- Infrared studies of conformational isomerism in some gem-chloronitrosoalkanes
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The IR spectra of 2-chloro-2-nitrosopropane, 2-chloro-2-nitrosobutane and 2-chloro-3-methyl-2-nitrosobutane have been studied in the gas phase and solid phase, and in solutions of varying polarity.The spectra reveal clear evidence for the hindered internal rotation of the NO functional group about the C-N bond in a splitting of the N=O stretching band.The spectra can be interpreted as arising from energetically favoured cis conformational isomers, exhibiting the higher of the observed N=O stretching frequencies.In each case, assignment of the lower N=O stretching frequency is uncertain on the basis of experimental evidence.The results of semi-empirical molecular orbital calculations, however, support the assignment of this feature to the gauche conformational isomers.Temperature dependent IR spectroscopy has been employed in the determination of conformational enthalpy differences in both the gas phase and non-polar solution, which are then compared to the results of semi-empirical molecular orbital calculations.
- Evans, K. M.,Ireson, S. J.,McCoustra, M. R. S.,Pfab, J.
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- A modular, low footprint and scalable flow platform for the expedient α-aminohydroxylation of enolizable ketones
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The unique reactivity profile of α-chloronitroso derivatives is expressed to its fullest potential through the development of an integrated, modular and scalable continuous flow process for the electrophilic α-aminohydroxylation of various enolizable ketones. Flow conditions contribute to mitigating the high reactivity and toxicity of α-chloronitroso derivatives and provide an efficient, versatile and safe protocol for the α-aminohydroxylation of ketones with a minimal footprint. Fundamental aspects of the α-aminohydroxylation process were computed by DFT and further supported the experimental observations, hence leading to the unprecedented α-chloronitroso-based α-aminohydroxylation of primary, secondary and tertiary substrates. Recycling of the carbon backbone of the α-chloronitroso derivatives provides a high atom economy for the preparation of value-added molecules. This work showcases α-chloronitroso derivatives as economic and efficient vehicles for transferring electrophilic synthons of hydroxylamine toward nucleophilic enolates. A representative range of precursors and analogs of pharmaceutical active ingredients, including WHO essentials and drugs in shortage (such as epinephrine and ketamine), are prepared within minutes according to a fully concatenated process. The process features sequential modules with distinct unit operations including chemical transformations and multiple in-line extractions. The process relies on an upstream chemical Generator that manages the preparation of α-chloronitroso derivatives and that feeds downstream a series of α-aminohydroxylation modules. The setup is amenable to the addition of libraries of compounds for feeding upstream the process of discovery in medicinal chemistry and is transposable to pilot scale. Several layers of in-line analytical procedures are featured to improve process control and safety.
- Kassin, Victor-Emmanuel H.,Morodo, Romain,Toupy, Thomas,Jacquemin, Isaline,Van Hecke, Kristof,Robiette, Rapha?l,Monbaliu, Jean-Christophe M.
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supporting information
p. 2336 - 2351
(2021/04/07)
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- New and improved methods for the conversion of nitroalkanes into geminal chloronitroso compounds
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The scope and limitations of a new method for the preparation of geminal chloronitroso compounds involving treatment of a nitronate anion with oxalyl chloride are described in full, and a milder, high yielding, and more chemoselective variant using the de
- Bou-Moreno, Rafael,Luengo-Arratta, Sandra,Pons, Valerie,Motherwell, William B.
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- Observations on the reaction of nitronate anions with oxalyl chloride: A new method for the preparation of geminal chloronitroso compounds
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A simple method for the preparation of geminal chloronitroso compounds from secondary nitro compounds via their derived nitronate anions is presented.
- Bou-Moreno, Rafael,Luengo-Arratta, Sandra,Motherwell, William B.
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supporting information; experimental part
p. 2097 - 2099
(2011/05/09)
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- Nouvelles donnees sur la reaction entre le chlorure de pyridinium et les nitroalcanes. Cas du nitro-2 propane
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We have previously established that a refluxing mixture of a pyridinium halide and a primary nitroalcane gives rise to unexpected electrophilic halogenation of activated aromatic compounds with good yield (1).We confirm here that such unusual halogenation can be performed by means of pyridinium chloride and 2-nitropropane.Thus, when refluxing these two latter reagents in the presence of 2-methoxynaphtalene 1, 60percent of 1-chloro-2-methoxynaphtalene 2 is formed.However, the other products of the reaction (nitrogen oxides, 2-chloro-2-nitrosopropane 3, anetone and acetone oxime) are different from those formed with nitroethane (1-acetylpyridinium chloride oxime, acetohydroxamic acid, acetonitrile, acetamide, acetic acid and ammonium chloride).Although their results are notably different, both transformations induced respectively by the primary or the secondary nitroalcane start with the formation of a protonated nitronic acid and proceed according to similar mechanisms, as a consequence of the nucleophilic attack of the aci-nitro intermediate, among others, by the chloride anion.
- Dauzonne, Daniel,Demerseman, Pierre,Royer, Rene
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p. 204 - 206
(2007/10/02)
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