Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• =CH]-Gly isosteres, a SN2’ reaction upon 3,3-difluoropropene substrates can be used, as shown by Taguchi’s group. The synthesis of monofluoroalkenes starting from 3,3-difluoropropenes and using trialkylaluminium reagents was developed. Using this methodology, they were able to prepare Boc-Nva-ψ[CF=CH

• ]-Gly isostere [26] via a SN2’ reaction (Scheme 3). The defluorinative allylic alkylation of terminal 3,3-difluoropropene 10 with triethylaluminium selectively provided the corresponding (Z)-monofluoroalkene 11. In this case, the use of Et3Al allowed access to a norvaline (Nva) isostere. Then, alcohol

• reacted easily in a SN2 reaction to give a more functionalized molecule. For example, treatment of the chlorinated monofluoroalkene with NaN3 provided the corresponding N3-containing monofluoroalkene. The azide group underwent a 1,3-dipolar cycloaddition to give a 1,2,3-triazole, which is also a peptide

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

• . Computational section To elucidate reasons for the observed regioselectivities, the reactions of uracil and 7,8-dimethylalloxazine with benzylamine and ethyl bromide were studied by DFT calculations using the B3LYP/6-311+G**//B3LYP/6-31G*+ZPVE method. The transition-state calculations of the SN2 reaction of

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• less time-consuming and more cost-efficient synthesis. Commercially available, inexpensive 4,5-dimethylthiazole is used as azole starting material instead of 4-aryl-1,2,4-triazoles. The precursor 1a for the NHC ancillary ligand is synthesized via a double SN2-reaction of two equivalents of thiazole

Unusual traits of cis and trans-2,3-dibromo-1,1-dimethylindane on the way from 1,1-dimethylindene to 2-bromo-, 3-bromo-, and 2,3-dibromo-1,1-dimethylindene

• Rudolf Knorr,
• David S. Stephenson,
• Ernst Lattke,
• Petra Böhrer and
• Jakob Ruhdorfer

Beilstein J. Org. Chem. 2016, 12, 1178–1184, doi:10.3762/bjoc.12.113

• of solid KOt-Bu, which consumed 6 within less than 2 hours at rt. Aqueous work-up with Et2O afforded the dibromide 7 (29 mg, 87%) as the only product (hence, no SN2 reaction by KOt-Bu). NEt3 as the base in place of KOt-Bu required 12 days at rt. c) From 1,1-dimethylindane (9): A mixture of N

A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

• Oksana S. Mikhalchenko,
• Dina V. Korchagina,
• Konstantin P. Volcho and
• Nariman F. Salakhutdinov

Beilstein J. Org. Chem. 2016, 12, 648–653, doi:10.3762/bjoc.12.64

• may undergo stereoselective trap by H2O to form alcohol epimers 2; these may then undergo a stereospecific SN2 reaction to form fluoride epimers 8; c) the fluorination and/or hydroxylation of cation 10, forming fluoride epimers 8 and alcohol epimers 2, respectively, may be reversible. This has several

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• only recently [86]. Solventless mechanochemical reactions are usually highly efficient and selective, valuable properties exploitable in CD derivatization. Nucleophilic substitutions (SN2 reaction) may occur without solvent stabilization because charged species do not need to be formed in the

• excluded. A good example of a mixed reaction mechanism is the glycosylation reported by Tyagi et al. [88], where SN2 glycosylation seems to be dominant, with no neighbouring group participation, which is typical of glycosylation reactions of activated acetylated carbohydrates. A more pure SN2 reaction is

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

Synthesis of phosphoramidites of isoGNA, an isomer of glycerol nucleic acid

• Keunsoo Kim,
• Venkateshwarlu Punna,
• Phaneendrasai Karri and
• Ramanarayanan Krishnamurthy

