- Phosphine-catalyzed sequential (2+3)/(2+4) annulation of γ-vinyl allenoates: Access to the synthesis of chromeno[4,3-: B] pyrroles
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A phosphine-catalyzed cascade (2+3)/(2+4) cyclization reaction of γ-vinyl allenoates with aldimine esters has been developed to provide a series of chromeno[4,3-b]pyrrole derivatives that contain three contiguous stereogenic centers. The method gives a good yield, excellent chemoselectivity and diastereoselectivity under mild conditions.
- Huang, You,Li, Xiaohu
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supporting information
p. 9934 - 9937
(2021/10/12)
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- Phosphine-Catalyzed [3+2] Annulation of β-Sulfonamido-Substituted Enones with Sulfamate-Derived Cyclic Imines
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Phosphine-catalyzed [3+2] annulation of β-sulfonamido-substituted enones and sulfamate-derived cyclic imines has been developed, giving a series of imidazoline derivatives in moderate to excellent yields with good to excellent diastereoselectivities. A scale-up reaction worked well under mild reaction conditions. A possible mechanism was proposed on the basis of the results obtained.
- Shi, Wangyu,Zhou, Leijie,Mao, Biming,Wang, Qijun,Wang, Chang,Zhang, Cheng,Li, Xuefeng,Xiao, Yumei,Guo, Hongchao
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supporting information
p. 679 - 685
(2019/01/24)
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- Enantioselective Construction of Tetrahydroquinazoline Motifs via Palladium-Catalyzed [4 + 2] Cycloaddition of Vinyl Benzoxazinones with Sulfamate-Derived Cyclic Imines
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A palladium-catalyzed enantioselective [4 + 2] cycloaddition reaction of vinyl benzoxazinones with sulfamate-derived cyclic imines is described, affording the tetrahydroquinazolines bearing several functional rings in high yields (up to 99% yield) with good to excellent diastereoselectivities and excellent enantioselectivities (up to 96% ee). This reaction represents the first Pd-catalyzed asymmetric decarboxylative cycloaddition of vinyl benzoxazinones with imines.
- Wang, Chang,Li, Yan,Wu, Yang,Wang, Qijun,Shi, Wangyu,Yuan, Chunhao,Zhou, Leijie,Xiao, Yumei,Guo, Hongchao
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supporting information
p. 2880 - 2883
(2018/05/29)
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- Enantioselective synthesis of multisubstituted biaryl skeleton by chiral phosphoric acid catalyzed desymmetrization/kinetic resolution sequence
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Described herein is the enantioselective synthesis of multisubstituted biaryl derivatives by chiral phosphoric acid catalyzed asymmetric bromination. Two asymmetric reactions (desymmetrization and kinetic resolution) proceeded successively to afford chiral biaryls in excellent enantioselectivities (up to 99% ee). Both experimental and computational studies suggested that this excellent selectivity could be achieved via a highly organized hydrogen bond network among a substrate, a catalyst (chiral phosphoric acid), and a brominating reagent (N-bromophthalimide).
- Mori, Keiji,Ichikawa, Yuki,Kobayashi, Manato,Shibata, Yukihiro,Yamanaka, Masahiro,Akiyama, Takahiko
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supporting information
p. 3964 - 3970
(2013/04/24)
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- Efficient two-step synthesis of salicylaldehydes via directed ortho-lithiation of in situ N-silylated O-aryl N-isopropylcarbamates
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O-Aryl N-isopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, are subjected to an efficient ortho-lithiation protocol to afford the corresponding salicylaldehydes in a one-pot operation in high yields. Georg Thieme Verlag Stuttgart.
- Kauch, Matthias,Hoppe, Dieter
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p. 1575 - 1577
(2007/10/03)
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- One-pot synthesis of substituted catechols from the corresponding phenols
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Phenols are converted to salicylaldehydes with paraformaldehyde, MgCl 2-Et3N in THF, and when subsequently treated with aqueous NaOH and H2O2 afford the corresponding catechols. The sequence is conveniently carried out as a one-pot procedure.
- Hansen, Trond Vidar,Skatteb?l, Lars
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p. 3357 - 3358
(2007/10/03)
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- One-pot synthesis of ortho-hydroxycinnamate esters
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Phenols are converted to salicylaldehydes with paraformaldehyde, MgCl 2-Et3N in THF, and subsequent treatment with methyl (triphenylphosphoranylidene)acetate gave the corresponding methyl ortho-hydroxycinnamate derivatives. The sequence is conveniently carried out as a one-pot procedure.
