Dimethylacetal

Isobutyric acid, dimethylacetic acid, 2-methylpropanoic acid, (CHjjjCH COOH, colourless syrupy liquid with an unpleasant odour b.p. 154°C. Prepared by oxidation of 2-methylpropanol with K2Cr207 and H2SO4. Salts soluble in water. Used in alkaline solution for sweetening gasoline. 

The allylic geminal diacetate 141 undergoes the monoallylation of malonates to give 142 and the two regioisomers 143 and 144[93,94]. The dimethylacetal 145 or ortho esters of aromatic and a,/3-unsaturated carbonyl compounds react with trimethylsilyl cyanide to give the methyl ether of cyanohydrin[95]. 

Treatment of (89) with lead tetraacetate generates the unstable open-ring aldehyde (90) which is quickly converted to a dimethylacetal (91). Following basic hydrolysis of the methyl ester and acetates, the acetal is cleaved with aqueous acid to produce TxB2. A number of other approaches, including one starting from the Corey aldehyde, have been described (58). 

A cost-efficient synthesis of foHc acid via Schiff base formation is feasible only if 6-formylpterin (23) is readily available. This compound is prepared by the reaction of 2-bromomalondialdehyde dimethylacetal [59453-00-8] (25) with trianainopyrimidinone (10), followed by acetylation and cleavage of the acetal to give compound (23) in 51% overall yield (38). 

Cinnamaldehyde dimethylacetal is prepared by the method used to prepare the corresponding diethylacetal. A mixture of 66.0 g. (0.5 mole) of Aldrich Chemical Company, Inc.), 100 g. (1.06 mole) of trimethyl orthoformate (Eastman Organic Chemicals), 450 ml. of anhydrous methanol (J. T. Baker Chemical Company), and 0.5 g. ofp-toluenesulfonic acid monohydrate (Fisher Scientific Company) is stirred at room temperature for 24 hours. At the end of this time the alcohol is removed with a rotary evaporator and the residue is distilled to give 81-83 g. (91-93%) of cinnamaldehyde dimethylacetal, b.p. 93—96° (0.2 mm.). 

Carbocations can also be generated during the electrolysis, and they give rise to alcohols and alkenes. The carbocations are presumably formed by an oxidation of the radical at the electrode before it reacts or diffuses into solution. For example, an investigation of the electrolysis of phenylacetic acid in methanol has led to the identification of benzyl methyl ether (30%), toluene (1%), benzaldehyde dimethylacetal (1%), methyl phenylacetate (6%), and benzyl alcohol (5%), in addition to the coupling product bibenzyl (26%). ... 

Chemical Designation - Synonyms Dimethylacetic acid Isopropylformic acid 2-Methylpropanoic acid alpha-Methylpropionic acid Propane-2-carboxylic acid Chemical Formula (CH3)2CHCOOH. Observable Characteristics(asshipped) Liquid Color Colorless Odor Unpleasant, acrid. 

Aniline 77 was converted into its diazonium salt with nitrous acid and this was followed by reduction with stannous chloride to afford the corresponding arylhydrazine 78. Condensation of 78 with 3-cyanopropanal dimethylacetal 79 gave the arylhydrazone 80. Treatment of 80 with PPE resulted in cyclization to indole 81. The nitrile group was then reduced to the primary amine by catalytic hydrogenation. Reaction of the amine with excess formalin and sodium borohydride resulted in Imitrex (82). 

Reaction of 2-pyridineacetamides 204 with DMF dimethylacetal afforded 3//-pyrido[l,2-c]pyrimidin-3-ones 205 (98MIP11, 00USP6147080). 

Villsmeier reaction on the dimethylacetal of methoxyacetaldehyde (141) with phosgene and dimethyIformamide affords the acrolein derivative, 142. Condensation of this with guanidine gives the pyrimidine, 143. (The enamine can be viewed as a latent aldehyde-the dimethylamino group is probably lost in the course of an addition elimination reaction with one of the guanidine groups.) This pyrimidine serves as starting material for sulfameter (111). ... 

In geuer il, the acid-cat ilyzed Nef reacdou is carried out in water or water-coutaining solvents. If the teacdou is carried out in methanol, nitre compounds are coaverted into the correspoadmg dimethylacetals. This process has merits over the coaveadoaa] oae due to the wider applicability of the Nef reacdoa fEq. 6.2). ... 

Sometimes ihe intermediate imine is isolated, but generally it is nol and may even be inferior to direct alkylation (5following sequence for it was desired to acetylate ihe alkylated product as formed, A solution of 50 mmol of an aromatic aldehyde (I) and 50 mmol of aminoaceialdehyde dimethylacetal (2), refluxed 1.5 h in toluene under nitrogen, gave after distillation nearly quantitative yields of the SchifTs base 3 (5d). 

C) Preparation of 2-Methyl-3-(2,2,2-Trifluoroethyl)Thiomethyl-6-Chloro-7-Sulfamyl-3,4-Dihydro-1,2,4-Benzothiadiazine-1,1-Dioxide To 4.6 g (0.015 mol) of 4-amino-2-chloro-5-(methylsulfamyl)benzenesulfonamide in 30 ml of the dimethyl ether of ethylene glycol is added 4.08 g (0.02 mol) of 2,2,2-trifluoroethylmercaptoacetaldehyde dimethylacetal followed by 1 ml of ethyl acetate saturated with hydrogen chloride gas. The resulting solution is refluxed for 1.5 hours, cooled and then slowly added to cold water dropwise with stirring. The crude product is filtered, dried and recrystallized from isopropanol (3.2 g), MP 202° to 202.5°C. A second recrystallization from isopropanol raised the MP to 202°... 

Diphenyl-4/7-thiopyran (9) was prepared by application of the known two-step procedure involving the 2,6-dichloro intermediate from the corresponding bis-dimethylacetal (82CJC574). 

A mixture of TMSOTf (0.1 mmol, lmol%), allyltrimethylsilane (11.5 mmol) and dichioromethane (1 ml) was cooled to -78 °C, and to this was added benzaldehyde dimethylacetal (10.5 mmol) in dichioromethane (4ml). The resulting mixture was stirred for 6h at —78°C, and then poured into saturated sodium hydrogen carbonate solution (10 ml) and extracted with ether (3 x 20 ml). The combined organic extracts were washed with brine, dried and concentrated. Chromatography on silica gel (1 20 ether hexane) gave 4-pheny]-4-methoxybut-l-ene (9.2mmol, 88%). 

Nor-codeinon-dimethylacetal3 2,59 g (7,3 mMol) N-Cyan-nor-codeinon-dimethylacetal werden in 150 m/ abs. THF gclost und unter trockenem Stickstoff zu einer Suspension von 1,5 g (40 mMol) Lithiumalanat in 150 ml THF getropft. Man erhitzt 3 Stdn. unter RiickfluB, laBt 12 Stdn. bei 20° stehen, versetzt mit 20 ml Essig-saure-athylester, danach mit 35 ml ges. Kalium-natrium-tartrat-Losung, dampft die organ. Phase i. Vak. ein und kristallisiert den Riickstand aus Ather/Petrolather Ausbeute 1,81 g(75% d.Th.) F 117-118"(aus Ather/Petrolather). 

Cyclohexanon-dimethylacetal — Meihyl-cyclohexyl-alher 74% d.Th. Kp754 122°... 

A related pyranopyrimidine 63 has been prepared by the irradiation of 1,3-dimethylbarbituric acid 61, a methylene active nitrile 47a and N,N-di-methylformamide dimethylacetal 45 [77]. After initial formation of the enam-... 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

---