2901-13-5Relevant articles and documents
Dienolates of Cycloalkenones and α,β-Unsaturated Esters Form Diels–Alder Adducts by a Michael/Michael-Tandem Reaction Rather Than in One Step
Loesche, Ann-Christine,Brückner, Reinhard
supporting information, p. 562 - 573 (2018/12/11)
α,β-Unsaturated esters and lithium 1,3-dien-2-olates are known to furnish bicyclic lithium enolates by anionic Diels–Alder reactions. However, in principle, the respective products might form not only in a single step but also in two consecutive – or “tandem” – Michael additions, the first of which occurs intermolecularly, the second intramolecularly. Three cyclic lithium dienolates and four esters with a stereogenic Cα=Cβ bond reacted to give Diels–Alder adducts (10 times) or failed to react (2 times). Seven of the reactive combinations furnished adducts wherein the configuration of the former ester moiety had in part inverted. This precludes concerted pathways as their origins. This was a surprise since donors at C-2 of the 1,3-diene accelerate normal electron-demand Diels–Alder reactions in the order alkyl ⊕O? being a far better donor still, it is not obvious why the mechanism is non-concerted rather than concerted (and still more asynchronous).
Facile synthesis of 2-aryl or β,γ-unsaturated esters via 1,2-Migration from aryl or α,β-unsaturated ketones using thallium(III) p-tosylate
Lee, Jae In
, p. 125 - 128 (2017/06/07)
The experiment reports that 2-aryl esters can be efficiently synthesized via 1,2-aryl migration from aryl ketones using thallium(III) p-tosylate in high yields. To determine optimum conditions for conversion of aryl ketones to 2-aryl esters, the effects of solvents were examined. An initial reaction of 4'-methoxypropiophenone and perchloric acid using thallium(III) p-tosylate in ethanol afforded ethyl 2-(4-methoxyphenyl)propanoate in only 10% yield after 24 h at room temperature. However, the corresponding reaction in ethanol/triethyl orthoformate (4/1) was completed in 1 h between 0 °C and room temperature to give ethyl 2-(4-methoxyphenyl)propanoate in 94% yield. The presence of triethyl orthoformate induced rapid ketalization of enol intermediate and facilitated 1,2-migration of the 4-methoxyphenyl group. The relative effectiveness of several metal salts was also examined for conversion of 2',4'-dimethoxypropiophenone to ethyl 2-(2,4-dimethoxyphenyl)propanoate. The solvents were evaporated off under reduced pressure, and the residue was dissolved in methylene chloride. The white precipitate was filtered off, and the resulting yellow solution was poured into saturated NaHCO3 solution and extracted with methylene chloride. The combined organic layers were dried over anhydrous MgSO4, filtered, and concentrated in vacuo. The residue was purified by vacuum distillation using a Kugelrohr apparatus to give 4g as a colorless liquid.
compared to the Russ sandbank method for the preparation of key intermediate
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Paragraph 0027; 0028, (2016/10/07)
The invention discloses a preparation method of a bilastine key intermediate 2-(4-ethoxy)-phenyl-2-methyl propionate. The method comprises the following steps: carrying out carbonyl reducing reaction on 2-(4-haloacetyl)-phenyl-2-methyl propionate under th
A fexofenadine hydrochloride process for synthesizing
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Paragraph 0017; 0018, (2017/02/17)
The invention discloses a synthetic process of fexofenadine hydrochloride. The synthetic process of fexofenadine hydrochloride comprises the following steps of: with alpha, alpha-dimethyl phenylacetic acid as a raw material, carrying out an esterification reaction on alpha, alpha-dimethyl phenylacetic acid and absolute ethyl alcohol under the catalysis of a silica gel loaded phosphotungstic acid (PW12/SiO2) solid acid catalyst to obtain alpha, alpha-dimethyl ethyl phenylacetate; carrying out Friedel-Grafts reaction on alpha, alpha-dimethyl ethyl phenylacetate and 4-chlorobutyryl chloride to obtain alpha, alpha-dimethyl-4-(4-chloro-1-oxo butyl) ethyl phenylacetate; reducing by virtue of sodium borohydride in 95% ethyl alcohol to obtain alpha, alpha-dimethyl-4-(4-chloro-1-hydroxyl butyl) ethyl phenylacetate; and carrying out N-alkylation reaction on alpha, alpha-dimethyl-4-(4-chloro-1-hydroxyl butyl) ethyl phenylacetate and alpha, alpha-dimethyl-4-piperidine methyl alcohol in DMF (dimethyl formamide) for 24 hours at the temperature of 80 DEG C to obtain alpha, alpha-dimethyl-4-[1-hydroxyl-4-[4-(hydroxyl diphenylmethyl)-1-piperidyl]-butyl] ethyl phenylacetate, and then carrying out alkali hydrolysis and salification by virtue of hydrochloric acid, so that fexofenadine hydrochloride is obtained. The synthetic process of fexofenadine hydrochloride is high in yield and low in cost, produces less pollution and is applicable to industrial mass production.
