according to the "addition–elimination" SNH(AE) or "addition–oxidation" SNH(AO) pathways (Table 1 and Table 2). Optimization of the reaction conditions for the C–H/C–Li cross-coupling

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• literature data and our experimental observations. N-Aryl-3,4-dihydroquinazolines 1. Reaction intermediate in the synthesis of compound 2a. Synthetic pathway leading to N-aryl-3,4-dihydroquinazolines 1. Synthesis of compounds 2. Addition–elimination mechanism for the heterocyclization. Proposed mechanism

Enzyme-free genetic copying of DNA and RNA sequences

• Marilyne Sosson and
• Clemens Richert

Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47

• extension occurs as expected, most probably via addition/elimination, including a pentavalent intermediate and possibly by a pseudorotation to place the ethylimidazole leaving group in an apical position. Since either of the two alcohols of the terminal diol of the primer can attack, a mixture of 3',5'- and

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• -keto ester 6 could be prepared by an addition–elimination reaction of commercially available tetrafluorosuccinic acid diester 7. The designed reaction protocol enabled the construction of the target multicyclic molecules in only five or six steps, which is a more efficient protocol with three reaction

• -step manipulations for obtaining the CF2CF2-containing multicyclic molecules 1 and 2. Scope and limitation The synthetic route was initiated by the sequential addition–elimination reaction of 4-n-propylphenylmagnesium bromide (4-n-PrC6H4MgBr) with commercially available dimethyl tetrafluorosuccinate (7

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• ; Introduction As 1,1-difluoro-1-alkenes have an electron-deficient carbon–carbon double bond, they readily undergo intramolecular substitution of nucleophiles through an addition–elimination mechanism [1][2]. Thus, under basic conditions, they serve as useful precursors for ring-fluorinated heterocycles and

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• hydrazide took part in the reaction in CH2Cl2 solution at room temperature, and after the addition–elimination sequence, the corresponding enehydrazide, analogous to enamines 53/54, was obtained in 56% yield [63]. The configuration of this enehydrazide has not been proved, but the course of its

• , such as 1,2-diamines and β-aminoalcohols are of special importance as they offer access to a variety of heterocycles through an addition–elimination–heterocyclization sequence. Their ability to act as single-electron acceptors, demonstrated in the reaction with thiols and selenols, allows their

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

• an unique hydride-donor reactivity [82]. An addition–elimination mechanism has been previously proposed for the LiAlH4 promoted decyanation of 2,2-diphenylpropionitrile and related nitriles. In such pathways, the phenyl groups probably favor the C–C bond cleavage by stabilizing the incipient negative

• reductive decyanation Among the other procedures mentioned in our previous review [9], the base [129][130] or acid-induced [131][132][133][134] hydrolysis–decarboxylation sequence appears as a classical pathway (Scheme 28). In the particular case of diphenylacetonitriles, an addition–elimination mechanism

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• radicals to make transient imines [1][2][3]. In turn, onward reactions of the imines provide assorted products including ketones and nitrogen heterocycles [4][5][6][7][8][9][10]. Figure 1a shows a generic addition/elimination reaction of ene-sulfonamides along with example transformations in Figure 1b from

Selenium halide-induced bridge formation in [2.2]paracyclophanes

• Laura G. Sarbu,
• Henning Hopf,
• Peter G. Jones and
• Lucian M. Birsa

Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266

• Analytical Chemistry, Technical University of Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany 10.3762/bjoc.10.266 Abstract An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene

• synthetic procedure involves an addition/elimination protocol of selenium derivatives, the formation of isomeric endo-exo-dienes 2, 3 and 5, 6 resembles the zig-zag cyclizations of nonconjugated cyclic diynes of medium ring size reported by Gleiter [31][32]. In order to check the limits of these selenium

• additional support to the proposed reaction mechanism, as only diene 13, along an equimolar amount of diphenyl diselenide, was obtained (Table 2, entry 3). Conclusion We present here an addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes that

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• and in a diastereoselective transformation. This transformation generates one C–C and one C–N bond and presumably proceeds via a reaction sequence comprising a Michael-type addition–elimination reaction, a nucleophilic attack of an enamine to a carbonyl reminiscent of one of the steps of the Bayllis

