- Asymmetric synthesis of 4(R)tert-butyl-8a(S)hydroxycarbonyl-4,6,7,8,8a,9-hexahydro-1-alkylpyrr olo[3,2-f]indolizines via intramolecular iminium ion cyclization
-
Enantiomerically pure compounds embodying the 4,6,7,8,8a,9-hexahydropyrrolo[3,2-f]indolizine unit were synthesized via intramolecular iminium ion cyclization. An improved procedure for the preparation of the oxazolidinone 1 is also reported.
- Annunziata, Rita,Ferrari, Marinella,Papeo, Gianluca,Resmini, Marina,Sisti, Massimo
-
-
Read Online
- Synthesis of new mono- and bisorganophosphorus proline derivatives with P–C–N moieties
-
The various methods of aminomethylation of some PH-acids with proline and their derivatives are investigated. The numerous derivatives of proline and corresponding phosphonates, phosphonites, phosphinates, and phosphorane with proline moieties are presented.
- Prishchenko, Andrey A.,Livantsov, Mikhail V.,Novikova, Olga P.,Livantsova, Ludmila I.,Petrosyan, Valery S.
-
-
- Synthesis of mono-and diphosphorus-substituted proline derivatives containing P–C–N fragments
-
Convenient methods for the synthesis of new types of mono-and diphosphorus-substituted proline derivatives containing P–C–N fragments were developed based on special pre-prepared proline-containing synthons. The corresponding organophosphorus acids including a proline fragment were also synthesized.
- Prishchenko,Livantsov,Novikova,Livantsova,Petrosyan
-
p. 1846 - 1854
(2017/03/22)
-
- Compositions for Treatment of Cystic Fibrosis and Other Chronic Diseases
-
The present invention relates to pharmaceutical compositions comprising an inhibitor of epithelial sodium channel activity in combination with at least one ABC Transporter modulator compound of Formula A, Formula B, Formula C, or Formula D. The invention also relates to pharmaceutical formulations thereof, and to methods of using such compositions in the treatment of CFTR mediated diseases, particularly cystic fibrosis using the pharmaceutical combination compositions.
- -
-
Paragraph 1218
(2015/09/22)
-
- Novel catalysts for the enantioselective Henry reaction
-
Two novel catalytic systems based on the CuII complexes with N-(3,5-dibromo-2-hydroxybenzyl)- and N-(2-hydroxy-3-nitrobenzyl)-(S)-α,α-diphenylprolinols were developed. These systems catalyze the condensation of 4-nitrobenzaldehyde with nitromethane to produce S-nitroaldol with maximum enantiomeric excess of >90% (99% yield). The reactions of nitromethane with aliphatic aldehydes give the corresponding products in the yields above 80% and ee > 90%.
- Veselovsky,Stepanov
-
p. 422 - 425
(2015/02/02)
-
- δ13C analysis of amino acids in human hair using trimethylsilyl derivatives and gas chromatography/combustion/isotope ratio mass spectrometry
-
RATIONALE To provide a simple one-step derivatization procedure for the analysis of a wide variety of amino acids in human hair by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization is already widely used outside the IRMS community, is applicable to a variety of functional groups, and provides products that are common entries in mass spectral databases, thus simplifying compound identification. METHODS Method optimization and validation were performed on a mixture of ten standard amino acids found abundantly in human hair. The method was then applied to the analysis of scalp hair from six human subjects. The hair was washed, hydrolyzed with 6 M HCl, derivatized using BSTFA in acetonitrile and analyzed using gas chromatography (GC) with concurrent quadrupole and isotope ratio mass spectrometry (IRMS) detectors. RESULTS The reproducibility for the δ13C measurements, including the derivatization procedure and GC/C/IRMS analysis, on a day-to-day comparison was between 0.19‰ and 0.35‰ (SD, N = 12), with an average standard deviation of 0.26‰. Because trimethylsilylation adds 3N carbon atoms (where N = # reactive protons) to each amino acid, the δ13C values for amino acid derivatives were corrected using a mass balance correction and the measured kinetic isotope effect (KIE). The KIE values ranged from 0.984 to 1.020. CONCLUSIONS The procedure gave consistent δ13C values with precision similar to other derivatization methods for the range of sample sizes studied: 50-1000 μg of each amino acid. The method gave δ13C values consistent with the known literature values when applied to the analysis of amino acids in human hair. Copyright 2013 John Wiley & Sons, Ltd. Copyright
- An, Yan,Schwartz, Zeland,Jackson, Glen P.
-
p. 1481 - 1489
(2013/07/27)
-
- HOBt·DCHA-mediated synthesis of sterically hindered peptides employing Fmoc-amino acid chlorides in both solution-phase and solid phase methods
-
The synthesis of peptides employing Fmoc-amino acid chlorides in presence of HOBt·DCHA salt in solution as well as by the solid-phase methods is described. The coupling was found to be complete in 30 min and free from racemization. The synthesis of β-casomorphin by solid-phase protocol employing Fmoc-amino acid chloride/HOBt·DCHA in DMF-CH2Cl2 has also been outlined. The final peptide was obtained in 80% yield and was fully characterized. Copyright Taylor & Francis Group, LLC.
