- Ni-Catalyzed Carboxylation of Aziridines en Route to β-Amino Acids
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A Ni-catalyzed reductive carboxylation of N-substituted aziridines with CO2 at atmospheric pressure is disclosed. The protocol is characterized by its mild conditions, experimental ease, and exquisite chemo- and regioselectivity pattern, thus unlocking a new catalytic blueprint to access β-amino acids, important building blocks with considerable potential as peptidomimetics.
- Davies, Jacob,Janssen-Müller, Daniel,Zimin, Dmitry P.,Day, Craig S.,Yanagi, Tomoyuki,Elfert, Jonas,Martin, Ruben
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supporting information
p. 4949 - 4954
(2021/04/07)
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- Iron(ii)-catalyzed intermolecular aziridination of alkenes employing hydroxylamine derivatives as clean nitrene sources
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The iron-catalyzed intermolecular aziridination of alkenes with hydroxylamine derivatives is described. Using simple iron(ii) sources and readily available ligands, the formal (2 + 1) cycloaddition process proved to be efficient on both styrenes and aliphatic alkenes, providing access to a wide range of aziridines. In these particularly sustainable reaction conditions, yields up to 89% could be obtained, with a catalyst loading which could be lowered to 5 mol% when the reaction was performed on large scale. Preliminary mechanistic studies suggest that both concerted and stepwise pathways are operating in this transformation. This journal is
- Berhal, Farouk,Grimaud, Laurence,Kirby, Georgina,Prestat, Guillaume,Vitale, Maxime R.
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p. 9428 - 9432
(2021/12/09)
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- Synthesis and hetero-Diels-Alder reactions of enantiomerically pure dihydro-1: H -azepines
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Thermolysis of enantiomerically pure 3-substituted 7,7-dihalo-2-azabicyclo[4.1.0]heptanes in the presence of K2CO3 gives in good yields 2-alkyl-6-halo-1-tosyl-2,3-dihydro-1H-azepines. These undergo highly stereoselective [4+2] cycloaddition reactions with heterodienophiles and arylation/alkenylation under Suzuki conditions.
- Craig, Donald,Spreadbury, Samuel R. J.,White, Andrew J. P.
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supporting information
p. 9803 - 9806
(2020/09/16)
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- Synthesis of β-Phenethylamines via Ni/Photoredox Cross-Electrophile Coupling of Aliphatic Aziridines and Aryl Iodides
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A photoassisted Ni-catalyzed reductive cross-coupling between tosyl-protected alkyl aziridines and commercially available (hetero)aryl iodides is reported. This mild and modular method proceeds in the absence of stoichiometric heterogeneous reductants and uses an inexpensive organic photocatalyst to access medicinally valuable β-phenethylamine derivatives. Unprecedented reactivity was achieved with the activation of cyclic aziridines. Mechanistic studies suggest that the regioselectivity and reactivity observed under these conditions are a result of nucleophilic iodide ring opening of the aziridine to generate an iodoamine as the active electrophile. This strategy also enables cross-coupling with Boc-protected aziridines.
- Steiman, Talia J.,Liu, Junyi,Mengiste, Amanuella,Doyle, Abigail G.
