Showing papers on "Diazomethane published in 2018"
TL;DR: This review aims to highlight the recent developments in processes and equipment concepts for the generation and consumption of diazomethane in continuous mode, and focuses specifically on the continuous processes and Equipment solutions that have enabled the entire sequence consisting of synthesis of the diazometrichane precursor, subsequent generation and purification ofdiazometHane, and the downstream reaction to achieve the target product.
27 citations
TL;DR: Three new pyrazole 3-triflones containing a triflyl group at the 3-position were synthesized by using a previously unknown anionic (difluoromethanesulfonyl)diazomethane species under a similar strategy.
18 citations
TL;DR: In this article, the 1,3-dipolar cycloadditions of diazomethane and diazoethane with methyl 3-(diethylamino)propiolate were investigated experimentally and computationally by employing density functional theory.
17 citations
TL;DR: A Cu(I)-catalyzed cross-coupling reaction of terminal alkynes and bis(trimethylsilyl)diazomethane is reported, which provides an efficient synthetic method for 1,1-disilyl allenes.
Abstract: A Cu(I)-catalyzed cross-coupling reaction of terminal alkynes and bis(trimethylsilyl)diazomethane is reported. Mechanistically, the reaction is based on the recently developed cross-coupling reactions through metal-carbene migratory insertion. This reaction provides an efficient synthetic method for 1,1-disilyl allenes. Subsequent transformations of 1,1-disilyl allenes are investigated, which show diverse reactivities of these allenes.
17 citations
TL;DR: In this paper, a dodecyl diaryl carbene was generated from a strong solar light, which was very convenient to insert into the X H bonds (X = C, N) on the surface of polyurethane films.
15 citations
TL;DR: In depth spectroscopic and crystallographic analyses document interesting structural features of these previously unknown diazo derivatives of Arndt-Eistert chemistry as well as analogous acylation-type processes on secondary arylamino diazoketones.
Abstract: Primary and secondary α-halomethyl diazoketones generated via Arndt–Eistert chemistry with minimum loading of diazomethane efficiently alkylate aromatic amines in the presence of calcium oxide to furnish the corresponding α-arylamino diazoketones under full chemocontrol. Such a simple inorganic acid scavenger fully neutralizes the hydrohalic acid formed during the nucleophilic displacement which otherwise would immediately react to produce the corresponding α-haloketone. The methodology can be further exploited in analogous acylation-type processes on secondary arylamino diazoketones. In depth spectroscopic (1H, 13C, and 15N NMR ) and crystallographic analyses document interesting structural features of these previously unknown diazo derivatives.
9 citations
TL;DR: Formal addition of diazomethane's terminal nitrogen atom to the 9,10-positions of anthracenes yields H2CN2A (1, A = C14H10 or anthracene).
Abstract: Formal addition of diazomethane's terminal nitrogen atom to the 9,10-positions of anthracene yields H2CN2A (1, A = C14H10 or anthracene). The synthesis of this hydrazone is reported from Carpino's hydrazine H2N2A through treatment with paraformaldehyde. Compound 1 has been found to be an easy-to-handle solid that does not exhibit dangerous heat or shock sensitivity. Effective umpolung of the diazomethane unit imbues 1 with electrophilicity at the methylene carbon center. Its reactivity with nucleophiles such as H2CPPh3 and N-heterocyclic carbenes is exploited for CC bond formation with elimination of dinitrogen and anthracene. Similarly, 1 is demonstrated to deliver methylene to a nucleophilic singlet d2 transition metal center, W(ODipp)4 (2), to generate the robust methylidene complex [2CH2]. This behavior is contrasted with that of the Wittig reagent H2CPPh3, a more traditional and Bronsted basic methylene source that upon exposure to 2 contrastingly forms the methylidyne salt [MePPh3][2CH].
7 citations
TL;DR: In this article, the first diazomethane-mediated synthesis of azetidine-embedded tetracyclic ketal systems was reported, where the bridgehead-bromo-substituted hemiaminal acetals gave higher yields compared to the corresponding bridgehead -chloro -substitution.
Abstract: Herein, the first diazomethane-mediated synthesis of azetidine-embedded tetracyclic ketal systems is reported. Reactions of norbornyl hemiaminal acetals with diazomethane afford azetidine-embedded tetracyclic ketals in good to excellent yields. The bridgehead-bromo-substituted hemiaminal acetals give higher yields compared to the corresponding bridgehead-chloro-substituted hemiaminal acetals. The hemiaminal acetals are prepared stereoselectively via nucleophilic addition of various amines to norbornyl α-diketones from the exo face.
5 citations
TL;DR: Methylation with methyl fluorosulfate at the sulfur atom and treatment with a strong base induced an α-hydroxyphosphonate-phosphate rearrangement with formation of dimethyl sulphide and two enantiomerically pure enol phosphates.
Abstract: Racemic ethyl hydrogen (1-hydroxy-2-methylsulfanyl-1-phenylethyl)phosphonate was resolved with (R)-1-phenylethylamine. The (R)-configuration of the (-)-enantiomer was determined by chemical correlation. Esterification of the (-)-enantiomer with a substituted diazomethane derived from 3-hydroxy-1,3,5(10)-estratrien-17-one delivered two epimeric phosphonates separated by HPLC. Methylation with methyl fluorosulfate at the sulfur atom and treatment with a strong base induced an α-hydroxyphosphonate-phosphate rearrangement with formation of dimethyl sulphide and two enantiomerically pure enol phosphates. Their oily nature interfered with a single crystal X-ray structure analysis to determine the stereochemistry at the phosphorus atom.
