- Synthesis, Molecular Structure, and Spectroscopical Properties of Alkenylphosphonic Derivatives. 1. Vinyl-, Propenyl-, (Bromoalkenyl)-, and (Cyanoalkenyl)phosphonic Compounds
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Several vinyl-, propenyl-, (bromoalkenyl)-, and (cyanoalkenyl)phosphonate derivatives have been synthesized.The (2-cyanovinyl)phosphonates have been obtained with an important improvement in the yield (40percent versus 6percent).The separation of the E and Z isomers of the cyano derivatives and their hydrolysis to the corresponding phosphonic acids have been studied.The bromination and dehydrobromination of some alkenylphosphonic derivatives have also been studied.Spectroscopical studies from UV, IR, Raman, and 1H, 13C, and 31P NMR have been performed in most of these derivatives.The C=C/P=O ? conjugation exists but it is weak in all these compounds.Dipole moments and C=C/P=O conformational populations have been calculated theoretically by ab initio methods.The effect of the solvent polarity on the conformational population has been observed by IR spectroscopy disclosing two C=C/P=O conformers.Experimental and theoretical results have been compared, a high level of agreement has been found.
- Sainz-Diaz, C. I.,Galvez-Ruano, E.,Hernandez-Laguna, A.,Bellanato, J.
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- N-Vinyl and N-Aryl Hydroxypyridinium Ions: Charge-Activated Catalysts with Electron-Withdrawing Groups
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Charge-enhanced Br?nsted acid organocatalysts with electron-withdrawing substituents were synthesized, and their relative acidities were characterized by computations, 1:1 binding equilibrium constants (K1:1) with a UV-vis active sensor, 31P NMR shifts upon coordination with triethylphosphine oxide, and in one case by infrared spectroscopy. Pseudo-first-order rate constants were determined for the Friedel-Crafts alkylations of N-methylindole with trans-β-nitrostyrene and 2,2,2-trifluoroacetophenone and the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone. These results along with kinetic isotope effect determinations revealed that the rate-determining step in the Friedel-Crafts transformations can shift from carbon-carbon bond formation to proton transfer to the catalyst's conjugate base. This leads to an inverted parabolic reaction rate profile and slower reactions with more acidic catalysts in some cases. Electron-withdrawing groups placed on the N-vinyl and N-aryl substituents of hydroxypyridinium ion salts lead to enhanced acidities, more acidic catalysts than trifluoroacetic acid, and a linear correlation between the logarithms of the Diels-Alder rate constants and measured K1:1 values.
- Riegel, George F.,Kass, Steven R.
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p. 6017 - 6026
(2020/05/26)
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- Method for efficiently synthesizing N-3-isooxazole tert-butyl carbamate
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The invention discloses a method for efficiently synthesizing N-3-isooxazole tert-butyl carbamate. The synthetic route comprises the following steps: brominating a compound A to obtain a compound B, and reacting the compound B and a compound C to obtain a compound D; and reacting the compound D and di-tert-butyl dicarbonate ester, thereby obtaining the compound E. The reaction formula is as shownin the specification. The process method for synthesizing 3-aminoisoxazole is simple in process, cheap and readily available in raw materials, simple and convenient in operation and extremely suitablefor large-scale industrial production, and has very wide industrial application prospects and market value.
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Paragraph 0030; 0032
(2019/03/08)
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- How Reaction Conditions May Influence the Regioselectivity in the Synthesis of 2,3-Dihydro-1,4-benzoxathiine Derivatives
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The exploration of different reaction conditions aiming to obtain both 2,3-dihydro-1,4-benzoxathiine-2-yl derivatives and 2,3-dihydro-1,4-benzoxathiine-3-yl ones is reported. The treatment of 1,2-mercaptophenol with an organic base and a specific 2-bromo acrylate results in a solvent- and substrate-dependent exclusive solvation of O- and S-anions, thus managing the regioselectivity.