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supporting information
p. 7598 - 7605
(2020/04/21)
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- Carbon Isotope Labeling Strategy for β-Amino Acid Derivatives via Carbonylation of Azanickellacycles
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A series of 4-membered azametallacycles have been prepared by the oxidative addition of Ni(0) with aziridines. Stoichiometric 13C-labeled carbon monoxide could be efficiently incorporated via Ni-C bond insertion to generate air stable and isola
- Ravn, Anne K.,Vilstrup, Maria B. T.,Noerby, Peter,Nielsen, Dennis U.,Daasbjerg, Kim,Skrydstrup, Troels
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supporting information
p. 11821 - 11826
(2019/08/16)
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- Cu-Catalyzed [3 + 3] Cycloaddition of Isocyanoacetates with Aziridines and Stereoselective Access to α,γ-Diamino Acids
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We report herein an efficient Cu-catalyzed formal [3 + 3] cycloaddition of isocyanoacetates with readily available aziridines of different substitution patterns, which provides a practical access to valuable 1,4,5,6-tetrahydropyrimidine derivatives. In pa
- Kok, Germaine Pui Yann,Yang, Hui,Wong, Ming Wah,Zhao, Yu
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supporting information
p. 5112 - 5115
(2018/09/12)
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- Synthesis of tubuphenylalanine and epi-tubuphenylalanine via regioselective aziridine ring opening with carbon nucleophiles followed by hydroboration-oxidation of 1,1-substituted amino alkenes
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An efficient synthesis of N-Boc-tubuphenylalanine benzyl ester (N-Boc-Tup-OBn, 1a) and N-Boc-epi-tubuphenylalanine benzyl ester (N-Boc-epi-Tup-OBn, 1b) is reported herein. Regioselective aziridine 4 ring opening with carbon nucleophiles followed by hydrob
- Reddy, Ramesh B.,Dudhe, Premansh,Chauhan, Priyanka,Sengupta, Sagnik,Chelvam, Venkatesh
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p. 6946 - 6953
(2018/10/24)
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- Synthesis of indolines: Via a palladium/norbornene-catalyzed reaction of aziridines with aryl iodides
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A Pd- and norbornene-catalyzed domino procedure has been developed to synthesize indoline compounds. This reaction provides efficient access to indolines by employing aryl iodides with aziridines as new electrophiles. The transformation is scalable and tolerates a range of functional groups.
- Liu, Ce,Liang, Yujie,Zheng, Nian,Zhang, Bo-Sheng,Feng, Yuan,Bi, Siwei,Liang, Yong-Min
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supporting information
p. 3407 - 3410
(2018/04/05)
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- Enantiodivergent Synthesis of (+)- and (?)-Pyrrolidine 197B: Synthesis of trans-2,5-Disubstituted Pyrrolidines by Intramolecular Hydroamination
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A highly efficient, diastereoselective, iron(III)-catalyzed intramolecular hydroamination/cyclization reaction involving α-substituted amino alkenes is described. Thus, enantiopure trans-2,5-disubstituted pyrrolidines and trans-5-substituted proline derivatives were synthesized by means of a combination of enantiopure starting materials, easily available from l-α-amino acids, with sustainable metal catalysts such as iron(III) salts. The scope of this methodology is highlighted in an enantiodivergent approach to the synthesis of both (+)- and (?)-pyrrolidine 197B alkaloids from l-glutamic acid. In addition, a computational study was carried out to gain insight into the complete diastereoselectivity of the transformation.
- Pérez, Sixto J.,Purino, Martín A.,Cruz, Daniel A.,López-Soria, Juan M.,Carballo, Rubén M.,Ramírez, Miguel A.,Fernández, Israel,Martín, Víctor S.,Padrón, Juan I.
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supporting information
p. 15529 - 15535
(2016/10/13)
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- Achieving regio- and stereo-control in the fluorination of aziridines under acidic conditions
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We developed an efficient fluorination protocol that converts easily accessible aziridines into β-fluoroamines, which are important motifs in biologically active molecules. In contrast with traditional fluorination approaches, DMPU-HF has shown both highe
- Okoromoba, Otome E.,Li, Zhou,Robertson, Nicole,Mashuta, Mark S.,Couto, Uenifer R.,Tormena, Cláudio F.,Xu, Bo,Hammond, Gerald B.
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supporting information
p. 13353 - 13356
(2016/11/18)
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- Highly regioselective nickel-catalyzed cross-coupling of N -tosylaziridines and alkylzinc reagents
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Herein, we report the first ligand-controlled, nickel-catalyzed cross-coupling of aliphatic N-tosylaziridines with aliphatic organozinc reagents. The reaction protocol displays complete regioselectivity for reaction at the less hindered C-N bond, and the products are furnished in good to excellent yield for a broad selection of substrates. Moreover, we have developed an air-stable nickel(II) chloride/ligand precatalyst that can be handled and stored outside a glovebox. In addition to increasing the activity of this catalyst system, this also greatly improves the practicality of this reaction, as the use of the very air-sensitive Ni(cod)2 is avoided. Finally, mechanistic investigations, including deuterium-labeling studies, show that the reaction proceeds with overall inversion of configuration at the terminal position of the aziridine by way of aziridine ring opening by Ni (inversion), transmetalation (retention), and reductive elimination (retention).
- Jensen, Kim L.,Standley, Eric A.,Jamison, Timothy F.