4 citations
TL;DR: Ferrocenyl thioketones bearing a hetaryl, phenyl or alkyl group as the second substituent react with (trimethylsilyl)diazomethane at ca. −30°C in THF solution without formation of a stable [3 + 2]-...
3 citations
Patent•
27 Feb 2018
TL;DR: In this paper, a method for synthesizing trifluoromethyl cyclopropane in a two-phase system through a one-pot method without carrying out separation is presented.
Abstract: The invention discloses a method for mildly generating perfluoroalkyl diazomethane in situ. By utilizing the method, through starting with perfluoroalkyl aldehyde or a hydrate thereof, which is low inprice and is easily obtained, a substitution reaction is generated with a derivative of benzenesulfonyl hydrazide under the catalysis of protonic acid; the dehydration is carried out in the presenceof a dehydrating agent to obtain a perfluoroalkyl diazomethane precursor; the perfluoroalkyl diazomethane is slowly released in an alkaline condition. Further, by utilizing the preparation method of the perfluoroalkyl diazomethane, a novel method for synthesizing trifluoromethyl cyclopropane in a two-phase system through a one-pot method without carrying out separation is invented. By using the method, the separation of trifluoromethyl diazomethane which has toxicity and explosion danger is avoided; the method has the advantages of mild reaction condition, wide substrate range and good functional-group tolerance, and meanwhile, the method has the advantages of being simple and convenient to operate and needing no special equipment to slowly dropwise add, can be used for safely and efficiently synthesizing the trifluoromethyl cyclopropane, whose order of magnitude is 1 to 100 grams, in a laboratory and has further industrialized application potential.
TL;DR: Dehydrobromination of 2-(1,2-dibromoethyl)-1,3-dioxocyclanes with sodium amide in liquid ammonia provided cyclic acetals of propargyl aldehyde as discussed by the authors.
Abstract: Dehydrobromination of 2-(1,2-dibromoethyl)-1,3-dioxocyclanes with sodium amide in liquid ammonia provided cyclic acetals of propargyl aldehyde. Reactions of the resulting compounds with nitrile oxides and diazomethane afforded the corresponding isoxazole and pyrazole derivatives.
Patent•
27 Apr 2018
TL;DR: In this paper, a novel method for preparing a 3-trifluoromethylisooxazole compound by one-pot was proposed, where trifluoroethylamine which can be purchased in markets is prepared into fluorinated diazomethane, and then the fluorinated mixture and an alkynes compound are in coupled reaction under catalysis of low-price copper.
Abstract: The invention discloses a novel method for preparing a 3-trifluoromethylisooxazole compound by one-pot According to the method, trifluoroethylamine which can be purchased in markets is prepared intofluorinated diazomethane, and then the fluorinated diazomethane and an alkynes compound are in coupled reaction under catalysis of low-price copper The method is simple to operate, reaction conditions are mild, the cost is low, by-products are fewer, the yield is high, tolerance of a functional group is high, and reaction can be amplified Meanwhile, much deeper mechanism study is carried out, and a mechanism that a trifluoromethyl ketoximes compound intermediate may be produced in the reaction is proposed
Patent•
24 May 2018
TL;DR: In this article, an electron withdrawing group (EWG) was introduced on the benzene ring of the benzenesulfonyl hydrazone, and utilizes electronic effects and steric effects to facilitate the departure of the EDG on the BSH, thus producing the diazomethane derivative in very mild conditions.
Abstract: Disclosed is a mild preparation method for a diazomethane derivative. The preparation method for the diazomethane derivative comprises the following steps: benzenesulfonyl chloride having the structure of formula I undergoes a hydrazine reaction with water to produce benzenesulfonyl hydrazide having the structure of formula II; the benzenesulfonyl hydrazide having the structure of formula II is reacted with an aldehyde or a ketone having the structure of formula III to produce benzenesulfonyl hydrazone having the structure of formula IV; the benzenesulfonyl hydrazone having the structure of formula IV is mixed with an alkaline and an organic solvent and then undergoes a metathesis reaction to produce a diazomethane derivative having the structure of formula V, the derivative is not purified by isolation and is further used in a synthesis reaction and insertion reaction of a strained small ring. The present invention introduces an electron withdrawing group (EWG) on the benzene ring of the benzenesulfonyl hydrazone, and utilizes electronic effects and steric effects to facilitate the departure of the benzenesulfonyl on the benzenesulfonyl hydrazone, thus producing the diazomethane derivative in very mild conditions, specifically, at room temperature.
Patent•
29 Oct 2018
TL;DR: In this paper, the preparation of polymeric products containing cyclopropane groups in the composition of macromolecules, of general formula (1):1, having the ratio of links (+b):(c+d)=60-90:10-40, is the interaction of 1,2-polybutadiene with diazomethane in an organic solvent medium in the presence of a catalyst at a molar ratio of 1:3.0:0.0025-0.01.
Abstract: FIELD: chemistry.SUBSTANCE: invention relates to the preparation of polymers containing unsubstituted cyclopropane groups in macromolecules. Process for the preparation of polymeric products containing cyclopropane groups in the composition of macromolecules, of general formula (1):1,having the ratio of links (+b):(c+d)=60–90:10–40, is the interaction of 1,2-polybutadiene with diazomethane in an organic solvent medium in the presence of a catalyst at a molar ratio of 1,2-polybutadiene : diazomethane : a catalyst of 1:3.0:0.0025–0.01. Process is characterized in that the preparation of diazomethane and its interaction with 1,2-polybutadiene are carried out in one reaction volume (in situ).EFFECT: simplifying the technology while preserving the possibility of purposefully modifying the initial polymer in a wide range of molecular weights by cyclopropane groups.3 cl, 1 tbl, 8 ex