Beilstein J. Org. Chem. 2014, 10, 2131–2138, doi:10.3762/bjoc.10.220

• proved problematic and no product was detected. Therefore, in the adenine case, we tried a direct SN2 reaction of N6-benzoyladenine with tosyl derivative 6, which was only moderately successful (30% yield of 7). Unexpectedly, in both the thymine and adenine cases, the subsequent debenzylation reaction

• protecting group approach. We silylated 1 to afford 8 whose ketal was deprotected followed by tritylation to give the derivative 10, which is expected to be suited for the introduction of nucleobases by an SN2 reaction (Scheme 2). Once again, the Mitsunobu reaction with thymine proceeded smoothly. However

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• -RC reaction between the α,β-unsaturated imine and the enolate, followed by an SN2 reaction. 2.14 Annulations through double-Michael additions The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient alkynes provides an efficient approach for the synthesis of

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• ). An SN2 reaction with 5 [55] led to 8. We abandoned our initial shorter synthetic route based on a Mitsunobu reaction leading from 6 directly to 8 due to severe purification difficulties. Compound 8 could be charge-tagged to 9 using ethyl bromide. Finally, the free catalyst 1 was obtained by acidic

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

• Mahesh K. Lakshman,
• Manish K. Singh,
• Mukesh Kumar,
• Raghu Ram Chamala,
• Vijayender R. Yedulla,
• Domenick Wagner,
• Evan Leung,
• Lijia Yang,
• Asha Matin and
• Sadia Ahmad

Beilstein J. Org. Chem. 2014, 10, 1919–1932, doi:10.3762/bjoc.10.200

• mechanisms were proposed, namely reaction of the carboxylate at the phosphorus center (equivalent to pathway a in Scheme 3) or a SN2’ reaction at the N3 atom (equivalent to pathway b in Scheme 3) [34]. Experiments with [18O]-labeled benzoate indicated that conversion of carboxylic acids to the acyl HOBt

One-pot stereoselective synthesis of α,β-differentiated diamino esters via the sequence of aminochlorination, aziridination and intermolecular S_N2 reaction

• Yiwen Xiong,
• Ping Qian,
• Chenhui Cao,
• Haibo Mei,
• Jianlin Han,
• Guigen Li and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 1802–1807, doi:10.3762/bjoc.10.189

Orthogonal dual thiol–chloroacetyl and thiol–ene couplings for the sequential one-pot assembly of heteroglycoclusters

• Michele Fiore,
• Gour Chand Daskhan,
• Baptiste Thomas and
• Olivier Renaudet

Beilstein J. Org. Chem. 2014, 10, 1557–1563, doi:10.3762/bjoc.10.160

• alkyne–azide cycloaddition (CuAAC) [18] or SN2 reaction [19]. In addition, orthogonal chemoselective ligations were proved more attractive strategies to prepare hGCs in high yields, in part because they require less synthetic and purification steps. For example, oxime and CuAAC ligations have been used

Regioselective S_N2' Mitsunobu reaction of Morita–Baylis–Hillman alcohols: A facile and stereoselective synthesis of α-alkylidene-β-hydrazino acid derivatives

• Silong Xu,
• Jian Shang,
• Junjie Zhang and
• Yuhai Tang

Beilstein J. Org. Chem. 2014, 10, 990–995, doi:10.3762/bjoc.10.98

• –Hillman; SN2' reaction; Introduction Hydrazines and their derivatives are an important class of compounds in organic chemistry. They are widely used in the fields of pesticides, polymers, dyestuff, and pharmaceutical agents [1]. They are also versatile building blocks for accessing many important

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• at the reaction center was prepared by the use of Z matrices. For instance, in the gas phase SN2 reaction Cl− + H3C–Br → Cl–CH3 + Br−, Cl···C and C···Br intermediate distances were assumed. The geometry was optimized under the constraint of the fixed Cl–C and C–Br distances. After the partial

Triol-promoted activation of C–F bonds: Amination of benzylic fluorides under highly concentrated conditions mediated by 1,1,1-tris(hydroxymethyl)propane