- Anwar, Hany F.,Skatteb?l, Lars,Skramstad, Jan,Hansen, Trond Vidar
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p. 5285 - 5287
(2007/10/03)
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- 3-ARYLOXY/ THIO-2, 3-SUBSTITUTED PROPANAMINES AND THEIR USE IN INHIBITING SEROTONIN AND NOREPINEPHRINE REUPTAKE
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There is provided a compound of formula (I) wherein A is selected from -O- and -S-; X is selected from phenyl optionally substituted with up to 5 substituents each independently selected from halo, C1-C4 alkyl and C1-C4 alkoxy, thienyl optionally substituted with up to 3 substituents each independently selected from halo and C1-C4 alkyl, and C2-C8 alkyl, C2-C8 alkenyl, C3-C8 cycloalkyl and C4-C8 cycloalkylalkyl, each of which may be optionally substituted with up to 3 substituents each independently selected from halo, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkyl-S(O)n- where n is 0, 1 or 2, -CF3, -CN and -CONH2; Y is selected from phenyl, naphthyl, dihydrobenzothienyl, benzothiazolyl, benzoisothiazolyl, quinolyl, isoquinolyl, naphthyridyl, thienopyridyl, indanyl, 1,3-benzodioxolyl, benzothienyl, indolyl and benzofuranyl, each of which may be optionally substituted with up to 4 or, where possible, up to 5 substituents each independently selected from halo, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkyl-S(O)n- where n is 0, 1 or 2, nitro, acetyl, -CF3, -SCF3 and cyano; and when Y is indolyl it may be substituted or further substituted by an N-substituent selected from C1-C4 alkyl; Z is selected from OR3 or F, wherein R3 is selected from H, C1-C6 alkyl and phenyl C1-C6 alkyl; R1 and R2 are each independently H or C1-C4 alkyl; and pharmaceutically acceptable salts thereofwith the proviso that when Y is optionally substituted phenyl or optionally substituted 1,3-benzodioxolyl and Z is OR3 and X is optionally substituted phenyl then A is -S-.
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- Non-metallocene compounds, method for the production thereof and use of the same for the polymerisation of olefins
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The invention relates to a method for producing special transition metal compounds, to novel transition metal compounds and to the use of the same for the polymerisation of olefins.
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- Method for producing optically active salicylaldimine copper complex
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There is provided a method for producing an optically active salicylaldimine copper complex, which method is characterized in that an optically active amino alcohol compound represented by the following formula (1) is reacted with copper hydroxide (II) in an organic solvent. wherein R1 and R2 which are the same or different, each represent lower alkyl groups and the like which may be substituted, X1 and X2 which are the same or different, each represent a hydrogen atom, lower alkyl groups and the like, and the symbol * designates an asymmetric carbon atom.
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- Magnesium-mediated ortho-Specific Formylation and Formaldoximation of Phenols
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Deprotonation of phenols using magnesium methoxide, followed by distillative removal of free methanol and addition of paraformaldehyde results in ortho-specific magnesium mediated formylation to give the corresponding salicyladehyde magnesium salts, from which the salicylaldehydes can be isolated by acidic work-up.Addition of aq. hydroxylamine sulfate to the salicylaldehyde magnesium salt, in place of the acid work-up, gives the corresponding salicylaldoximes.
