4170-24-5Relevant academic research and scientific papers
A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α-Halocarboxylic Acids
Monticelli, Serena,Urban, Ernst,Langer, Thierry,Holzer, Wolfgang,Pace, Vittorio
supporting information, p. 1001 - 1006 (2019/01/30)
The homologation of carbon dioxide with stable, (enantiopure) magnesium carbenoids constitutes a valuable method for preparing α-halo acid derivatives. The tactic features a high level of chemocontrol, thus enabling the synthesis of variously functionalized analogues. The flexibility to generate magnesium carbenoids through sulfoxide-, halogen- or proton- Mg exchange accounts for the wide scope of the reaction. (Figure presented.).
Preparation method for 2-chloro-butyric acid
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Paragraph 0016-0023, (2019/02/04)
The invention discloses a preparation method for 2-chloro-butyric acid. The preparation method comprises the following steps: taking butyric acid as raw material, chlorine as chlorinating agent, acylating chlorination reagent as catalyst and quinone compound as radical scavenger, and then reacting, thereby acquiring a target product 2-chloro-butyric acid. The preparation method has the advantagesof simple process, high selectivity, high production safety and low cost.
Reaction of Lithium Acylate α-Carbanions with Carbon Tetrachloride
Zorin,Zaynashev,Zorin
, p. 42 - 46 (2019/04/27)
Metalation of acetic, butanoic, or 2-methylpropanoic acid with lithium diisopropylamide in tetrahydrofuran under argon gave the corresponding lithium acylate α-carbanions which reacted with carbon tetrachloride at 20–25°C for 2 h to afford butanedioic acid or its 2,3-diethyl and 2,2,3,3-tetramethyl derivatives, as well as the corresponding α-chlorocarboxylic acids and chloroform. A radical mechanism was proposed for the formation of dicarboxylic and α-chlorocarboxylic acids.
High-quality S - 2 - butylene-chlorohydrin preparation method
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Paragraph 0015, (2017/08/25)
The invention relates to a preparation method of high-quality S-2-chlorobutanol. The method comprises the following steps: with L-2-aminobutyric acid prepared by a biological reduction transformation method as a raw material, preparing the S-2-chlorobutanol by adopting a diazotization chlorination method; further esterifying, and reducing with sodium borohydride/titanium tetrachloride, so as to obtain the product. According to the prepared high rotary S-2-chlorobutanol, the EE value is over 99%; and the S-2-chlorobutanol is good in repeatability and stable in process.
Reactions of α-carbanions of lithium acylates with N,N-diethyl-N-chloro- and N,N-diethyl-N-bromoamines
Zorin,Zainashev,Zorin
, p. 2469 - 2472 (2016/12/24)
The interaction of α-carbanions of lithium acylates (prepared via metalation of acetic, butyric, or isobutyric acid with lithium diisopropylamide in tetrahydrofuran under argon atmosphere) with N,N-diethyl-N-chloro- or N,N-diethyl-N-bromoamine has resulte
Forming Stereogenic Centers in Acyclic Systems from Alkynes
Vabre, Roxane,Island, Biana,Diehl, Claudia J.,Schreiner, Peter R.,Marek, Ilan
supporting information, p. 9996 - 9999 (2015/08/19)
The combined carbometalation/zinc homologation followed by reactions with α-heterosubstituted aldehydes and imines proceed through a chair-like transition structure with the substituent of the incoming aldehyde residue preferentially occupying a pseudo-axial position to avoid the two gauche interactions. The heteroatom in the axial position produces a chelated intermediate (and not a Cornforth-Evans transition structure for α-chloro aldehydes and imines) leading to a face differentiation in the allylation reaction. This method provides access to functionalized products in which three new carbon-carbon bonds and two to three stereogenic centers, including a quaternary one, were created in acyclic systems in a single-pot operation from simple alkynes. All-carbon quaternary stereocenter: The combined carbometalation/zinc homologation of alkynes followed by reactions with α-heterosubstituted aldehydes and imines provides access to functionalized acyclic adducts. These adducts obtained in a single-pot reaction have three new carbon-carbon bonds and two to three stereogenic centers, including a quaternary carbon stereocenter.