• Pier Alexandre Champagne,
• Alexandre Saint-Martin,
• Mélina Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2013, 9, 2451–2456, doi:10.3762/bjoc.9.283

• the reaction are currently underway in our laboratory. SN2 reaction of activated alkyl fluorides and calculated transition state for the reaction of morpholine with benzyl fluoride with three molecules of water. Proposed activation of C–F bonds mediated by a triol. Initial screening. Fine-tuning

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• undesired side-product formation and, consequently, a lower yield. Therefore, the choice of the right solvent and reaction conditions is the key to the success of this transformation. Our initial attempts focused on the synthesis of azido derivatives in MeCN. Although generally performed in DMF, the SN2

• reaction of alkyl bromide with NaN3 can also be performed in MeCN. NaN3 is insoluble in MeCN at room temperature (<0.005 g/100 mL), but its solubility increases at higher temperatures. Furthermore, NaBr generated during the nucleophilic substitution is insoluble and can be removed by filtration as can the

Kinetics and mechanism of the anilinolysis of aryl phenyl isothiocyanophosphates in acetonitrile

• Hasi Rani Barai and
• Hai Whang Lee

Beilstein J. Org. Chem. 2013, 9, 615–620, doi:10.3762/bjoc.9.68

• congestion in the bond-making process in a stepwise process with a rate-limiting bond formation (or a normal SN2 reaction) [13][14][15]. The magnitudes of the kH/kD values invariably decrease as the aniline becomes less basic. The magnitudes of the kH/kD values invariably increase for X = (4-MeO, 4-Me, H, 4

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• coming close to a general route to introduce functionality into bisallenes at the present time seems to be the double SN2'-reaction of 2,4-hexadiyne-1,6-diol (63, e.g. R1 to R4 = aryl) and its derivatives with various nucleophiles (Scheme 13) [49][50]. Thus, heating the diols 63 with an aromatic or

Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

• Vadim A. Soloshonok and
• Donna J. Nelson

Beilstein J. Org. Chem. 2011, 7, 744–758, doi:10.3762/bjoc.7.85

• ]. It is well established that the rate determining step in benzenesulfenyl chloride addition is the formation of thiiranium intermediate; specifically the alkene π electrons displace Cl− in an SN2 reaction to give the thiiranium ion [89]. On the other hand, recent studies ruled out the formation of the

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

• the preparation of certain families of tertiary thiols and thioethers. For example, SN2 displacement of a mesylate leaving group by thiophenol can be accomplished using α-hydroxy esters 2 (Scheme 1) [12]. The presence of the α-ester group of 3 promotes SN2 reaction in two ways: The electron

• cyanohydrins, can also be made to undergo SN2 reaction with sulfur nucleophiles [13]. However, substitution of the quaternary α-(sulfonyloxy)nitrile 11 is very slow, and conversion of 11 to 12 with potassium thioacetate in DMF proceeds in only 35% yield after 72 hours. SN2 displacement of the leaving group by

Oxidative cyclization of alkenols with Oxone using a miniflow reactor

• Yoichi M. A. Yamada,
• Kaoru Torii and
• Yasuhiro Uozumi

Beilstein J. Org. Chem. 2009, 5, No. 18, doi:10.3762/bjoc.5.18

• subsequent oxirane ring opening with the intramolecular oxygen nucleophile (an intramolecular SN2 reaction) to afford the product 2 stereospecifically [44][45]. It should be noted that the miniflow cyclization of 1a was continuously carried out to give a quantitative conversion of 2a over 2 h. Conclusion In

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• of PMe3 to alkene 4 generates the dipolar intermediate. The latter abstracts a proton from the α-fluoro-substituted methylene derivative 3, followed by an intermolecular SN2 reaction to furnish the desired product 5 and the release of PMe3 (Scheme 1). The mechanism supports the fact that the less