- An improved, convenient procedure for reduction of amino acids to aminoalcohols: Use of NaBH4-H2so4
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The use of NaBH4-H2SO4, For the reduction of α-amino acids to the corresponding aminoalcohols offers definite advantages: i) operational simplicity, ii) ease of scaling up the reaction without risking explosion, and iii) use of the inexpensive reagents.
- Abiko, Atsushi,Masamune, Satoru
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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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- 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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p. 9803 - 9806
(2020/09/16)
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- Synthesis of Enantiopure PZM21: A Biased Agonist of the Mu-Opioid Receptor
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PZM21 (1) was recently reported as a biased agonist of the mu-opioid receptor (MOR) with improved antinociceptive effects and reduced side effects compared with traditional opioid-based analgesics. The original synthesis of PZM21 with the desired (S,S) configuration required the separation of a diastereomeric mixture in the final step by using chiral HPLC. A concise synthesis of 1 has now been developed in the enantiomeric pure form starting with commercially available l-alanine and proceeding via a chiral aziridine as a key intermediate. The final product was obtained as the (S,S) diastereomer in seven steps in 22.5 % yield from l-alanine. This synthetic strategy could be readily applied to the development of PZM21 analogues at the thiophenyl position.
- Perrey, David,Zhang, Dehui,Nguyen, Thuy,Carroll, F. Ivy,Ko, Mei-Chuan,Zhang, Yanan
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p. 4006 - 4012
(2018/07/30)
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- Lewis acid mediated intramolecular C-O bond formation of alkanol-epoxide leading to substituted morpholine and 1,4-oxazepane derivatives: Total synthesis of (±)-Viloxazine
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Substituted morpholines have been efficiently synthesised in good yields from nitrogen tethered alkanol-epoxide mediated by boron trifluoride etherate. The methodology has been used for the total synthesis of (±)-viloxazine.
- Ghosh, Priya,Deka, Manash J.,Saikia, Anil K.
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p. 690 - 698
(2016/01/15)
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- Stereoselective geminal difunctionalization of vinyl arenes mediated by the bromonium ion
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An anti-Markovnikov geminal oxyamination of styrenyl alkenes in an intermolecular fashion using the umpolung strategy mediated by the bromonium ion is reported. Isotope labeling studies confirm the migration of the phenyl group in the semipinacol rearrang
- Balaji, Pandur Venkatesan,Chandrasekaran, Srinivasan
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supporting information
p. 70 - 72
(2014/01/06)
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- Stereoselective synthesis of morpholines via copper-promoted oxyamination of alkenes
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A new copper(II) 2-ethylhexanoate-promoted addition of an alcohol and an amine across an alkene (oxyamination) is reported. The alcohol addition is intramolecular, while coupling with the amine occurs intermolecularly. Several 2-aminomethyl morpholines we
- Sequeira, Fatima C.,Chemler, Sherry R.
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p. 4482 - 4485
(2012/10/29)
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- Palladium-catalyzed atom transfer radical cyclization of unactivated alkyl iodide
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A palladium-catalyzed atom transfer cyclization of unactivated alkyl iodide has been developed. A radical chain mechanism has been proposed for this transformation, which might not involve an alkylpalladium intermediate.
- Liu, Hui,Qiao, Zongjun,Jiang, Xuefeng
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supporting information; experimental part
p. 7274 - 7277
(2012/09/25)
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- Diversity-oriented synthesis based on the dppp-catalyzed mixed double-michael reactions of electron-deficient acetylenes and β-amino alcohols
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In this study, we prepared oxizolidines through 1,3-bis(diphenylphosphino)- propane (DPPP)-catalyzed mixed double-Michael reactions of β-amino alcohols with electron-deficient acetylenes. These reactions are very suitable for the diversity-oriented parallel syntheses of oxizolidines because: (i) they are performed under mild metal-free conditions and (ii) the products are isolated without complicated work-up. To demonstrate the applicability of mixed double-Michael reactions for the preparation of five-membered-ring heterocycles, we prepared 60 distinct oxazolidines from five β-amino alcohols and 12 electron-deficient acetylenes. We synthesized 36 of these 60 oxazolidines in enantiomerically pure form from proteinogenic amino acid-derived β-amino alcohols.
- Fan, Yi Chiao,Kwon, Ohyun
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p. 3802 - 3825
(2011/06/24)
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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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- Gold-catalyzed direct activation of allylic alcohols in the stereoselective synthesis of functionalized 2-vinyl-morpholines
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Alcohol versus alcohol: A highly stereocontrolled synthesis of substituted morpholines is realized by means of gold-catalyzed dehydrative allylic cyclization of diols (see scheme for one example; segphos = 5,5′-bis[di(3, 5-di-tert-butyl-4-methyoxyphenyl)phosphine]-4,4′-bi-1,3-benzodioxole). The present methodology represents one of the few examples of enantioselective gold-catalyzed transformations involving unactivated alkenes. Copyright
- Bandini, Marco,Monari, Magda,Romaniello, Alessandro,Tragni, Michele
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supporting information; body text
p. 14272 - 14277
(2011/03/19)
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- Synthesis of novel N-protected β3-amino nitriles: study of their hydrolysis involving a nitrilase-catalyzed step
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Several commercially available nitrilases were investigated with regard to their potential to hydrolyze N-protected β3-amino nitriles into their corresponding N-protected β3-amino acids. The biotransformations were obtained in different proportions depending on the nitrilase involved. The best hydrolysis results were achieved for the N-Cbz-β3-amino nitrile from l-alanine using the NIT-107, in a phosphate buffer at 0.05 M. However, no biotransformation into the corresponding acids was observed for the N-sulfonylamide β3-amino nitriles. Two simple and efficient procedures to prepare the β3-amino nitriles from their analogous α-amino acids are described. Thirty four new substances were synthesized and characterized over the course of this work.
