1522-46-9Relevant academic research and scientific papers
Note on the Determination of the Absolute Configuration of (+)-2-Hydroxy-2,3-dimethylbutyric Acid
Wetter, Hansjuerg
, p. 761 - 768 (1981)
Chemical correlation of the title compound 1 with (S)-3-isopropyl-3-methyl-5-trimethylsilyl-4-penten-2-one (2) showed (+)-1 to have (S)-configuration.Key step was the Baeyer-Villiger oxidation of a very hindered, optically active methyl keton to the corresponding acetoxy compound with trifluoroperacetic acid using slightly modified buffer conditions.It is found, that the erythro/threo assignment of an α,α-disubstituted β-hydroxyester intermediate can be based on the observation, that the 1H-NMR signal of H-C(β) of the erythro isomer appears at lower field than that of the threo isomer.
MODULATOR OF CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR, PHARMACEUTICAL COMPOSITIONS, METHODS OF TREATMENT, AND PROCESS FOR MAKING THE MODULATOR
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Page/Page column 172, (2018/06/30)
Compounds of Formula (I) pharmaceutically acceptable salts thereof, deuterated derivatives of any of the foregoing, and metabolites of any of the foregoing are disclosed. Pharmaceutical compositions comprising the same, methods of treating cystic fibrosis using the same, and methods for making the same are also disclosed. Also disclosed are solid state forms of Compound 1 and salts and solvates thereof.
Construction of All-Carbon Quaternary Centers through Cu-Catalyzed Sequential Carbene Migratory Insertion and Nucleophilic Substitution/Michael Addition
Wang, Chengpeng,Ye, Fei,Wu, Chenggui,Zhang, Yan,Wang, Jianbo
, p. 8748 - 8757 (2015/09/15)
A Cu-catalyzed three-component cross-coupling reaction of terminal alkyne, α-diazo ester, and alkyl halide has been developed. This transformation involves sequent migratory insertion of copper-carbene and nucleophilic substitution, in which a C(sp)-C(sp3) bond and a C(sp3)-C(sp3) bond are formed successively on a carbenic center. Michael addition acceptors can also be employed instead of alkyl halides that enable Michael addition to be an alternative way to build C(sp3)-C(sp3) bond. This transformation represents a highly efficient method for the construction of all-carbon quaternary centers.
Catalytic asymmetric synthesis of trisubstituted aziridines
Huang, Li,Wulff, William D.
supporting information; experimental part, p. 8892 - 8895 (2011/08/04)
A method is described which provides for the direct asymmetric catalytic synthesis of trisubstituted aziridines from imines and diazo compounds. While unactivated imines were not reactive to α-diazo carbonyl compounds in which the diazo carbon was disubstituted, N-Boc imines react with both α-diazo esters and α-diazo-N-acyloxazolidinones to give trisubstituted aziridines with excellent diastereo- and enantioselectivities.
Asymmetric synthesis of β2-amino acids: 2-substituted-3-aminopropanoic acids from N-acryloyl SuperQuat derivatives
Beddow, James E.,Davies, Stephen G.,Ling, Kenneth B.,Roberts, Paul M.,Russell, Angela J.,Smith, Andrew D.,Thomson, James E.
, p. 2812 - 2825 (2008/03/12)
Conjugate addition of lithium dibenzylamide to (S)-N(3)-acryloyl-4- isopropyl-5,5-dimethyloxazolidin-2-one (derived from l-valine) and alkylation of the resultant lithium β-amino enolate provides, after deprotection, a range of (S)-2-alkyl-3-aminopropanoic acids in good yield and high ee. Alternatively, via a complementary pathway, conjugate addition of a range of secondary lithium amides to (S)-N(3)-(2′-alkylacryloyl)-4-isopropyl-5,5- dimethyloxazolidin-2-ones, diastereoselective protonation with 2-pyridone, and subsequent deprotection furnishes a range of (R)-2-alkyl- and (R)-2-aryl-3-aminopropanoic acids in good yield and high ee. Additionally, the boron-mediated aldol reaction of β-amino N-acyl oxazolidinones is a highly diastereoselective method for the synthesis of a range of β-amino- β′-hydroxy N-acyl oxazolidinones. The Royal Society of Chemistry.
