Showing papers on "Methyl vinyl ketone published in 1982"

Rates and temperature dependences of the reaction of hydroxyl radical with isoprene, its oxidation products, and selected terpenes.

Abstract: Absolute rate constants determined by using the flash photolysis-resonance fluorescence technique are reported for the reactions of hydroxyl radicals with isoprene, ..cap alpha.., and ..beta..-pinene, methyl vinyl ketone, and methacrolein in the temperature range 297-424 K, and with methylglyoxal at 297 K. These results contribute to a more quantitative understanding of the tropospheric fate of gas-phase biomass-related organics and serve as input to models of the chemistry of the natural troposphere.

Desoxy-nitrozucker. 3. Mitteilung. Synthese von Ketosen durch Kettenverlängerung von 1-Desoxy-1-nitro-aldosen. Nucleophile Additionen und Solvolyse von Nitroaethern†

Abstract: Synthesis of Ketoses by Chain Elongation of 1-Deoxy-1-nitroaldoses. Nucleophilic Additions and Solvolysis of Nitro Ethers A method for the preparation of chain elongated uloses based upon the base-catalyzed addition of 1-deoxy-1-nitroaldoses to aldehydes and Michael acceptors and subsequent solvolytic replacement of the nitro group by a hydroxy group is described. Thus, addition of 1, 3 and 9 to formaldehyde, followed by solvolysis gave the chain elongated ulose derivatives 2, 8 and 10 (63–76%), respectively. The configuration at the anomeric center of the addition products was deduced from 13C–NMR. spectra and mutarotation. In the case of 3, the primary addition products 4 and 6 were isolated and acetylated to 5 and 7. The nitro derivatives 4–7 do not follow Hudson's rule of isorotation. Addition of 1 to benzaldehyde (44%) and to nonanal (74%) preceded with a small degree of diastereoselectivity to give 15a/15b, and 11/12, respectively. The configuration of the secondary hydroxyl group of 12 was determined by correlation with methyl 2-hydroxydecanoate (14). Addition of 1 to the galacroaldehyde16 gave a single compound 17 (78%). The structure of this dodecosulose was determined by X-ray crystallography. Solvolysis of the acetylation product 18 in formamide gave the hemiacetal 19 (69%). Michael addition of 1 to acrylonitrile, methyl vinyl ketone and cyclohexenone under solvolytic conditions gave the hemiacetals 27, 30 and 31a,b (49%, 71% and 76%, respectively). Under non-solvolytic conditions (Bu4NF), 1 reacted with acrylonitrile, and crotononitrile to give the anomeric nitro ethers 23 and 24 (67%) and 25 and 26 (84%). respectively. Similarly. 3 added to acrylonitrile to give 28 and 29 (55%, 4:1). This reaction appears to proceed under kinetic control. Addition of 1 to ethyl propiolate and solvolysis yielded the unsaturated spirolactone 32 (50%) and the hemiacetal 33 (17%). Hydrogenation of 32 gave the saturated spirolactone 34 (100%) which was also obtained from 1 and methyl acrylate (63%). Addition of 1 to dimethylmaleate gave the unsaturated ester 35 (48%).

Preparation of New Nitrogen-Bridged Heterocycles. 5. Smooth Michael Additions of 2(3H)-Indolizinone Derivatives

Abstract: Michael additions of some 2(3H)-indolizinone derivatives to α,β-unsaturated nitriles, esters, and an amide gave the corresponding double Michael adducts, 3,3-disubstituted 2(3H)-indolizinones, in moderate to high yields, and those to methyl vinyl ketone afforded further condensed products, spiro[cyclohexane-1,3′(2′H)-indolizin]-2′-ones, instead of the expected 1:2 adducts. On the other hand, the reactions of the indolizinones with activated ethylenes having an appropriate leaving group at the β-position or with an acetylenic ester formed unstable 1:1 Michael adducts, which were converted to stable 2-acyloxy- or 2-alkoxy-3-vinylindolizine derivatives by the treatment with some acylating or alkylating agents in comparatively good yields.