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supporting information
p. 11145 - 11152
(2014/08/18)
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- Regioselective Ring-Opening Nucleophilic Addition of Aziridines through Photoredox Catalyst
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A mild and efficient procedure was developed for the regioselective ring-opening nucleophilic addition reactions of aziridines via visible light photoredox catalysis, that provides a practical synthetic access to 1,2-bifunctional compounds. Furthermore, the regioselective synthesis of non-racemic amino ethers from chiral aziridine could also be achieved under mild conditions. Finally, a possible reaction mechanism was proposed and further supported by control experiments.
- Sun, Hongnan,Yang, Chao,Lin, Run,Xia, Wujiong
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supporting information
p. 2775 - 2780
(2016/02/18)
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- An efficient synthetic approach for N-C bond formation from (S)-amino acids: An easy access to cis-2,5-disubstituted chiral piperazines
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An efficient synthetic strategy is described for the construction of amino acids derived enantiomerically pure cis-2,5-disubstituted chiral piperazines. Cu-catalyzed spontaneous regioselective ring opening and ring closing of non-activated N-tosyl aziridines as well as Pd-mediated N-C bond formation from N-tosyl halogenated amino-derivatives are the key steps for accessing disubstituted piperazines.
- Manna, Sudipta Kumar,Panda, Gautam
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p. 18332 - 18338
(2013/10/21)
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- Synthesis of 1,4-benzoxazepine derivatives via a novel domino aziridine ring-opening and isocyanide-insertion reaction
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A novel and efficient domino process has been developed for the synthesis of 1,4-benzoxazepine derivatives from a range of readily accessible N-tosylaziridines, 2-iodophenols and isocyanides. This process involves the aziridine ring-opening reaction with 2-iodophenol, followed by a palladium-catalyzed isocyanide-insertion reaction. This regioselective and high-yielding transformation could be extended to its application for the synthesis of natural products and biologically interesting heterocycles. Copyright
- Ji, Fei,Lv, Mei-Fang,Yi, Wen-Bin,Cai, Chun
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p. 3401 - 3406
(2013/12/04)
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- Stereodefined N,O-acetals: Pd-catalyzed synthesis from homopropargylic amines and utility in the flexible synthesis of 2,6-substituted piperidines
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We developed a conceptually new synthetic strategy which exploits the stereochemical information of labile acyclic N,O-acetals. The key to this strategy, chemo- and stereoselective synthesis of N,O-acetals, was achieved by the Pd-catalyzed addition of sulfonyl-protected homopropargylic amines to alkoxyallene. The N,O-acetals generated in this way were combined with Au-catalyzed cycloisomerization to give an access to 2,6-disubstituted piperidines with stereochemical flexibility.
- Kim, Haejin,Rhee, Young Ho
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supporting information; scheme or table
p. 4011 - 4014
(2012/04/10)
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- Aziridination of Olefins
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A process for aziridination of olefins using NaIO4/alkali metal bromide/H+/Chloramine-T combination in presence of dipolar aprotic solvent under ambient conditions to obtain aziridines is disclosed.
- -
-
Page/Page column 3; 5
(2012/09/05)
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- Iron(iii) tetrakis(pentafluorophenyl)porpholactone catalyzes nitrogen atom transfer to CC and C-H bonds with organic azides
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We have demonstrated that iron porpholactones could be effective catalysts for nitrogen atom transfer reactions such as aziridination of alkenes and amidation of alkanes using organic azides.
- Liang, Lei,Lv, Hongbin,Yu, Yi,Wang, Peng,Zhang, Jun-Long
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supporting information; experimental part
p. 1457 - 1460
(2012/03/22)
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- One-pot and microwave-assisted synthesis of N-sulfonylaziridines
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A novel and efficient microwave-assisted one-step reaction was developed to synthesize chiral N-sulfonylaziridines by the reaction of different chiral amino alcohols and sulfonic chlorides. The newly developed microwave synthetic method has the advantage of reducing the reaction time from 24 to 0.5 h with improved yields (84-93%) and minimizing by-products.
