Dimethyl acrolein

Conjugated unsaturated aldehydes (e.g., cltral, g,g-dimethyl-acrolein ). ... 

Note The name "guaiol is also applied to 1,2-dimethyl -acrolein, isolated from guaiacum resin-... 

As early as 1937 Kuhn and Morris (1937) reported the first total synthesis of a retinoid. By Knoevenagel condensation of P-C,5 aldehyde (4) with dimethyl-acrolein (5) and reduction of the product with aluminum isopropoxide, they... 

Donor substituents on the vinyl group further enhance reactivity towards electrophilic dienophiles. Equations 8.6 and 8.7 illustrate the use of such functionalized vinylpyrroles in indole synthesis[2,3]. In both of these examples, the use of acetyleneic dienophiles leads to fully aromatic products. Evidently this must occur as the result of oxidation by atmospheric oxygen. With vinylpyrrole 8.6A, adducts were also isolated from dienophiles such as methyl acrylate, dimethyl maleate, dimethyl fumarate, acrolein, acrylonitrile, maleic anhydride, W-methylmaleimide and naphthoquinone. These tetrahydroindole adducts could be aromatized with DDQ, although the overall yields were modest[3]. 

Other methods for the preparation of cyclohexanecarboxaldehyde include the catalytic hydrogenation of 3-cyclohexene-1-carboxaldehyde, available from the Diels-Alder reaction of butadiene and acrolein, the reduction of cyclohexanecarbonyl chloride by lithium tri-tcrt-butoxy-aluminum hydride,the reduction of iV,A -dimethylcyclohexane-carboxamide with lithium diethoxyaluminum hydride, and the oxidation of the methane-sulfonate of cyclohexylmethanol with dimethyl sulfoxide. The hydrolysis, with simultaneous decarboxylation and rearrangement, of glycidic esters derived from cyclohexanone gives cyclohexanecarboxaldehyde. 

Dihydropyrans have been produced by the 1,3 cycloaddition of methyl vinyl ketone (77) or acrolein (29-J7) with enamines (see Section II.A.2). S-Lactones have been formed as a side product in the reaction of dimethyl ketene with enamines (77), and as the primary products in the reaction of excess ketene with enamines derived from ketones (75) (see Section II.A.4). 

Read ions of Heterocyclic Enamines with a,p-Unsaturated Compounds Enamines react readily with compounds containing a double bone activated by electronegative groups. Addition of acrolein to 1-methyl-2 ethylidenepyrrolidine, followed by dehydrogenation, leads to 1,7-dimethyl indole (133) (Scheme 9) (215). 

V,7V-dimethylaminopyridme provides l-(2-methoxycarbonyl)ethoxy- (40,69%) and l-(2-methoxycarbonyl-l-methyl)ethoxytryptamine (41, 72%), respectively (Scheme 4). The conjugate addition to mesityl oxide proceeds successfully as well, giving iVb-acetyl-1-(1, l-dimethyl-3-oxo)butoxytryptamine (42,49%), while the reaction with methyl 3-methylcrotonate affords 43 in a miserable yield (1.6%). Addition to acrolein results in failure, and 44 is not yet obtained. 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

In a similar manner, 2,2,4-trimethyl-27/,677-pyrimido[2,T4][l,3]thiazines with 7-formyl, 7-acetyl, or 7-C02Me substituents were obtained in good to excellent yields by reacting Ar,Ar-dimethyl-Ar -(4,6,6-trimethyl-6//-l,3-thia-zin-2-yl)formamidine with acrolein, methyl vinyl ketone, or methyl acrylate, respectively <2002S403>. 

The P-alkoxy elimination pathway is important during the incorporation of oxygen-containing monomers. Therefore, it is often necessary to provide distance between the olefin and the polar group, or to prevent chain walking close to the group that can be eliminated by the placement of a quaternary carbon spacer [87], The incorporation of acrolein dimethyl acetal is accompanied by reduced activity and full catalyst... 

Whereas for the hexamethyl compound 150 only products formed by the linear route have been detected with a sizeable number of dienophiles (X=X inter alia TCNE, maleic anhydride, benzoquinone, 1,4-naphthoquinone, acrolein, methyl acrylate102), the parent system 4 undergoes threefold Diels-Alder addition in a star-shaped manner leading to 164 with dimethyl acetylenedicarboxylate and to 165 with fumaroyl chloride followed by methanolysis (equation 20)92. 