- Veitia, Maite Sylla-Iyarreta,Brun, Pierre Louis,Jorda, Pierre,Falguieres, Annie,Ferroud, Clotilde
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scheme or table
p. 2077 - 2089
(2010/03/04)
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- Asymmetric Strecker reaction of N-benzhydrylimines utilising new tropos biphenyldiol-based ligands
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The synthesis of a library of N-arenesulfonyl-1,3-oxazolidinyl-substituted biphenyldiols is presented. A set of two central intermediates together with easily accessible N-arenesulfonylamino alcohols furnish a broad variety of 1,3-oxazolidines. These are applied as chiral tropos ligands in a titanium-mediated Strecker-type reaction of N-benzhydrylimines. A correlation between the ee values in the product and the diastereomeric ratio concerning the chiral axis of the ligand is made. Those substituents in the ligand which proved to lead to a higher preference for one diastereomeric conformer of the chiral axis in related compounds now provide the most selective ligands. Two privileged ligands are identified that afford superior results in 8 of 13 screenings. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Wuennemann, Stefan,Froehlich, Roland,Hoppe, Dieter
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p. 684 - 692
(2008/09/17)
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- A convenient synthetic route to enantiopure N-tosylazetidines from α-amino acids
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A general and convenient synthetic route to various chiral 2-substituted- and 2,4-disubstituted-N-tosylazetidines (ee >99%) is described in good overall yields starting from chiral α-amino acids using very simple chemistry.
- Ghorai, Manas K.,Das, Kalpataru,Kumar, Amit
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p. 2471 - 2475
(2007/10/03)
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- Synthesis of 2,4-disubstituted piperidines via radical cyclization: Unexpected enhancement in diastereoselectivity with tris(trimethylsilyl)silane
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A novel approach to 2,4-disubstituted piperidines is reported, involving the radical cyclization of 7-substituted-6-aza-8-bromooct-2-enoates. Cyclization with tributyltin hydride affords the trans piperidines with trans/cis diastereomeric ratios ranging typically from 3:1 to 6:1. Cyclization with tris(trimethylsilyl)silane affords the same products with diastereomeric ratios of up to 99:1 in certain cases. The enhancement in diastereoselectivity results from the selective rearrangement of the minor stereoisomer through a cascade process involving radical cyclization to the piperidine radical, 1,5-radical translocation, and attack of the translocated radical onto the sulfonamide with extrusion of SO2 in a Smiles-type rearrangement. Slower trapping of the piperidine radical by tris(trimethylsilyl)silane compared to tributyltin hydride accounts for the occurrence of the rearrangement cascade in the former case.
- Gandon, Lucile A.,Russell, Alexander G.,Gueveli, Tatyana,Brodwolf, Angela E.,Kariuki, Benson M.,Spencer, Neil,Snaith, John S.
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p. 5198 - 5207
(2007/10/03)
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- Stereoselective γ-lactam synthesis via palladium-catalysed intramolecular allylation
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A novel route to the synthesis of 3-(tolylsulfonyl)-4,5-cis-disubstituted γ-lactams using a diastereoselective palladium-catalysed intramolecular allylation of amino acid-derived allylic carbonates has been developed. The Royal Society of Chemistry 2005.
- Craig, Donald,Hyland, Christopher J. T.,Ward, Simon E.
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p. 3439 - 3441
(2007/10/03)
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- Asymmetric hetero-Diels-Alder reactions of N-sulfinyl dienophiles using chiral bis(oxazoline)-copper(II) and -zinc(II) triflates
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Asymmetric hetero-Diels-Alder (HDA) reactions of N-sulfinyl dienophiles using bis(oxazoline)-copper(II) and -zinc(II) triflates are described. The cycloadditions with cyclic and acyclic 1,3-dienes have been studied. In most cases, good enantioselectivitie
- Bayer, Annette,Endeshaw, Molla Mellese,Gautun, Odd R.
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p. 7198 - 7205
(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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- Selective reductions of oxazolidinones: New protocol for diastereoselective synthesis of vicinal amino alcohols
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Selective reductions of oxazolidinones using sodium borohydride and their application to the diastereoselective synthesis of vicinal amino alcohols are described.
- Reddy, G. Vidyasagar,Rao, G. Venkat,Iyengar
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p. 2653 - 2656
(2007/10/03)
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- Effective and mild method for preparation of optically active α-amino aldehydes via TEMPO oxidation
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The TEMPO oxidation method is successfully applied to preparation of variously protected, optically active α-amino aldehydes without racemization and in very good yield.
- Jurczak, Janusz,Gryko, Dorota,Kobrzycka, Elzbieta,Gruza, Henryk,Prokopowicz, Piotr
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p. 6051 - 6064
(2007/10/03)
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- New isoxazolidine-based chiral auxiliaries for asymmetric syntheses
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New chiral auxiliaries based on the bicyclic-isoxazolidine skeleton, 3-oxa-2,7-diazabicylo[3,3,0]octane derivatives, were synthesized in 60-80% overall yields from amino acids. Asymmetric alkylation and boron aldol reaction using the auxiliaries proceeded with high selectivities. 'Carboxylic amide' has been used for the asymmetric boron-mediated aldol reaction for the first time.
- Abiko, Atsushi,Liu, Ji-Feng,Wang, Guo-Qiang,Masamune, Satoru
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p. 3261 - 3264
(2007/10/03)
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