- Xu, Hao,Tian, Hua,Zheng, Liangyu,Liu, Qingwen,Wang, Li,Zhang, Suoqin
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experimental part
p. 2873 - 2875
(2011/06/21)
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- Regioselective ring-opening of amino acid-derived chiral aziridines: An easy access to cis-2,5-disubstituted chiral piperazines
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An efficient four-step synthetic strategy for cis-2,5-disubstituted chiral piperazines derived from amino-acid-based aziridines is described. The key steps in this strategy are the highly regioselective boron trifluoride diethyl etherate (BF3·OEt2)-mediated ring-opening of less-reactive N-Ts chiral aziridines by α-amino acid methyl ester hydrochloride followed by Mitsunobu cyclization. This protocol has been used in an attempt to construct the piperazine core framework of natural product (+)-piperazinomycin. The pied piperazines: A four-step efficient synthetic strategy for cis-2,5-disubstituted chiral piperazines derived from amino acid-based aziridines is described. The key reaction steps are the highly regioselective BF3·OEt2 mediated ring-opening of less-reactive N-Ts chiral aziridines by α-amino acid methyl ester hydrochlorides, followed by a Mitsunobu cyclization. This protocol has been used in an attempt to construct the piperazine core framework of natural product (+)-piperazinomycin. Copyright
- Samanta, Krishnananda,Panda, Gautam
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supporting information; experimental part
p. 189 - 197
(2011/10/08)
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- Facile synthesis of oxazolidinones catalyzed by n-Bu4NBr 3/n-Bu4NBr directly from olefins, chloramine-T and carbon dioxide
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A binary catalyst systemcomposed of n-Bu4NBr3/n-Bu4NBrwas developed for facile synthesis of 5-substituted 2-oxazolidinoneswith perfect regioselectivity in a single operation directly fromolefins, chloramine-T and CO2. The choice of efficient binary catalysts for two steps, i.e. aziridination and cycloaddition, and the optimization of reaction condition are keys to the one-pot synthesis of 5-substituted 2-oxazolidinones. A possiblemechanismfor the present one-pot synthesis of oxazolidinones was also proposed.
- Kong, De-Lin,He, Liang-Nian,Wang, Jin-Quan
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experimental part
p. 992 - 995
(2010/11/16)
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- NaIO4/LiBr-mediated aziridination of olefins using chloramine-T
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A new milder protocol for aziridination of a variety of olefins has been described. The process employs catalytic amount of sodium metaperiodate (NaIO4) as an oxidant and LiBr and chloramine-T as the bromine and nitrogen sources, respectively. Interestingly, the formation of aziridine products in all the cases studied takes place presumably through a process of 1,2-aminobromination of alkenes.
- Karabal, Pratibha U.,Chouthaiwale, Pandurang V.,Shaikh, Tanveer M.,Suryavanshi, Gurunath,Sudalai, Arumugam
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experimental part
p. 6460 - 6462
(2011/01/03)
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- [FeIII(F20-tpp)Cl] Is an effective catalyst for nitrene transfer reactions and animation of saturated hydrocarbons with sulfonyl and aryl azides as nitrogen source under thermal and microwave-assisted conditions
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[FeIII(F20-tpp)Cl] (F20tpp = meso- tetrakis(pentafluorophenyl)porphyrinato dianion) is an effective catalyst for imido/nitrene insertion reactions using sulfonyl and aryl azides as nitrogen source. Under thermal conditions, aziridination of aryl and alkyl alkenes (16 examples, 60-95% yields), sulfimidation of sulfides (11 examples, 76-96% yields), allylic amidation/amination of α-methylstyrenes (15 examples, 68-83% yields), and amination of saturated C-H bonds including that of cycloalkanes and adamantane (eight examples, 64-80% yields) can be accomplished by using 2 mol % [FeIII(F20- tpp)Cl] as catalyst. Under microwave irradiation conditions, the reaction time of aziridination (four examples), allylic amination (five examples), sulfimidation (two examples), and amination of saturated C-H bonds (three examples) can be reduced by up to 16fold (24-48 versus 1.5-6 h) without significantly affecting the product yield and substrate conversion.