- Casiraghi, Andrea,Valoti, Ermanno,Suigo, Lorenzo,Artasensi, Angelica,Sorvillo, Erica,Straniero, Valentina
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p. 13217 - 13227
(2018/10/24)
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- Characterization of an indole-3-acetamide hydrolase from alcaligenes faecalis subsp. parafaecalis and its application in efficient preparation of both enantiomers of chiral building block 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid
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Both the enantiomers of 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid are valuable chiral synthons for enantiospecific synthesis of therapeutic agents such as (S)-doxazosin mesylate, WB 4101, MKC 242, 2,3-dihydro-2-hydroxymethyl-1,4-benzodioxin, and N-[2,4-oxo-1,3-thiazolidin-3-yl]-2,3-dihydro-1,4-benzodioxin-2-carboxamide. Pharmaceutical applications require these enantiomers in optically pure form. However, currently available methods suffer from one drawback or other, such as low efficiency, uncommon and not so easily accessible chiral resolving agent and less than optimal enantiomeric purity. Our interest in finding a biocatalyst for efficient production of enantiomerically pure 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid lead us to discover an amidase activity from Alcaligenes faecalis subsp. parafaecalis, which was able to kinetically resolve 2,3-dihydro-1,4-benzodioxin-2-carboxyamide with E value of >200. Thus, at about 50% conversion, (R)-2,3-dihydro-1,4-benzodioxin-2-carboxylic acid was produced in >99% e.e. The remaining amide had (S)-configuration and 99% e.e. The amide and acid were easily separated by aqueous (alkaline)-organic two phase extraction method. The same amidase was able to catalyse, albeit at much lower rate the hydrolysis of (S)-amide to (S)-acid without loss of e.e. The amidase activity was identified as indole-3-acetamide hydrolase (IaaH). IaaH is known to catalyse conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA), which is phytohormone of auxin class and is widespread among plants and bacteria that inhabit plant rhizosphere. IaaH exhibited high activity for 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which was about 65% compared to its natural substrate, indole-3-acetamide. The natural substrate for IaaH indole-3-acetamide shared, at least in part a similar bicyclic structure with 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which may account for high activity of enzyme towards this un-natural substrate. To the best of our knowledge this is the first application of IaaH in production of industrially important molecules.
- Mishra, Pradeep,Kaur, Suneet,Sharma, Amar Nath,Jolly, Ravinder S.
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- New functionalized dithia-12(13)-crown-4 ethers: Synthesis, complex formation, and extraction capacity
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1,4-Dioxa-7,10-dithiacyclododecane-8-carbonitrile, 1,4-dioxa-7,11- dithiacyclotridecan-9-one, its 2,4-dinitrophenylhydrazone, and unsubstituted 7,10-dithia-12-crown-4 were synthesized. The complexing ability of the four synthesized dioxadithiacrown compounds toward Ag(I), Pb(II), Hg(II), and Cd(II) ions was assessed by 1H NMR. The extracting ability of the three dioxadithiacrown compounds with respect to the Sn(II) ion from aqueous solutions was studied. The thermal stability of 1,4-dioxa-7,10-dithia-cyclododecane and the corresponding 8-carbonitrile was investigated.
- Zenina,Rakhmanov,Bobyleva,Lukovskaya,Kuzmina,Abramov,Anisimov
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p. 835 - 843
(2008/09/18)
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- An economical and convenient synthesis of vinyl sulfones
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A general process for the efficient synthesis of vinyl sulfones has been developed using commercially available sulfinic acid sodium salts and dibromides. A variety of phenyl and methyl vinyl sulfones have been formed in good yields, in the absence of any catalyst. Georg Thieme Verlag Stuttgart.
