16251-46-0Relevant articles and documents
Pure by NMR ?
Claridge, Timothy D. W.,Davies, Stephen G.,Polywka, Mario E. C.,Roberts, Paul M.,Russell, Angela J.,Savory, Edward D.,Smith, Andrew D.
, p. 5433 - 5436 (2008)
(Chemical Equation Presented) Integration of a 13C-1H satellite peak of a given 12C-1H parent resonance within a quantitative 1H NMR spectrum and comparison to the minor component represents a simple protocol for the accurate determination of diastereoisomeric ratios of up to 1000:1 (i.e., 99.8% de).
Synthesis of 2-Arylethylamines by the Curtius Rearrangement
Schulze, Matthias
experimental part, p. 1461 - 1476 (2010/07/08)
2-Arylethylamine derivatives were synthesized using the Curtius reaction and with three different methods of preparing the acyl azide functional group. Carbamates derived from isocyanate were convenient protecting groups for alkylation of amines. Starting from benzaldehyde, amphetamine was prepared in three steps through an oxazolidin-2-one intermediate in 62% overall yield. Copyright Taylor & Francis Group, LLC.
Carbon dioxide as a carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas: Scope and limitations
Paz, Jairo,Perez-Balado, Carlos,Iglesias, Beatriz,Munoz, Luis
supporting information; experimental part, p. 3037 - 3046 (2010/07/15)
Carbon dioxide can be used as a convenient carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas. The transient carbamate anion generated by treating a primary or secondary amine group in basic media can be activated with phosphorylating agents such as Diphenylphosphoryl azide (DPPA) and Diphenyl chlorophosphate (DPPCl) but also with other types of electrophiles such as SOCl2, TsCl, or AcCl. The intramolecular trapping of the activated carbamate by a hydroxyl group leads to the formation of 2-oxazolidinones or 2-oxazinones in good to excellent yields. This methodology was successfully applied to the synthesis of cyclic ureas up to 7-membered rings from the corresponding diamines.
1,3-Heterazolidines-2-heterounsaturated compounds derived from ephedrines
Cruz, Alejandro,Contreras, Rosalinda,Padilla-Martinez, Itzia I.,Juarez-Juarez, Minerva
, p. 1499 - 1505 (2007/10/03)
Herein, a direct and easy method for preparing 2-oxo-, 2-thione- or 2-imine-1,3-heterazolidines derived from ephedrines and norephedrines are reported. The method is based on solvent free heating of ephedrines with oxocyanate or thiocyanate salts (180-200 °C). In the reactions with potassium oxocyanate in refluxing ethanol, it was possible to isolate ureidic derivatives. The structure and stereochemistry of the compounds were determined by 1H, 13C NMR, IR spectroscopies and mass spectrometry. Ureidic derivatives, cis-1,5-dimethyl-4-phenyl-imidazolidine-2-thione and trans-4-methyl-5-phenyl-thiazolidine-2-one are new compounds. Ephedrineurea, cis-1,5-dimethyl-4-phenyl-imidazolidine-2-thione and trans-4-methyl-5-phenyl-thiazolidine-2-one were also studied by X-ray diffraction.
Reactivity difference between diphosgene and phosgene in reaction with (2,3-anti)-3-amino-1,2-diols
Hamdach,El Hadrami,Gil,Zaragozá,Zaballos-García,Sepúlveda-Arques
, p. 6392 - 6397 (2007/10/03)
In reactions of (2,3-anti)-3-amino-1,2-diols with diphosgene and phosgene and their conversion into 1,3-oxazolidin-2-ones, some differences in the stereochemistry of the reactions have been found with these two reagents. The reactions with phosgene afforded the expected cis-oxazolidinones, and in the reaction with diphosgene under the same reaction conditions, the trans-oxazolidinones were also obtained.