- Liu, Yungen,Che, Chi-Ming
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experimental part
p. 10494 - 10501
(2010/10/21)
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- Catalyst-free aziridination and unexpected homologation of aziridines from imines
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Aziridination and unpredicted homologation reaction of N-sulfonylimines were achieved easily with a very simple, rapid and mild procedure through the use of diazomethane without the presence of any catalyst. The method represents an attractive alternative
- Branco, Paula Serio,Raje, Vivek Prabhakar,Dourado, Jorge,Gordo, Joana
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experimental part
p. 2968 - 2974
(2010/09/06)
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- Addition reactions of chloro- Or iodomethyllithium to imines. Synthesis of enantiopure aziridines and β-chloroamines
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We report a novel, simple, and efficient synthesis of aziridines and l-chloroalkan-2-amines by the reaction of imines derived from various aldehydes and p-toluenesulfonamide or benzenesulfonamide with iodoor chloromethyllithium, respectively. Both halogenated anions were generated in situ by treatment of diiodo- or chloroiodomethane with methyllithium at -78 or 0 °C. The reaction of in situ generated iodoor chloromethyllithium could also be performed from chiral 2-aminoaldimines to yield enantiopure aziridines or (2S,3S)-2,3-diamino- l-chloroalkanes with high stereoselectivity.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Bernad, Pablo L.,Simal, Carmen
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supporting information; experimental part
p. 2452 - 2459
(2009/07/18)
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- Synthesis and biological evaluation of reversible inhibitors of IdeS, a bacterial cysteine protease and virulence determinant
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Analogues of the irreversible protease inhibitors TPCK and TLCK have been synthesized and tested as inhibitors of the bacterial cysteine protease IdeS excreted by Streptococcus pyogenes. Eight compounds were identified as inhibitors of IdeS in an in vitro
- Berggren, Kristina,Johansson, Bjoern,Fex, Tomas,Kihlberg, Jan,Bjoerck, Lars,Luthman, Kristina
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scheme or table
p. 3463 - 3470
(2009/09/25)
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- Enantioselective syntheses of morpholines and their homologues via S N2-type ring opening of aziridines and azetidines with haloalcohols
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(Chemical Equation Presented) A highly regio- and stereoselective strategy for the syntheses in high yield and enantioselectivity of a variety of substituted nonracemic morpholines and their homologues is described. The reaction proceeds via an SN2-type ring opening of activated aziridines and azetidines by suitable halogenated alcohols in the presence of Lewis acid followed by base-mediated intramolecular ring closure of the resulting haloalkoxy amine.
- Ghorai, Manas K.,Shukla, Dipti,Das, Kalpataru
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body text
p. 7013 - 7022
(2009/12/22)
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- Alkali metals in silica gel (M-SG): A new reagent for desulfonation of amines
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(Chemical Equation Presented) A novel method for the desulfonation of secondary amines is described. Alkali metals absorbed into nanostructured silica (M-SG) were found to be useful solid-state reagents for the desuffonation of a range of N,N-disubstituted sulfonamides. M-SG reagents are room-temperature- stable free-flowing powders that retain the chemical reactivity of the parent metal, decreasing the danger and associated cost of using reactive metals.
- Nandi, Partha,Redko, Mikhail Y.,Petersen, Kathryn,Dye, James L.,Lefenfeld, Michael,Vogt, Paul F.,Jackson, James E.
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supporting information; experimental part
p. 5441 - 5444
(2009/06/18)
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- Addition reactions of iodomethyllithium to imines. A direct and efficient synthesis of aziridines and enantiopure amino aziridines
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(Chemical Equation Presented) An efficient and general synthesis of aziridines by the reaction of imines derived from p-toluenesulfonamides with in situ generated iodomethyllithium, with a simple and rapid experimental protocol, is reported for the first time. The reaction with the chiral aldimine derived from phenylalaninal allowed access to (2R,1′S)-2-(1′-aminoalkyl) aziridine with very high diastereoselectivity, in enantiopure form. A mechanism to explain this novel reaction is proposed.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Simal, Carmen
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supporting information; experimental part
p. 4457 - 4460
(2009/05/07)
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- Two-step synthesis of N-sulfonyl aziridines from epoxides
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A convenient and high-yielding two-step synthesis of N-sulfonyl aziridines starting from epoxides is described. The method, which involves epoxide ring opening with sulfonamides and subsequent mesylation-cyclisation, is particularly suitable for variation
- Huang, Jianhui,O'Brien, Peter
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p. 425 - 434
(2007/10/03)
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- Chiral bicyclic guanidines: A concise and efficient aziridine-based synthesis
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A series of chiral bicyclic guanidines, either symmetrical or non-symmetrical, was synthesized using a concise and efficient aziridine-based synthetic methodology. Starting from commercial amino alcohols, five synthetic steps were performed, with only thr
- Ye, Weiping,Leow, Dasheng,Goh, Serena Li Min,Tan, Chin-Tong,Chian, Chee-Hoe,Tan, Choon-Hong
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p. 1007 - 1010
(2007/10/03)
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- Ring opening and expansion of aziridines in a silica-water reaction medium
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Ring-opening reactions of N-tosylaziridines with water-soluble nucleophiles proceeded in a silica-water reaction medium. The system is applicable to a ring expansion of an aziridine with potassium thiocyanate, leading to a thiazolidine derivative.