- Guan, Zheng-Hui,Zuo, Wei,Zhao, Lian-Biao,Ren, Zhi-Hui,Liang, Yong-Min
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p. 1465 - 1470
(2008/02/05)
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- Domino Michael-O-alkylation reaction: One-pot synthesis of 2,4-diacylhydrofuran derivatives and its application to antitumor naphthofuran synthesis
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The one-pot synthesis of 2,4-diacylhydrofuran derivatives and its applications to antitumor napthofuran synthesis was discussed. It was found that the reaction of 1,3-dicarbonyl compounds with α-halo-α,β-unsaturated carbonyl compounds afforded 2,4-diacyldihydrofuran derivatives in the presence of DBU in THF. The analysis showed that the applications of the protocol enabled short-step synthesis of antitumor napthofuran natural products.
- Hagiwara, Hisahiro,Sato, Kouji,Nishino, Daisuke,Hoshi, Takashi,Suzuki, Toshio,Ando, Masayoshi
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p. 2946 - 2957
(2007/10/03)
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- Novel syntheses of indolizines and pyrrolo[2,1-a]isoquinolines via benzotriazole methodology
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Indolizines and pyrrolo[2,1-a]isoquinolines are synthesized by 1,3- dipolar cycloadditions of pyridinium benzotriazolylmethylides or isoquinolinium benzotriazolylmethylides with ethylenes and acetylenes.
- Katritzky, Alan R.,Qiu, Guofang,Yang, Baozhen,He, Hai-Ying
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p. 7618 - 7621
(2007/10/03)
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- Aqueous isothiazolone formulation
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An aqueous isothiazolone formulation useful for antiseptic or antifungal treatment of various synthetic polymeric emulsions, which comprises (a) a specific isothiazolone compound, (b) water or an aqueous solvent and (c) a specific nitrobromo or cyanobromo compound.
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- Chemistry of aziridinecarboxylic acids; Part 2. Convenient synthesis of 2-aminopropenenitrile
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2-Aminopropenenitrile (4) has been prepared by dehydrochlorination of 2-amino-3-chloropropanenitrile (3) with triethylamine. A simple and efficient synthesis of 2-cyanoaziridine (2) by reaction of 2,3-dibromopropanenitrile (1) with ammonia in methanol in the presence of triethanolamine is described.
- Jahnisch,Weight,Bosies
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p. 1211 - 1212
(2007/10/02)
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- An Improved Synthesis of 3-(1-Imidazolyl)-2-alkenoic Acid Derivatives and Related Compounds
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The preparative method of 3-(1-imidazolyl)-2-alkenoic acid derivatives and the related compounds was improved by the use of strong bases such as sodium hydride in DMF.By this improved method, the preparation of 2-substituted 3-(1-imidazolyl)-2-alkenoic acid derivatives was accomplished in good yields.
- Kashima, Choji,Yoshiwara, Nobutoshi,Tajima, Tadakuni,Omote, Yoshimori
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p. 1595 - 1596
(2007/10/02)
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- The Compounds Related to 3-(1-Imidazolyl)-2-alken-1-ones. Preparation and Reactions
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Compounds related to 3-(1-imidazolyl)-2-alken-1-ones, 3-(1-imidazolyl)-2-alkenoic acid derivatives and 2-alken-1-ones having heterocycles on the C-3 carbon were prepared.The reaction of nucleophiles with these compounds was also discussed.
- Kashima, Choji,Tajima, Tadakuni,Omote, Yoshimori
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p. 171 - 176
(2007/10/02)
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- Ambident Electrophilic Character of Thioxophosphoranesulphenyl Bromides =P(S)SBr. A Novel Observation of Electrophilic Addition to a Carbon-Carbon Double Bond
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The thioxophosphoranesulphenyl bromides (1) act as ambident electrophiles towards alkenes and react, depending on the structure of the alkene, to give either the normal addition products -SC(R1)(R2)CR3(R4)(Br) or 1,2-dibromides and -disulphides.
- Lopusinski, Andrzej,Michalski, Jan,Potrzebowski, Mark
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p. 1362 - 1364
(2007/10/02)
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