3,3-Dimethyl-1H-pyrrolo[3,2-g]quinolin-2(3H)-one derivatives as novel Raf kinase inhibitors
Li, Yanyang,Shi, Xiangfei,Xie, Ning,Zhao, Yanjin,Li, Shuxin
, p. 367 - 370 (2013/06/05)
A series of quinoline derivatives were designed and synthesized as tyrosine kinase inhibitors. Exploration of the structure-activity relationships resulted in compounds that are potent in vitro. In addition, compound 10f was found to be a potent and selec
Generation of carbanions through stibine-metal and bismuthine-metal exchange reactions and its applications to precision synthesis of ω-end-functionalized polymers
Kayahara, Eiichi,Yamada, Hiroto,Yamago, Shigeru
supporting information; experimental part, p. 5272 - 5280 (2011/06/20)
Generation of carbanions from organostibines and organobismuthines through heteroatom-metal exchange reactions was examined from synthetic and mechanistic viewpoints. The exchange reaction proceeded spontaneously upon treatment with various organometallic reagents, such as alkyl lithiums, tetraalkyl zincates, and alkyl magnesium halides to afford the corresponding carbanions quantitatively. Due to the high reactivity of these heteroatom compounds, the exchange reactions took place exclusively even in the presence of various polar functional groups, which potentially react with organometallic species. The advantage of this method was exemplified by the end-group transformation of living polymers that bear these heteroatom species at the ω-polymer end, prepared by using organostibine and bismuthine-mediated living radical polymerizations. Various polymers that bear polar functional groups and acidic hydrogen-for example, poly(methyl methacrylate), poly(butyl acrylate), poly(N-isopropyl acrylamide), and poly(2-hydroxyethyl methacrylate)-could be used in the exchange reactions, and subsequent trapping with electrophiles afforded the corresponding polymers with controlled molecular weights, molecular weight distributions, and end-group functionalities. Competition experiments showed that organostibines and organobismuthines were among the most reactive heteroatom compounds towards organometallic reagents and that their high reactivity was responsible for the high chemoselectivity in the exchange reaction. All's well that ends well: The generation of carbanions from organostibine and -bismuthine compounds was achieved thorough a heteroatom-metal exchange reaction (see scheme). The highly chemoselective exchange reaction could be applied to precision synthesis of varieties of ω-end- functionalized polymers that possess a polar functional group.
Triphenylphosphine dibromide: a simple one-pot esterification reagent
Salomé, Christophe,Kohn, Harold
supporting information; experimental part, p. 456 - 460 (2009/04/06)
We report a one-pot, expedient protocol for the conversion of carboxylic acids to their esters using excess triphenylphosphine dibromide, base, and the alcohol. The reaction gave the esterified product in moderate-to-high yields (30-95%). For chiral acids, the reaction proceeded with little or no racemization. Use of a chiral alcohol in this transformation gave the ester with retention of configuration of the stereogenic center. Information is presented indicating that esterification proceeds through the intermediate generation of an acyloxyalkoxyphosphorane and where steric interactions play an important role in the energetics of the reaction.
COMPOUNDS USEFUL AS PHOSPHOTYROSINE MIMICS
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Page 15, (2010/02/07)
New uses are disclosed for compositions containing compounds of formula (I) wherein A, B, C, G, Q and R are defined herein. The compositions inhibit the binding of tyrosine kinase-dependent regulatory proteins to their native phosphotyrosine-containing li
New Synthetic Methods for Seven- and Eight-Membered Cyclic Ethers Based on the Ring-Expansion Reactions of Hydroxy or Lithioxy Methoxyallenylisochroman Derivatives
Nagao, Yoshimitsu,Tanaka, Satoru,Hayashi, Kazuhiko,Sano, Shigeki,Shiro, Motoo
, p. 481 - 484 (2007/10/03)
The Pd(0)-catalyzed ring-expansion reactions of hydroxy methoxyallenyl-4,4-dialkylisochroman derivatives in the presence of P(o-tolyl)3 proceeded smoothly via hydropalladation to give 3-benzoxepan-1-one derivatives in high yields. Treatment of
Fluorotetraphenylbismuth: A new reagent for efficient regioselective α-phenylation of carbonyl compounds
Ooi, Takashi,Goto, Ryoji,Maruoka, Keiji
, p. 10494 - 10495 (2007/10/03)
Synthesis and X-ray crystallographic characterization of fluorotetraphenylbismuth (1) has been achieved for the first time, revealing that the bismuth center of 1 adopts a distorted trigonal bipyramidal geometry with three ipso carbons at the equatorial sites and one ipso carbon and fluorine atom at the apical sites. Contrary to the previous common understanding of this type of organobismuth(V) compound, 1 was found to be thermally stable, maintaining its amphiphilic property. Hence, 1 can be used as an off-the-shelf reagent in organic synthesis, and its utility has been clearly demonstrated in applications to the efficient α-phenylation of ketones and esters. For instance, simple mixing of 1 and 1-trimethylsiloxy-3,4-dihydronaphthalene in THF at -40 °C and stirring at room temperature for 10 min gave rise to 2-phenyl-1-tetralone almost quantitatively without formation of the polyphenylated products. In addition to the generality of this method, applicability of our approach to the selective α-alkenylation of carbonyl compounds was also demonstrated by the use of fluoro(2-phenylethenyl)tris(p-tolyl)bismuth (2) as a representative reagent. These results imply the vast potential of organobismuth(V) compounds of type 1 and 2 as useful precursors of a wide variety of pentavalent organobismuth compounds based on the utilization of the eminent fluorine-silicon interaction or the inherent basicity of the fluorine atom. Copyright