- Minakata, Satoshi,Hotta, Takahiro,Oderaotoshi, Yoji,Komatsu, Mitsuo
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p. 7471 - 7472
(2007/10/03)
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- Two-step syntheses of 2,4,6-triisopropylbenzenesulfonyl aziridines
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In a continuing study on the α-lithiation of N-tosyl aziridines, it is reported that ortho-lithiation of the N-tosyl group is occurring under typical α-lithiation conditions (s-BuLi/PMDETA). Thus, a simple, two-step synthesis of N-2,4,6-triisopropylbenzen
- Huang, Jianhui,O'Brien, Peter
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p. 3253 - 3256
(2007/10/03)
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- Lewis base catalyzed ring opening of aziridines with silylated nucleophiles
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(Chemical Equation Presented) The ring opening of N-tosylaziridines with trimethylsilylated nucleophiles, catalyzed by N,N,N′,N′- tetramethylethylenediamine, led to the production of β-functionalized sulfonamides in good to excellent yields with high regi
- Minakata, Satoshi,Okada, Yuriko,Oderaotoshi, Yoji,Komatsu, Mitsuo
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p. 3509 - 3512
(2007/10/03)
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- Large scale synthesis of optically pure aziridines
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Disclosed is an efficient, inexpensive method for the preparation of chiral aziridines on a large scale.
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- Short and efficient synthesis of optically active N-tosyl aziridines from 2-amino alcohols
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Two alternative and complementary one-pot procedures for the direct transformation of 2-amino alcohols to N-tosyl aziridines are presented. The unsubstituted parent compound and its less hindered homologues can be obtained in high yields by tosylation and
- Bieber, Lothar W.,De Araujo, Maria C. F.
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p. 902 - 906
(2007/10/03)
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- A new convenient approach to chiral β-aryl(heteroaryl)alkylamines
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Chiral β-aryl(heteroaryl)alkylamines have been prepared from N-tosyl alkylaziridines via regiospecific nucleophilic ring opening and subsequent desulfonylation in good to excellent yields. The corresponding aziridines are easily obtained from commercially available (S)-α-amino acids, so this method is the first effective route to asymmetric β-aryl(heteroaryl)alkylamines.
- Nenajdenko, Valentine G,Karpov, Alexei S,Balenkova, Elizabeth S
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p. 2517 - 2527
(2007/10/03)
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- Amidation of saturated C-H bonds catalyzed by electron-deficient ruthenium and manganese porphyrins. A highly catalytic nitrogen atom transfer process
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(equation presented) Amidation of a variety of hydrocarbons with PhI=NTs catalyzed by ruthenium and manganese meso-tetrakis(pentafluorophenyl)porphyrins 1 and 2 afforded N-substituted amides in up to 92% yields with good to excellent substrate conversions. By employing catalyst 2, exceptionally high turnovers (up to 2600) were achieved, and the amidations can be effected by directly using PhI(OAc)2/NH2R as amidating reagents; in the case of R = COCF3 a direct amination was realized in up to 90% yield.
- Yu, Xiao-Qi,Huang, Jie-Sheng,Zhou, Xiang-Ge,Che, Chi-Ming
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p. 2233 - 2236
(2007/10/03)
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- Preparation and ring-opening reactions of N-diphenylphosphinyl aziridines
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Monochiral N-Diphenyphosphinyl aziridines ('N-Dpp azinidines') may efficiently be prepared from monochiral 2-aminoalcohols. Such aziridines undergo ring-opening reaction with a variety of nucleophiles in good yield. Dephosphinylation is accomplished under mild conditions.