• . An initial Michael addition–elimination reaction, leading to the exchange between the starting arylamine 3 and dimethylamine, explains the formation of intermediates 4, which were the final reaction products in most investigated solvents. However, in DMF, the enamine moiety of 4 attacks the aldehyde

• transformation occurs via a domino sequence of reactions, which generates one C–C and one C–N bond. Presumably, this transformation proceeds via a reaction sequence comprising a Michael-type addition–elimination reaction, a nucleophilic attack of an enamine to a carbonyl, and a final deoxygenation step. We

Flow microreactor synthesis in organo-fluorine chemistry

• Hideki Amii,
• Aiichiro Nagaki and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2013, 9, 2793–2802, doi:10.3762/bjoc.9.314

• stepwise manner via an addition–elimination pathway. However, it is difficult to synthesize unsymmetrical diarylethenes with conventional macro batch systems because of contamination of the symmetrical diarylethenes (two identical nucleophiles are incorporated at the same time). Integrated flow

• microreactor synthesis of photochromic diarylethenes was found to be effective; the generation of heteroaryllithiums and the subsequent nucleophilic addition/elimination with octafluorocyclopentene were successfully achieved (Scheme 12) [75]. As a significant progress, the selective synthesis of unsymmetrical

• by nucleophilic substitution reactions using [18F]-fluoride ion (Scheme 7) [55][56][57][58][59][60][61][62][63][64][65][66][67]. For not only fluorination/fluoroalkylation, but also for defluorination, flow microreactor synthesis is quite effective. Defluorination involving a nucleophilic addition

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• intramolecular addition–elimination reaction. In the presence of the aldehyde 154, 153 underwent a Horner–Wittig reaction to generate 155 as a 1:2.3 mixture of E- and Z-isomers. Treatment of 155 with boron trichloride not only liberated the phenol but also isomerized the E-double bond to the Z-isomer. Finally, a

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• involving 3, which could be rationalized by the mechanism shown in Scheme 3. Because of the high oxidation power of NO3•, it is proposed that the reaction is initiated by ET at the aromatic ring through an addition–elimination pathway, as has been suggested from time-resolved transient spectroscopic studies

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• through a second radical reaction with dichlorovinyl ethylsulfone (132) [54]. The ethylsulfonyl radical created in the addition–elimination process of intermediate radical 133 fragments to liberate sulfur dioxide and an ethyl radical that is capable of propagating the chain. The resulting product 134

Synthesis of SF₅-containing benzisoxazoles, quinolines, and quinazolines by the Davis reaction of nitro-(pentafluorosulfanyl)benzenes

• Petr Beier and
• Tereza Pastýříková

Beilstein J. Org. Chem. 2013, 9, 411–416, doi:10.3762/bjoc.9.43

• Davis and Pizzini [7] and probably proceeds through the formation of σH adducts that give nitroso compounds, which upon deprotonation enter an intramolecular addition–elimination process as shown in Scheme 1. Typical reaction conditions are an excess of alkali metal hydroxide in a low-boiling-point

Highly stereocontrolled synthesis of trans-enediynes via carbocupration of fluoroalkylated diynes

• Tsutomu Konno,
• Misato Kishi and
• Takashi Ishihara

Beilstein J. Org. Chem. 2012, 8, 2207–2213, doi:10.3762/bjoc.8.249

• 1.5 equiv of potassium tert-butoxide (t-BuOK) in THF at room temperature for 2 h. Very surprisingly, the desired trifluoromethylated diyne 4a was not detected at all and the addition–elimination product 5a was obtained quantitatively. Therefore, we examined the reaction conditions for the β

Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions

• Lukas Kupracz,
• Jan Hartwig,
• Jens Wegner,
• Sascha Ceylan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168

• ). The stereochemical outcome of this addition–elimination process may be rationalized by assuming an anti-addition of iodine azide onto the π-bond. After rotation along the C–C σ-bond (3h to 3h') anti-orientation of the proton and iodine allows for facile base-mediated elimination. This results in

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• difficulties: The low reactivity of β,β-disubstituted Michael receptors, the difficulty in controlling π-facial stereoselectivity, and the equilibrium of stereoisomers through an addition/elimination mechanism. The reduced reactivity of β,β-disubstituted Michael receptors towards nucleophilic addition is