1487-15-6Relevant articles and documents
Effective, selective hydroalkoxylation/cyclization of alkynyl and allenyl alcohols mediated by lanthanide catalysts
Yu, Xianghua,Seo, SungYong,Marks, Tobin J.
, p. 7244 - 7245 (2007)
Catalytic hydroalkoxylation/cyclization reactions of alkynyl and allenyl alcohols are efficiently mediated by homoleptic lanthanide amides Ln[N(SiMe3)2]3 (Ln = La, Nd, Sm, Y, and Lu). Conversions are found to be highly selective with products distinctly different from those produced by conventional transition metal catalysts. Turnover frequencies as high as 18.0 h-1 at 60 °C are observed. Kinetic studies indicate that these transformations are zero-order in [substrate] and first-order in [catalyst]. Catalytic cycles are proposed in which insertion of C-C unsaturation into a Ln-O bond is turnover-limiting. Copyright
REACTION OF 2-METHYL-4,5-DIHYDROFURAN WITH HYDROGEN CHLORIDE
Polivin, Yu. N.,Karakhanov, R. A.,Sheveleva, T. S.,Ugrak, B. I.,Kelarev, V. I.
, p. 1716 - 1718 (1992)
Reaction of 2-methyl-4,5-dihydrofuran with HCl at 0 deg C yields 5'-chloro-2'-pentanone (13percent) and 1'-(2-methyltetrahydrofuryl-2)-5'-chloro-2'-pentanone (27percent) and at 200 deg 5'-chloro-2'-pentanone exclusively. Keywords: 2-methyl-4,5-dihydrofuran, 5'-chloro-2'-pentanone, 1'-(2-methyltetrahydrofuryl-2)-5'-chloro-2'-pentanone.
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Nefedov et al.
, (1978)
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S-Block cooperative catalysis: Alkali metal magnesiate-catalysed cyclisation of alkynols
Fairley, Michael,Davin, Laia,Hernán-Gómez, Alberto,García-álvarez, Joaquín,O'Hara, Charles T.,Hevia, Eva
, p. 5821 - 5831 (2019/06/18)
Mixed s-block metal organometallic reagents have been successfully utilised in the catalytic intramolecular hydroalkoxylation of alkynols. This success has been attributed to the unique manner in which these reagents can overcome the challenges of the reaction: namely OH activation and coordination to and then addition across a CC bond. In order to optimise the reaction conditions and to garner vital catalytic system requirements, a series of alkali metal magnesiates were enlisted for the catalytic intramolecular hydroalkoxylation of 4-pentynol. In a prelude to the main investigation, the homometallic magnesium dialkyl reagent MgR2 (where R = CH2SiMe3) was utilised. This reagent was unsuccessful in cyclising the alcohol into 2-methylenetetrahydrofuran 2a or 5-methyl-2,3-dihydrofuran 2b, even in the presence of multidentate Lewis donor molecules such as N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA). Alkali metal magnesiates MIMgR3 (when MI = Li, Na or K) performed the cyclisation unsatisfactorily both in the absence/presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) or PMDETA. When higher-order magnesiates (i.e., MI2MgR4) were employed, in general a marked increase in yield was observed for MI = Na or K; however, the reactions were still sluggish with long reaction times (22-36 h). A major improvement in the catalytic activity of the magnesiates was observed when the crown ether molecule 15-crown-5 was combined with sodium magnesiate Na2MgR4(TMEDA)2 furnishing yields of 87% with 2a:2b ratios of 95:5 after 5 h. Similar high yields of 88% with 2a:2b ratios of 90:10 after 3 h were obtained combining 18-crown-6 with potassium magnesiate K2MgR4(PMDETA)2. Having optimised these systems, substrate scope was examined to probe the range and robustness of 18-crown-6/K2MgR4(PMDETA)2 as a catalyst. A wide series of alkynols, including terminal and internal alkynes which contain a variety of potentially reactive functional groups, were cyclised. In comparison to previously reported monometallic systems, bimetallic 18-crown-6/K2MgR4(PMDETA)2 displays enhanced reactivity towards internal alkynol-cyclisation. Kinetic studies revealed an inhibition effect of substrate on the catalysts via adduct formation and requiring dissociation prior to the rate limiting cyclisation step.
Pharmaceutical intermediate 5-chloro-2-pentanone synthesis method
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Paragraph 0022; 0031; 0040; 0046; 0049; 0058, (2018/10/11)
The invention discloses a pharmaceutical intermediate 5-chloro-2-pentanone synthesis method, which comprises: placing 2-methylfuran in a reaction kettle, introducing nitrogen gas, adding a Cu-Mn-Mo composite oxide, controlling the temperature at 20-30 DEG C, introducing hydrogen, controlling the pressure at 0.25-0.3 MPa, carrying out a reaction for 30-45 min, stopping the reaction, filtering the prepared mixture, collecting the filtrate, and preparing 2-methyl-4,5-dihydrofuran; and mixing the prepared 2-methyl-4,5-dihydrofuran and diethyl ether, adding the mixture to a reaction kettle, controlling the temperature at 70-80 DEG C, adding FeCl3, uniformly stirring, controlling the pressure at 0.05-0.08 Mpa, carrying out microwave treatment for 30-45 min, carrying out a stirring reflux reaction for 2-3 h, adding water after completing the reaction, uniformly mixing, carrying out a stirring reaction for 1-2 h, restoring to a room pressure and a room temperature, collecting the organic layer, and carrying out pressure reducing distillation to prepare 5-chloro-2-pentanone. According to the present invention, the synthesis method has characteristics of simple operation, mild condition, less by-product, high product purity and high product yield.