- Cantrill, Alex A.,Osborn, Helen M. I.,Sweeney, Joseph
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p. 2181 - 2208
(2007/10/03)
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- Deprotection of sulfonyl aziridines
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The deprotection of the chiral N-sulfonyl aziridines 1-3 has been studied under different desulfonylation conditions. Two methods for the efficient aleprotection of 2-benzyl-, 2-phenyl-, and 2-carboxyl-N- sulfonylaziridines were found. The desulfonylation with lithium and a catalytic amount of di-tert-butyl biphenyl in THF at -78 °C led to the corresponding NH aziridines with yields up to 85%. Alternatively, the desulfonylation could be carried out with magnesium in methanol under ultrasonic conditions. The latter proved to be a very mild method and afforded the desulfonylated aziridines with yields up to 75%, even when the 2-phenyl substituted aziridine 2 was the studied substrate. Furthermore, in all the cases studied, no racemization was observed in the chiral center of the aziridines.
- Alonso, Diego A.,Andersson, Pher G.
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p. 9455 - 9461
(2007/10/03)
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- Pyrrolidines from olefins via radical cyclization
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2,4-Disubstituted N-tosylpyrrolidines were prepared from olifeins via N- tosylaziridination, benseneselenolate ring-opening and reductive radical cyclization. Azidoselenation of olefins, followed by reduction, N-tosylation, N-allylation and reductive radical cyclization, afforded 3,4-disubstituted N- tosylpyrrolidines.
- Gupta, Vijay,Besev, Magnus,Engman, Lars
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p. 2429 - 2432
(2007/10/03)
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- Preparation and evaluation of nitrene precursors (PhI=NSO2Ar) for the copper-catalyzed aziridination of olefins
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The preparation of different [N-(arenesulfonyl)imino]phenyliodinanes is described along with an evaluation of their utility as nitrene precursors for the copper-catalyzed aziridination of different olefins. The best results were obtained with p-NO2/
- Soedergren, Mikael J.,Alonso, Diego A.,Bedekar, Ashutosh V.,Andersson, Pher G.
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p. 6897 - 6900
(2007/10/03)
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- Electrogenerated Superoxide-Activated Carbon Dioxide. A New Mild and Safe Approach to Organic Carbamates
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The electrochemical reduction of O2 (E = -1.0 V vs SCE) in dipolar aprotic solvents in the presence of CO2 gave a carboxylating reagent (O2·-/CO2) able to convert amines and different types of their derivatives into carbamates. Primary and secondary aliphatic and aromatic amines were converted into the corresponding ethyl carbamates by the addition of EtI to the carbamate anions generated in the first step of the reactions. The yields were dependent on the nucleophilicity of the nitrogen atom ω-Bromoethyl- and propylamine gave 2-oxazolidinone and tetrahydro-l,3-oxazm-2-one in moderate yields. N-Acyl or N-(alkoxycarbonyl)alkylamines bearing a leaving group at the β position of the alkyl substituent were converted into 3-substituted-2-oxazolidinones in high yields. By using chiral substrates, enantiopure 3-alkoxycarbonyl(or acyl)-4-substituted oxazolidin-2-ones (70-85% isolated yields) were obtained. This represents a new mild and safe route to these important auxiliaries for asymmetric synthesis. Some limitations of the process are also evidenced and accounted for.
- Casadei, Maria Antonietta,Moracci, Franco Micheletti,Zappia, Giovanni,Inesi, Achille,Rossi, Leucio
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p. 6754 - 6759
(2007/10/03)
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- Dianions of glyoxylic acid thioketals: convenient α-keto acid equivalents
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By varying the solvent, reaction temperature, and bases (i.e., gegenions present), optimum conditions for the alkylation of the dianions of glyoxylic acid derivatives 8 and 9 were established.It was found, that the easily prepared, thermally stable, tetrahydrofuran-soluble potassium dianion of bis(ethylthio)acetic acid was readily alkylated by alkyl halides, tosylates, epoxides, and N-tosyl aziridines.The latter alkylation is being used to develop a possible cytochalasin synthesis.The alkylated products may be readily converted into the corresponding α-keto acids or methyl 2,2-bismethoxycarboxylates.
- Bates, Gordon S.,Ramaswamy, S.
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p. 716 - 722
(2007/10/02)
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