- Synthetic method and process of halogenated cyclopropane
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The invention discloses a synthetic method and process of halogenated cyclopropane. The synthesis method and process comprise the following two steps of: (1) reacting cyclopropylamine serving as a rawmaterial with halogenated metal salt in the presence of nitrosation reagents such as nitrous acid ester to obtain 1, 1-dihalogenated cyclopropane; and (2) carrying out metallization reaction on the 1, 1dihalogenated cyclopropane and an organic metal reagent, and hydrolyzing to obtain halogenated cyclopropane. The synthesis method and process have the advantages that toxic reagents causing environmental pollution are not used, the purity and yield of the obtained product are high, and the synthesis method and process are suitable for industrial production.
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Paragraph 0014
(2021/03/31)
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- Novel method for synthesizing cyclopropyl bromide
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The invention discloses a novel method for synthesizing cyclopropyl bromide. The method comprises the following steps: by taking bromoethylene as a raw material, carrying out denitrification cyclization reaction on the bromoethylene and diazomethane in a solvent under the action of a Pd(oAc)2 catalyst to obtain a cyclopropyl bromide crude product, and carrying out acid pickling, filtering layering and normal-pressure rectification to obtain a pure product with the content of 99% or more and the yield of 80% or more. The synthesis method has the advantages of mild conditions, few byproducts, high yield and environmental friendliness, and is more suitable for industrial amplification.
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Paragraph 0003; 0010-0012
(2021/10/11)
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- Novel synthesis method of cyclopropyl bromide
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The invention discloses a novel method for synthesizing cyclopropyl bromide, which comprises the following steps of: carrying out denitrification cyclization reaction on dibromoethylene serving as a raw material and diazomethane in a solvent under the action of a Pd(OAc)2 catalyst, carrying out Grignard reaction and hydrolysis debromination to obtain a cyclopropyl bromide crude product, conducting filtering, and conducting layering and rectifying at normal pressure to obtain a pure product with the content of 99.5 percent or more and the yield of 85 percent or more. The synthesis route has the advantages of few byproducts, mild reaction conditions, high yield and environmental friendliness, and has a better industrial prospect.
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Paragraph 0008-0013
(2021/09/21)
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- Novel method for synthesizing cyclopropyl bromide
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The invention discloses a novel synthetic method for synthesizing cyclopropyl bromide. A decarboxylation bromination reaction is carried out in a solvent by taking cyclopropanecarboxylic acid as a rawmaterial, lead tetraacetate as a catalyst and metal bromide such as lithium bromide as a bromination reagent to obtain crude cyclopropyl bromide, reduced pressure distillation is carried out on the crude cyclopropyl bromide to obtain a pure product with the content of 99% or above and the yield of 85% or above, the obtained byproduct lead bromide is reacted with ammonium acetate, and the reactionproduct is oxidized to obtain lead tetraacetate for recycling. The synthesis route has the advantages of accessible raw materials, mild conditions, fewer byproducts, high yield and environment friendliness, and is suitable for industrial amplification.
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Paragraph 0013-0018
(2020/05/14)
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- Decarboxylative Bromination of Sterically Hindered Carboxylic Acids with Hypervalent Iodine(III) Reagents
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Sterically hindered three-dimensional (3D) alkyl halides are promising precursors for various reactions; however, they are difficult to synthesize via conventional reactions. We present an efficient and practical method for decarboxylative bromination of sterically hindered 3D aliphatic carboxylic acids using commercially available (diacetoxyiodo)benzene and potassium bromide, one of the most stable and cheapest bromine sources in nature. The present method features a metal-free/Br2-free system, mild reaction conditions, one-pot operation under air at room temperature, wide functional group compatibility, and gram-scale synthetic capability. This highly efficient reaction cleanly converts a broad range of carboxylic acids, the most inexpensive and readily available sources of highly strained/naturally occurring/drug-related scaffolds, into the corresponding alkyl bromides in good to high yields.
- Kanazawa, Junichiro,Koyamada, Kenta,Miyamoto, Kazunori,Uchiyama, Masanobu,Watanabe, Ayumi
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supporting information
p. 1328 - 1334
(2020/08/14)
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- NMR spectroscopy of organolithium compounds, part XXXIII: trans-2,3-dimethylcyclopropyllithium aggregation in diethylether: An equilibrium between three different complexes of comparable energy and the influence of LiBr on aggregate structure
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The aggregate formation of trans-2,3-dimethylcyclopropyllithium (2) was studied in diethylether (DEE). With the help of the isotopic fingerprint method three clusters, a monomer, a dimer, and a fluxional tetramer in the ratio 1.00:0.53:0.22 were identified at 187?K. In the presence of 1 equivalent of LiBr cyclopropyllithium (1) forms in DEE at 163?K a mixed dimer and a mixed tetramer, while in THF a mixed dimer dominates. Under the same conditions 2 and 2,2,3,3-tetramethylcyclopropyllithium (3) form in the solvent mixture DEE/THF (1:1) mixed dimers, as does 2 also in THF.