The reaction of β-amino alcohols with 1,1′ -carbonyldiimidazole - Influence of the nitrogen substituent on the reaction course
Cutugno, Sara,Martelli, Gianluca,Negro, Lucia,Savoia, Diego
, p. 517 - 522 (2007/10/03)
The reaction of β-amino alcohols with 1,1′carbonyldiimidazole in dichloromethane is affected by the size of the nitrogen substituent. 1,3-Oxazolidin-2-ones are exclusively obtained from N-H, N-methyl and N-arylmethyl derivatives. O-(1-Imidazolyl)carbonyl derivatives are formed as intermediates from N-[1-(2-pyridyl)alkyl]-(S)-valinol and are mainly or exclusively converted into aziridines in the presence of water, although the cyclization is impeded by large N-substituents such as triphenylmethyl.
Photocycloaddition of N-acyl enamines to aldehydes and its application to the synthesis of diastereomerically pure 1,2-amino alcohols
Bach,Schroder
, p. 1265 - 1273 (2007/10/03)
The regio- and stereoselective synthesis of the protected cis-3- aminooxetanes cis-5 and cis-7 is reported. The oxetanes were obtained by the photocycloaddition of aliphatic (6c-e) and aromatic (4, 6a) aldehydes to the corresponding enamides (1a-d,h) or enecarbamates (1e-g). The enamine derivatives used in the Paterno-Buchi reaction were either commercially available or prepared from the corresponding acetaldehyde imines 2 by acylation. The oxetane formation proceeded with good-to-excellent simple diastereoselectivity for aromatic aldehydes (56-82% yield) and moderate selectivity for aliphatic aldehydes (46-55% yield). The cis-3-aminooxetanes are precursors for syn- and anti-1,2-amino alcohols. The relative configuration established in the photochemical step was retained upon nucleophilic ring opening between the oxygen atom and carbon atom C-4. By this means, syn-1,2-amino alcohols such as 8 and 10 were available in good yields. In contrast, the N-Boc-protected cis-3-aminooxetanes cis-5e and cis- 5f were transformed into anti-1,2-amino alcohols. Upon treatment with trifluoroacetic acid, they underwent an intramolecular nucleophilic substitution at the carbon atom C-2 of the oxetane and the oxazolidinones 11 and 12 were formed. Because the substitution occurs with inversion of configuration, anti-1,2-amino alcohols, e.g., ephedrine (15), are accessible.
Kinetic resolution of secondary alcohols using proline-derived bicyclic iminium salts
Aitken, R. Alan,Ali, Karamat,Mesher, Shaun T. E.
, p. 4179 - 4182 (2007/10/03)
The proline-derived bicyclic iminium salt 3 can be used to bring about kinetic resolution in its reaction with salts of secondary alcohols to give the corresponding methyl sulfides. Reaction proceeds most efficiently with sodium 1-phenylethoxide in toluene at RT where either 3 or the benzyl salt 14 give e.e.s of 21-25% and changing the heteroatoms present in the sails, the metal cation used and the solvent and temperature all give similar or lower selectivity.
Heterocyclizations of N-Boc derivatives of β-amino alcohols and thio analogs: an unusual case of the Thorpe-Ingold effect
Agami, Claude,Couty, Francois,Hamon, Louis,Venier, Olivier
, p. 808 - 814 (2007/10/02)
Enantiopure oxazolidin-2-ones were synthesized from chiral N-Boc β-aminoalcohols which underwent a cyclization upon treatment with tosyl chloride.This reaction was strongly accelerated in the case of carbamates derived from N-methylated amines.A similar heterocyclization was observed with dithiocarbamates, ie sulfur analogs of carbamates.The rate enhancement due to the nitrogen substitution was studied by AM1 calculations. - Keywords: carbamate; dithiocarbamate; oxazolidinone; thiazolidinone; AM1 calculations
Chiral oxazolidinones from N-Boc derivatives of β-amino alcohols. Effect of a N-methyl substituent on reactivity and stereoselectivity
Agami, Claude,Couty, Francois,Hamon, Louis,Venier, Olivier
, p. 4509 - 4512 (2007/10/02)
Treatment of N-tert-butoxycarbonyl derivatives of homochiral β-amino alcohols with p-toluenesulfonyl chloride affords 2-axazolidinones. These heterocycles were produced by intramolecular nucleophilic attack of the carbamate moiety in an intermediate tosylate. The presence of a N-methyl substituent enhanced the cyclization rate and this effect was studied by AMI calculations.
