共查询到20条相似文献,搜索用时 15 毫秒
1.
K. Boukallaba A. Elachqar A. El Hallaoui A. Alami S. El Hajji B. Labriti 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):819-823
α-heterocyclic α-aminophosphonates were obtained in good yields by N-of several nitrogen heterocycles with α-azido-α-aminophosphonate 1. 1 相似文献
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3.
Colpaert F Mangelinckx S Rocchetti MT De Kimpe N 《Organic & biomolecular chemistry》2011,9(2):549-558
α-Methoxy- and α-ethoxyketones, as important intermediates in organic synthesis and flavor compounds in food chemistry, were synthesized by deprotonation of N-(1-alkoxy-2-propylidene)isopropylamine, prepared by condensation of the corresponding α-alkoxyacetone with isopropylamine, and subsequent reaction of the corresponding 1-azaallylic anions with alkyl halides to afford α'-alkylated, α-alkylated and α,α'-dialkylated ketimines. Hydrolysis of the imino function led to the desired substituted α-alkoxyketones. The ratio of α-, α'-, and α,α'-(di)alkylated compounds depended on the amount of base used and on the nature of the alkylating reagent. 相似文献
4.
Long Chen Yun-Xiang Zou Xin-Yue Fang Xu Yin 《Phosphorus, sulfur, and silicon and the related elements》2018,193(3):168-177
We report a convenient catalytic Friedel-Crafts arylation of α-aryl α-hydroxyphosphonates with various (hetero)aromatic compounds. HOTf (trifluoromethanesulfonic acid) is identified to be the best Brønsted acid catalyst, and the desired α-diarylmethylphosphonates were obtained in up to 41–95% yield. 相似文献
5.
α-Telluroketones were prepared by reacting 4-methoxyphenyltellurium trichloride either with ketones or silyl enol ethers of ketones. The products upon pirolysis furnish α-chloro ketones. 相似文献
6.
《Tetrahedron: Asymmetry》2001,12(21):3047-3052
A study of the enantioselectivity exhibited by the lipase B from Candida antarctica in the transesterification of different α-substituted α-propylmethanols with vinyl acetate is shown. The best results are obtained when the large-sized (L) substituent of the alcohol is either a phenyl group or more especially a cyclohexyl group, although the reaction rates are lower than when linear or slightly branched groups are present. It is also found that ramification at the β-position of the L substituent has a deleterious effect on both lipase activity and enantioselectivity. Moreover, some α-substituted benzyl alcohols bearing medium-sized (M) substituents larger than an ethyl and smaller than a propyl group are resolved by means of this methodology with moderate-good enantioselectivities (E=46–57) and similar reaction rates. 相似文献
7.
Summary Products of the addition of allyl chloromethyl ether, -chloroethyl methyl ether, -acetoxyethyl chloromethyl ether, cyclohexyl chloromethyl ether, and -chloroethyl ethyl ether to the thiooxides of ethylene and propylene have been prepared. 相似文献
8.
Abstract Vinyl sulfides are useful synthetic intermediates1 which have received increasing attention recently both as masked carbonyl moieties2 and in carbon-carbon bond forming reactions.3 With regard to the latter, vinyl sulfide derivatives which are substituted in the α-position with halogen, tin, selenium, etc., are particularly useful due to the ready formation of anions upon treatment with a variety of organometallic reagents.3 d ? 1 We report here that synthetically useful halovinyl sulfides can be produced in high yield by the eliminative deoxygenation of the corresponding α-halosulfoxides induced by electrophilic silicon reagents. 相似文献
9.
Saverio Florio Filippo M. Perna Renzo Luisi José Barluenga 《Tetrahedron letters》2004,45(43):8027-8030
The synthesis of α-oxazolinylalkanamides 2, based on the reaction of α-chloroalkyloxazolines 1 with hexacarbonyltungsten [W(CO)6] and lithium amides, has been developed. A plausible mechanism involving the ketene 5 as the intermediate is also proposed. 相似文献
10.
N. A. Keiko Yu. A. Chuvashev L. G. Stepanova O. B. Bannikova M. G. Voronkov 《Russian Chemical Bulletin》1996,45(1):180-182
Monomeric -alkylthioacroleins were obtained by the reaction of alkylthioacetaldehydes with formaldehyde and diethylamine hydrochloride. The structures of the -alkylthioacroleins were confirmed by NMR spectroscopy and mass spectrometry as well as by chemical transformations of these compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 188–190, January, 1996. 相似文献
11.