- Fox, Thomas,Günther, Harald
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- Preparation method of Roxadustat
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The invention discloses a preparation method of Roxadustat. The chemical name of Roxadustat is 2-[[5-bromo-4-(4-cyclopropyl-1-naphthalene)-4H-1,2,4-triazole-3-yl] sulfo] acetic acid. The molecular formula is C17H14BrN3O2S. The preparation process is concise, raw materials are easily available and the preparation process is economical and environmentally friendly, industrialization is achieved favorably, the economical technical development of bulk pharmaceutical chemicals of Roxadustat can be promoted, the production cost is lowered, the yield is high, the environmental pollution is slight, and the method is suitable for large-scaled production.
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Paragraph 0011; 0012; 0013
(2018/04/28)
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- A new method for synthesizing ring-propyl bromide (by machine translation)
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The invention relates to a new method for synthesizing ring-propyl bromide of: the ring n-propyl formate reaction with carbonyl diimidazole generating cyclopropanecarboxylic acyl imidazole, the intermediate is then mixed together with trichloro curafume, maintain 10 °C to 140 °C slowly dropping under the conditions of the free radical bromination reaction of deacidifying cyclopropyl bromine thick obtained after, through simple atmospheric distillation to obtain the purity 99% product of the above. The mild reaction conditions, conventional reagent used is cheap and easy to obtain, by avoiding the use of oxidized mercury squeezing, is suitable for industrial production. (by machine translation)
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Paragraph 0024; 0027; 0028
(2017/01/02)
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- Absolute Rate Constants for Bromine Abstraction from N-Bromoimides and Br2 by Alkyl Radicals
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Imidyl radicals react with cyclopropanes solely via hydrogen abstraction.In the case of methylcyclopropane, the major product (cyclopropylcarbinyl bromide) is derived from abstraction of hydrogen from the methyl group.The resultant cyclopropylcarbinyl radical is partioned between two pathways: (1) abstraction of Br from N-bromoimide and (2) rearrangement to the allylcarbinyl radical (eventually yielding 4-bromo-1-butene).Since the absolute rate of the rearrangement is known, an absolute rate constant for the abstraction of Br from N-bromoimides by alkyl radicals can be derived (CH2Cl2 solvent, 15 deg C), k ca. (1.3-1.6)1xE10 M-1s-1.Reactions carried out in the presence of Br2 provide a third pathway for scavenging of the cyclopropylcarbinyl radical, providing kBr2=2.2x1E10 M-1s-1.Thus, trapping of primary R. by either N-bromoimides or Br2 occurs at rates that are diffusion-controlled.
- Tanko, James M.,Skell, Philip S.,Seshadri, Sri
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p. 3221 - 3225
(2007/10/02)
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- Reaction of gem-Dibromocyclopropanes with Potassium Dimethyl Phosphite in Liquid Ammonia. A Highly Stereoselective Reduction
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Although gem-dibromocyclopropanes undergo subsitution with other SRN1 nucleophiles in liquid ammonia solution stimulated by "350 nm" light, only reduction is observed with dimethyl phosphite ion.This reduction proceeds in the absence of light and involves nonradical intermediates.It gives high yields of the trans monobromides 4 with little or no contamination by the cis isomers 5 or the direduced products 6. gem-Dichlorocyclopropanes are inert under the reaction conditions.The reaction is suited to preparative work.
- Meijs, Gordon F.,Doyle, Ian R.
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p. 3713 - 3716
(2007/10/02)
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- Reactions of Cyclopropyl Sulfonates with Nucleophiles: SN2 Displacements at Cyclopropanes with Inversion
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Treatment of cyclopropyl trifluoromethanesulfonate (3) with tributylhexadecylphosphonium azide (QN3) in aprotic solvents almost quantitatively afforded cyclopropyl azide (6) in a second-order reaction.Nucleophilic displacements with ring preservation were also achieved using QCN or QBr.The analogous reactions of the epimeric 2-methylcyclopropyl trifluoromethanesulfonates (16, 17) with QN3 highly stereospecifically yielded the 2-methylcyclopropyl azides (24, 25) with inversion in addition to the allylic azides 27, 28, and 29.The product fraction of cyclic azides decrea sed with growing steric hindrance in the order 3 > 16 > 17.The experimental results show that SN2 displacements take place with clean inversion at the cyclopropane carbon atom.
- Banert, Klaus
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p. 1564 - 1574
(2007/10/02)
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- Temperature Effects on the Selectivity of ?-Radicals
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Bent ?-radicals 3a-i, generated from alkylmercuric salts 1 and/or peresters 2, were treated with a BrCCl3/CCl4 competition system at different temperatures.Exner-analysis of these selectivity data (table 1) shows, that radicals of sp2 type 3a-d and bridgehead radicals 3e-i follow different isoselective relationships (figure 1, 2).Reversal of the selectivity row occurs at 310 and 210 K, respectively.Above of these isoselective temperatures less shielded radicals are more selective than more shielded radicals because entropy effects overcompensate enthalpy effects (table 2).Comparison with ?-radicals 6 shows, that each type of carbon radicals follows an isoselective relationship by its own.
- Giese, Bernd,Stellmach, Joachim
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p. 3294 - 3302
(2007/10/02)
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