- Aldred, Robert,Johnston, Robert,Levin, Daniel,Neilan, James
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p. 1823 - 1832
(2007/10/02)
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- Etude des complexes du cobalt (II) transporteurs d'oxygene: Nouvelle synthese du fluoro-3 hydroxy-2 benzaldehyde
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Synthetic chelates of cobalt (II) derived from Schiff bases have remarkable behavior of reversibly absorbing and releasing molecular oxygene.Among these, bis (3-fluorosalicylaldehydeethylenediimide) Co (II) (fluomine: Formula A, X=F) is most interesting in allowing to isolate pure oxygen from air, because it absorbs with extreme rapidity 4.43percent of its weight of oxygen.Fluomine is easily prepared from 3-fluorosalicylaldehyde (3FSA), ethylenediamine and cobalt (II) chloride; but substances such as 3-substituted salicylaldehydes have proven to be extremely difficult to prepare in other than small laboratory quantities from the corresponding ortho-substituted phenol.Many author have prepared 3-fluorosalicylaldehyde, as described in patents, but often these syntheses are very long and the yields are generally less than 20percent.We now describe a new synthesis from o-fluorophenol.Nitration of o-fluorophenol with liquid nitrogen dioxide is convenient: - on the one hand, ortho-substitution to the hydroxyl group, is easy, -on the other hand, the para substituted by-product, is reinserted in the course of the synthesis, so that it is possible to minimize loss of the starting phenol, an expensive product. o-Fluorophenol 1 in solution in pentane, at about 0 deg C, is treated with liquid nitrogen dioxide (slight excess).The reaction is rapid and leads to 2-fluoro 6-nitrophenol 2 which remains in solution, and 2-fluoro 4-nitrophenol 7 which cristallizes rapidly (approximatively 50percent of each one). 2-Fluoro 6-nitrophenol 2 is converted into the anisole 3, the NO2 group of which is catalytically reduced by hydrogen into 3-fluoro 2-methoxy-aminobenzene 4.This amine 4 is diazotized, and treated with formaldoxime to lead to 3-fluoro 2-methoxybenzaldehyde 5 (Eb12 = 82 deg C). 3FSA is finally obtained by heating under reflux anisole 5 and a solution of hydrobromic acid (48percent). 2-Fluoro 4-nitrophenol 7 is converted in five steps into 3-fluoro 2-methoxyaminobenzene 4 by the same reactions as these used for its isomer.Finally the total yield of amine 4 from o-fluorophenol is 73percent, and 3FSA is obtained in 25percent yield.No primary amines are required during the isolation, so that no possible contamination of the final product is possible and therefore the fluomine prepared therefrom is not contaminated and deactivated.
- Aymes, Daniel J.,Paris, Michel R.
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p. 175 - 178
(2007/10/02)
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- Preparation of 3-fluorosalicylaldehyde
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3-Fluorosalicylaldehyde may be prepared in a more economical manner by alkylating o-fluorophenol with an allyl halide such as allyl chloride, thereafter rearranging the resultant o-fluorophenyl allyl ether to form allyl-o-fluorophenol. The latter compound is then isomerized to form propenyl-o-fluorophenol. Thereafter this compound is subjected to ozonolysis at a subambient temperature to form the desired compound, namely, 3-fluorosalicylaldehyde.
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- Process for the selective synthesis of salicylaldehydes
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The classical Reimer-Tiemann reaction for the synthesis of phenolic aldehydes has been modified from an aqueous to a non-aqueous system to provide an improved route for the formation of salicylaldehydes and, preferably, 3-substituted salicylaldehydes, e.g. 3-fluorosalicylaldehyde. Heretofore, compounds such as 3-substituted salicylaldehydes have proven to be extremely difficult to prepare in other than small laboratory quantities from the corresponding ortho-substituted phenol, since, in the final salicylaldehyde, each position ortho to the hydroxyl group contains substitution. In particular, with respect to 3-fluorosalicylaldehyde, one of the positions is occupied by the strongly electronegative fluorine atom so that the principal reaction product in the aqueous Reimer-Tiemann reaction has always been the para-isomer (3-fluoro-4-hydroxy-benzaldehyde), only negligible quantities of the desired ortho-isomer being obtained. In the process of the present invention, o-fluorophenol is caused to react with sodium hydroxide and chloroform in a hydrocarbon diluent (preferably benzene), maintaining the reaction under essentially anhydrous conditions by taking up the water of reaction with excess sodium hydroxide. It is necessary that an aprotic solvent, such as N,N-dimethylformamide, be employed as a catalyst. The use of boron oxide, while not absolutely necessary to the reaction, has been found to be advantageous in that the reaction proceeds more smoothly if the phenoxyboroxine is formed initially. The boron oxide also acts as a dehydrating agent and aids in removing the water of reaction. The preferential reaction product is the desired 3-fluorosalicylaldehyde, no paraisomer having been found. After hydrolysis and neutralization, the 3-fluorosalicylaldehyde can be recovered by azeotropic distillation along with a substantial quantity of unreacted o-fluorophenol which can be purified for recycle in subsequent preparations.
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