Lapidus A. L. Eliseev O. L. Bondarenko T. N. Sizan O. E. Ostapenko E. G. Beletskaya I. P. 《Kinetics and Catalysis》2004,45(2):234-238
The catalytic carbonylation reactions of -haloketones in the presence of palladium compounds were studied. Chloroketones were selectively converted into -ketoesters, whereas bromoacetophenone was partially reduced to acetophenone. The reaction rate at atmospheric pressure was much lower than that at an elevated pressure. A reaction mechanism was proposed. 相似文献
12.
Summary All possible N-oxides of -benzamidonicotine were prepared and were hydrolyzed with hydrochloric acid to N-oxides of the corresponding -aminonicotines. 相似文献
13.
McLaughlin M Belyk KM Qian G Reamer RA Chen CY 《The Journal of organic chemistry》2012,77(11):5144-5148
A general method for the preparation of α-hydroxyacetophenones is presented. Functionalized arylmagnesium species are transmetalated to the corresponding arylzinc intermediates, which undergo Cu(I)-catalyzed reaction with acetoxyacetyl chloride. Acidic hydrolysis of the acetate group releases the target α-hydroxyacetophenones with minimal production of undesired polymeric degradates that are often observed under alternative conditions. 相似文献
14.
A series of new α-hydroxyphosphonate (5–14) have been synthesized in high yields by reaction of β-chloro-α,β-unsaturated aldehydes (1–4) and trialkyl phosphite in the presence of chlorotrimethylsilane at room temperature under solvent-free conditions. In addition, compounds (5–14) were reacted with acetic anhydride in DBU to give the new α-acetoxyphosphonate derivatives (15–23). All these phosphonates (5–23) were obtained as mixtures of two (E and Z) isomers and fully characterized by multinuclear (1H, 13C, and 31P) NMR, IR spectroscopy and HRMS. 相似文献
15.
Seyed Mohammad Vahdat Robabeh Baharfar Akbar Heydari Samad Khaksar 《Tetrahedron letters》2008,49(46):6501-6504
A new and highly flexible procedure is described for the synthesis of α-amino- and α-hydroxy phosphonates. In the presence of a catalytic amount of oxalic acid (10 mol %), trimethyl phosphite reacts with aldehydes or imines (generated in situ from an aldehyde and an amine) to yield the corresponding coupled products in good yield. 相似文献
16.
《Tetrahedron letters》1988,29(40):5151-5154
A regioselective allylation of α-isocyanoesters at the α-carbon was achieved by the Claisen rearrangement of allylic α-isocyanoesters via the corresponding silyl ketene acetals in situ generated. 相似文献
17.
《Tetrahedron letters》1987,28(48):6019-6020
α-Enaminoketones are readily accessible through reaction of α-bromoketones with sodium azide followed by an elimination of molecular nitrogen. The reaction is base catalyzed and proceeds under relatively mild conditions. An anionic mechanism is proposed. 相似文献
18.
《Tetrahedron: Asymmetry》1999,10(23):4653-4661
This report describes the synthesis of enantiomerically pure (S)- and (R)-α-vinylalanines and (S)- and (R)-α-ethynylalanines, four quaternary α-amino acids, using a straightforward synthetic route and starting from (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals. 相似文献
19.
Sok-Teng Tong 《Tetrahedron》2009,65(25):4801-1088
The direct asymmetric organocatalytic α-oxidation of aldehydes using trans-2-(p-methylphenylsulfonyl)-3-phenyloxaziridine is reported. This method affords the S isomer of α-hydroxy aldehydes, thereby complementing the selectivity for the R isomer observed using the two-step nitrosobenzene method. Use of α-methylproline and α-methylproline tetrazole significantly increases the enantioselectivity observed for the α-oxidation of aldehydes compared to analogous unsubstituted organocatalysts. 相似文献
20.
The diffusion coefficients of nitrogen were measured in polycrystalline h.c.p. α-Zr and α-Hf. The nitrogen-implanted zirconium and hafnium samples used for the measurements were annealed at temperatures of 500–700°C and 550–900°C respectively. The nitrogen profiles were probed using the broadening of the (p, αγ) resonance. Doses of 1.8 × 1020 and 1.2 × 1021 ions m−2 were used for the 40 keV 15N implants, but no differences in the diffusivity were observed. Values of 2.50 eV and 2.51 eV for the activation energy and 0.56 cm2 s−1 and 0.024 cm2 s−1 for the frequency factor were obtained for α-Zr and α-Hf respectively. 相似文献