Enoate reductase-mediated preparation of methyl (S)-2-bromobutanoate, a useful key intermediate for the synthesis of chiral active pharmaceutical ingredients
Brenna, Elisabetta,Gatti, Francesco G.,Manfredi, Alessia,Monti, Daniela,Parmeggiani, Fabio
experimental part, p. 262 - 268 (2012/06/18)
Enoate reductases belonging to the Old Yellow Enzyme (OYE) family were employed to develop a biocatalysed approach to methyl (S)-2-bromobutanoate, a key intermediate for the introduction of a particular stereogenic unit into the molecular skeleton of a certain class of chiral drugs. Methyl (Z)-2-bromocrotonate afforded, respectively, (S)-2-bromobutanoic acid (ee = 97%) and methyl (S)-2-bromobutanoate (ee = 97%) by baker's yeast fermentation and by OYE1-3 biotransformations. The bioreductions of other methyl 2-haloalkenoates were also considered. It was observed that the (Z)- and (E)-diastereoisomers of α-bromo unsaturated esters afforded the same enantiomer of the corresponding reduced product.
Amber-woody scent: Alcohols with divergent structure present common olfactory characteristics and sharp enantiomer differentiation
Margot, Christian,Simmons, Dana P.,Reichlin, Daniel,Skuy, David
, p. 2662 - 2684 (2007/10/03)
Only one out of the four possible trans isomers of the important perfumery alcohol Norlimbanol (1) possesses a very strong amber-woody smell, the isomer 1A with (1′ R,3S,6'S) absolute configuration. Its enantiomer 1B is almost odorless and devoid of amber-woody character, whereas the diastereoisomers 1C and 1D are considerably weaker and perceptible only by the most-sensitive persons. The same is true for a whole series of perceptual analogs of 1, including β-alkoxy alcohols. These ethers belong to two structural classes: [(2,2,6-trimethylcyclohexyl)oxy]- (see 3, 4, and 16) or {[2-(tert-butyl)cyclohexyl]oxy)alkan-2-ol derivatives (see 19 and 20; Table). A superimposition model allowing for good overlap of the respective hydroxylated side chains offers a tentative explanation for the shared perceptual characteristics of the two classes (Fig. 5). The lipophilic cyclohexane moieties present only a minimal overlap in this model, suggesting that quite larger molecules might possess the same smell. (S)-Configured β-alkoxy alcohols can conveniently be obtained on a larger scale by enantioselective reduction of the corresponding ketones (Scheme 9).
α-Chlorination of Carboxylic Acids Using Trichloroisocyanuric Acid
Hiegel, Gene A.,Faher, Diane Dutton,Lewis, Justin C.,Tran, Tan Duc,Hobson, Gregory G.,Farokhi, Farhad
, p. 889 - 893 (2007/10/03)
Carboxylic acids are chlorinated in the a position by heating with trichloroisocyanuric acid after formation of a small amount of the acid chloride using phosphorus trichloride.
Direct Organocatalytic Asymmetric α-Chlorination of Aldehydes
Halland, Nis,Braunton, Alan,Bachmann, Stephan,Marigo, Mauro,Jorgensen, Karl Anker
, p. 4790 - 4791 (2007/10/03)
The direct organocatalytic enantioselective α-chlorination of aldehydes has been developed. The reaction proceeds for a series of different aldehydes with NCS as the chlorine source using easily available catalysts such as L-proline amide and (2R,5R)-diphenylpyrrolidine. The α-chloro aldehydes are obtained in up to 99% yield and up to 95% ee. The synthetic utility of the enantioselective α-chlorination of aldehydes is demonstrated by transformation of the α-chloro aldehydes to the corresponding α-chloro alcohols (>90% yield) by standard reduction and further transformation to both a terminal epoxide and amino alcohol, both obtained without loss of optical purity. Oxidation of the α-chloro aldehydes followed by esterification gave optically active α-chloro esters without loss of optical purity. It is demonstrated that these optically active α-chloro esters can be converted into nonproteinogenic amino acids in overall high yields, maintaining the enantiomeric excess obtained in the catalytic enantioselective α-chlorination step. Copyright