Anionic Copolymerizations of Acrolein with Methyl Vinyl Ketone and Acrylamide by Imidazole

Abstract: The anionic copolymerizations of acrolein (AL) with methyl vinyl ketone (MVK) and acrylamide (AAm) in the presence of imidazole (Im) as an initiator have been studied in tetrahydrofuran at 0°C. The AL-MVK copolymers were found to be composed of vinyl polymer with one Im group attached and having an aldehyde and a carbonyl side chain. The monomer reactivity ratio was determined from a Fineman-Ross plot as r1 = 2.02 and r2 = 0.06. On the other hand, the AL-AAm copolymer were found to be composed of polymer units of 1,2 and 1,4 addition polymerization of AAm. These observations might be explained by the intermolecular hydrogen transfer mechanism of AAm. The polymerization mechanisms were discussed on the basis of these copolymerization results.

Carbon-phosphorus heterocycles. reactions of the enamine 1-(1,2,3,6-tetrahydro-1-phenyl-4-phosphorinyl) pyrrolidine p-sulfide with activated alkenes and acid anhydrides

Abstract: The enamine of 1-phenyl-4-phosphorinanone 1-sulfide has been prepared for the first time from the ketone and pyrrolidine in benzene. Crude enamine could be cyanoethylated at carbon. Hydrolysis of the product followed by treatment of the nitrile with aqueous KOH gave the corresponding carboxylic acid. Reduction of this keto acid with NaBH4 in alkaline medium gave the expected carbinol which lactonized spontaneously. Independent synthesis of the keto acid was achieved by adding methyl acrylate to the crude enamine followed by hydrolysis. The crude enamine also reacted with methyl vinyl ketone in dry benzene. Surprisingly, the product was a bicyclic unsaturated ketone which apparently formed via an aldol type condensation (intramolecular) during the hydrolysis of the enamine reaction mixture (hydrolysis was effected with H2O/CH3CO2H/NaO2CCH3). Interestingly, the crude enamine did not react with mesityl oxide or 1-acetyl-1-cyclohexene as only starting material and a polymeric substance could be obtai...

Processes for making 3-methylthiophene-2-carboxaldehyde and intermediates therefor

Abstract: Processes for preparing isomerically pure 3-methylthiophene-2-carboxaldehyde, an intermediate for synthesis of anthelmintic agents, by reaction of mercaptoacetaldehyde or the dimer, or a polymer thereof, or a dialkylacetal thereof in the presence of a base with (1) methyl vinyl ketone or an alpha- or beta-oxidized derivative of methyl vinyl ketone to form a 3-oxobutylmercaptoacetaldehyde or dialkyl acetal thereof, or an alpha- or beta-substituted derivative thereof which is then converted to 3-methylthiophene-2-carboxaldehyde via appropriate steps including, if necessary, treatment with acid, followed, if necessary, by enamine catalyzed cyclization and, in the case of using methyl vinyl ketone as reactant, a dehydrogenation step; or (2) 3-butyn-2-one to produce a mixture of isomeric 3-oxobut-1-enylmercaptoacetaldehyde or dialkyl acetals thereof which is cyclized to 3-methylthiophene-2-carboxaldehyde. A further aspect of this invention is an improved process for making dialkyl acetals of 2-mercaptoacetaldehyde which comprises reacting an alkyl vinyl ether with sulfur chloride to produce a bis(2-chloro-2-alkoxy ethyl)disulfide which is then treated with an alcohol to afford a bis(2,2-dialkoxyethyl)disulfide which is reduced under alkaline conditions to 2-mercaptoethyl acetaldehyde alkali metal salt which can be alkylated to a thioether, a valuable intermediate.

Thermally induced crossed aldol condensations

Abstract: A relatively efficient, noncatalytic method for effecting crossed aldol condensations between cyclic ketones and aldehydes and between cyclic 1,3-diones and methyl vinyl ketone is reported.