- Sureshbabu, Vommina V.,Sudarshan, Naremaddepalli S.,Chenna Krishna
-
p. 2625 - 2637
(2008/12/22)
-
- Are oxazolidinones really unproductive, parasitic species in proline catalysis? - Thoughts and experiments pointing to an alternative view
-
The N,O-acetal and N,O-ketal derivatives (oxazolidinones) formed from proline, and aldehydes or ketones are well-known today, and they are detectable in reaction mixtures involving proline catalysis, where they have been considered 'parasitic dead ends'. We disclose results of experiments performed in the early 1970's, and we describe more recent findings about the isolation, characterization, and reactions of the oxazolidinone derived from proline and cyclohexanone. This oxazolidinone reacts (THF, room temperature) with the electrophiles β-nitrostyrene and chloral (=trichloroacetaldehyde), to give the Michael and aldol adduct, respectively, after aqueous workup (Scheme 5). The reactions occur even at -75° when catalyzed with bases such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or EtN(i-Pr)2 (DIPEA) (10%; Table 1). It is shown by NMR (Figs. 1 and 3) and IR analysis (Figs. 2 and 4) that the primarily detectable product (before hydrolysis) of the reaction with the nitro-olefin is again an oxazolidinone. When dissolved in hydroxylic solvents such as MeOH, 'hexafluoroisopropanol' ((CF3) 2CHOH; HFIP), AcOH, CF3COOH, or in LiBr-saturated THF, the ring of the oxazolidinone from cyclohexanone and proline opens up to the corresponding iminium ion (Tables 2-4), and when treated with strong bases such as DBU (in (D8)THF) the enamino-carboxylate derived from proline and cyclohexanone is formed (Scheme 8). Thus, the two hitherto putative participants (iminium ion and enamine) of the catalytic cycle (Scheme 9) have been characterized for the first time. The commonly accepted mechanism of the stereoselective C,C- or C,X-bond-forming step (i.e., A-D) of this cycle is discussed and challenged by thoughts about an alternative model with a pivotal role of oxazolidinones in the regio- and diastereoselective formation of the intermediate enamino acid (by elimination) and in the subsequent reaction with an electrophile (by trans-addition with lactonization; Schemes 11-14). The stereochemical bias between endo- and exo-space of the bicyclo[3.3.0]octane-type oxazolidinone structure (Figs. 5 and 6) is considered to possibly be decisive for the stereochemical course of events. Finally, the remarkable consistency, with which the diastereotopic Re-face of the double bond of pyrrolidino-enamines (derived from proline) is attacked by electrophiles (Schemes 1 and 15), and the likewise consistent reversal to the Si-face with bulky (Aryl) 2C-substituents on the pyrrolidine ring (Scheme 16) are discussed by invoking stereoelectronic assistance from the lone pair of pyramidalized enamine N-atoms.
- Seebach, Dieter,Beck, Albert K.,Badine, D. Michael,Limbach, Michael,Eschenmoser, Albert,Treasurywala, Adi M.,Hobi, Reinhard,Prikoszovich, Walter,Linder, Bernard
-
p. 425 - 471
(2008/02/07)
-
- Synthesis of Nα-protected peptide acids by the N→ C chain extension employing O,N-bis-trimethylsilyl-amino acids using the mixed anhydride method
-
Synthesis of Nα-protected peptide acids employing N→C extension strategy using in situ generated X-NH-CHR′-CO-O-CO- iBu and O,N-bis-trimethylsilyl-amino acids has been accomplished. The coupling is very rapid and efficient. The yield
- Tantry, Subramanyam J.,Babu, Vommina V. Suresh
-
p. 1282 - 1287
(2007/10/03)
-
- Chemoenzymatic synthesis of a characteristic phosphorylated and glycosylated peptide fragment of the large subunit of mammalian RNA polymerase II
-
The covalent modification of proteins by phosphorylation and addition of GlcNAc residues are important regulatory processes which mediate biological signal transduction. For instance, the cytosolic form of RNA polymerase II is heavily glycosylated but dur
- Pohl, Torsten,Waldmann, Herbert
-
p. 6702 - 6710
(2007/10/03)
-
- SYNTHESIS OF SOME SILICON- AND PHOSPHORUS-SUBSTITUTED DERIVATIVES OF PROLINE
-
On the basis of L-proline methyl ester its N-substituted derivatives were obtained, which included an alkoxymethyl, trimethylsilyl, or diethoxyphosphinomethyl group.The reaction of proline methyl ester with paraform results in bismethane.The latter was used for synthesis of a phosphinate containing two fragments of proline by double aminomethylation of bis(trimethylsiloxy)phosphine.
- Prishchenko, A. A.,Livantsov, M. V.,Pisarnitskii, D. A.,Petrosyan, V. S.
-
p. 1410 - 1413
(2007/10/02)
-
- ENANTIOMERIC QUANTIFICATIONS OF AMINO ACIDS THROUGH THEIR Nα-ACYL AMIDES BY GAS CHROMATOGRAPHY.
-
Apparent separation of 1.1 or higher on Chirasil Val III can be obtained for Nα-acyl N-alkyl aminoacid amides allowing the use of short capillary gas chromatographic columns.A clean derivatization protocol without racemization is described, proceding through the NCA derivatives that are prepared from "in situ" silylated amino acids with trimethylsilyl cyanide.
- Hosten, N.,Antenuis, M.J.O
-
-