Asymmetric synthesis of 2-substituted butane-1,4-diols by hydrogenation of homochiral fumaramide derivatives
Jawaid, Samaila,Farrugia, Louis J.,Robins, David J.
, p. 3979 - 3988 (2007/10/03)
Diastereoselective hydrogenation of homochiral fumaramides 1 derived from (2R)-Oppolzer's sultam was observed by analysis of the 1H NMR spectra of the succinamide mixtures with de's of 77-88%. Reduction of these succinamides using LiAlH4 gave the corresponding (2S)-butane-1,4- diols and established that addition of hydrogen takes place selectively on the re-face of fumaramides 1. The stereoselectivity was confirmed by estimating the ee's from the 19F NMR spectra of the Mosher's diesters of the diols. This methodology was applied to the synthesis of selected pyrrolidine natural products in homochiral form.
Use of the Nonionic Superbase P(MeNCH2CH2)3N in the Selective Monoalkylation of Active-Methylene Compounds
Arumugam, Subramaniam,McLeod, Dale,Verkade, John G.
, p. 3677 - 3679 (2007/10/03)
The symmetric active-methylene compounds CH2(CO2Et)2 and CH2[C(O)Me]2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic Superbase P(MeNCH2CH2)2N in 85-98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO2CCH2C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59-88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH2CH2)2N+ counterion in a tight ion pair.
Enantiospecific synthesis of (+)- and (-)-trachelanthic acids via asymmetric dihydroxylation and their conversion to the pyrrolizidine alkaloids indicine and intermedine
Nambu, Mitch,White, James D.
, p. 1619 - 1620 (2007/10/03)
Asymmetric dihydroxylation of (E)-ethyl 2-isopropylbut-2-enoate with AD-mix-a and AD-mix-P, followed by saponification, gives (-)- and (+)-trachelanthic acids, respectively, which are each coupled via their acetonides with (+)-retronecine to yield the pyrrolizidine alkaloids indicine and intermedine.
On the conjugate addition of tetraorganothallium ate complexes
Marko,Rebiere
, p. 1763 - 1766 (2007/10/02)
Tetraorganothallium ate complexes have been prepared and reacted with enones to afford either the [1,2] or [1,4] addition product. Mixed ate complexes display high levels of chemoselectivity in the transfer of one of their ligands.
Charge-reversal Mass Spectra of Enolate Ions of Some Open-chain and Cyclic Ketones for Structure Identification
Suerig, Thomas,Gruetzmacher, Hans-Friedrich
, p. 446 - 452 (2007/10/02)
The charge-reversal (CR) mass spectra of the enolate ions of heptanal and ten isomeric heptanones, of cyclohexanone, of cycloheptanone, of isomeric methylcyclohexanones, of isomeric ethylcyclohexanones and of the isomeric monoterpene ketones camphor, fenchone, pulegone and thujone were obtained by deprotonating using OH(-) under chemical ionization conditions followed by collision of the (-) ions with helium in the second field-free region of a VG ZAB 2F mass spectrometer.The CR mass spectra were evaluated by similarity index (SI) values.Characteristic of the CR mass spectra of the open-chain enolates are fragment ions formed by α- cleavage.However, the CR mass spectra are dominated by peaks of small hydrocarbon ions, particularly in the case of cyclic and bicyclic enolates.The CR mass spectra of enolates of linear heptanones differing in the position of the carbonyl group can be easily correlated with the structure of the parent ketone.The CR mass spectra of enolates of isomeric heptan-2-ones differing only in the degree of branching of the alkyl group are similar, but can be distinguished by the SI values.The CR mass spectra of the enolates of the isomeric cyclic and bicyclic ketones studied are more or less identical and cannot be used for structural assignment.