Aconitic acid, p206 Acrolein, p203 Acrolein diethyl acetal, d312 Acrolein dimethyl acetal, d521 Acrylaldehyde, p203... 

The analogous two-phase reaction of acrolein with thiolacetic acid under basic conditions in the presence of tetra-n-butylammonium iodide initially forms the Michael adduct which, upon hydrolysis, reacts further to produce l-formyl-5-thia-cyclohexene (see Scheme 4.17). In a similar manner, crotonaldehyde produces 1 -formyl-4,6-dimethyl-5-thiacyclohexene [13]. 

The unsaturated aldehyde (0.1 mol) is added to a two-phase system of thiolacetic acid (7.6, 0.1 mol) in aqueous NaOH (50%, 16 ml) and TBA-I (0.1 g, 0.27 mmol) in CH2CI2 (100 ml) over a period of ca. 30 min at 0°C. The mixture is stirred for 2.5 h at 0°C and then heated under reflux for 20 min. The organic phase is separated, diluted with Et20 (50 ml), washed with H20 (3 x 25 ml), and dried (MgS04). Evaporation of the solvent gives i-formyl-5-thiacyclohex-l-ene (41%) from acrolein and 1-formyl-4,6-dimethyl-5-thiacyclo-hex-l-ene (81%) from crotonaldehyde. 

Ethyl diazoacetate (22.8 g, 0.20 mol) is added at a rate of 1.5 mL h" to a stirred mixture of acrolein dimethyl acetal (40.8 g, 0,40 mol) and rhodium(Il) acetate (0.44 g, 0.001 mol, 0.5%), keeping the temperature of the reaction mixture at 20 °C. The mixture is then filtered through a short column of neutral alumina which is washed with ether. Distillation of the combined filtrates yields 19.2 g of a fraction (bp 107-112 °C, 13 Torr) consisting of 93% of the title compound (47% yield) and 7% of the cyclopropanation product. 

Starting material for the synthesis is the enaminoaldehyde obtainable by some version of the Villsmeyer reaction on pi coline derivative 9. Condensation of that with cyanoacetamide in the presence of methoxide leads to pyridone J. The reaction can be rationalized by assuming that the initial step consists in Michael addition of the anion from acetamide to the acrolein elimination of dimethyl amine would afford the intermediate Conden-... 

Another approach to obtain pure enantiomers of isoxazolines involves the use of chiral acrolein aminals, formed with A.A -substituted diaminodiphenylethanes (194). Thus, with this chiral imidazolidinyl auxiliary in the p-position, and with unsaturated esters serving as the dipolarophile, benzonitrile oxide afforded only one regioisomeric cycloadduct with good stereoselectivity (194) (Scheme 6.40). When the analogous A,A -dimethyl auxiliary was chosen, excellent stereoselectivity was accompanied by poor regioselectivity (194). 

Conversion of the Adduct from Bromine and Acrolein into the Dimethyl and Diethyl Acetal... 

Several graft copolymerizations were described by Ballantine (17, 64), Henglein (104, 105) and coworkers. Different monomer-polymer systems were examined styrene on polymethyl methacrylate, poly-2, 5-dichlorostyrene, polytetrafluoroethylene, polyethylene, polypropylene and polyisobutylene, acrylonitrile on polyethylene, rubber, polymethyl methacrylate and dimethyl polysiloxane, vinylpyrrolidone and acroleine on polymethyl methacrylate. The results agree with the preceding ones moreover they show the influence of the swelling and diffusion of the monomer into the polymer. 

A very useful three-carbon olefin is acrolein dimethyl acetal (5). Acrolein itself cannot be used because it polymerizes and/or reacts with amines under the normal reaction conditions. With piperidine or morpholine as the base, acrolein acetals react in good yield with a wide variety of vinylic bromides to give dienal acetals and/or ami-noenal acetals. These product mixtures, after being treated with excess aqueous oxalic acid and being steam distilled, yield E,E-conjugated dienals, usually in good yields. Methacrolein acetals and 3-buten-2-one ethylene ketal also react well, but the crotonaldehyde acetals do not. 

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