Dimethoxy propane

The reaction of sucrose with a combination of 2,2-dimethoxy-propane-N,N-dimethylformamide-p-toluenesulfonic acid has been exploited to give various, interesting, cyclic acetal derivatives.32,83-85 This combination of reagents for acetonation is known to give strained, and otherwise inaccessible, acetals of monosaccharides.86-89 Treatment of sucrose with 2,2-dimethoxypropane in N,N-dimethyl-formamide in the presence of a catalytic proportion of p-toluenesul-fonic acid for 80 min at room temperature afforded a mixture containing 4,6-O-isopropylidenesucrose, 2,1 4,6-di-O-isopropyli-... 

A reactor was charged with 2,2-dimethoxy-propane-l,3-diol (0.139 mol), trimethylorthoformate (0.278 mol), p-toluenesulfonic acid (100 mg), and 300 ml of methanol and then stirred for 12 hours. The mixture was then treated with Na2C03 (300 mg) and stirred for an additional 12 hours and then filtered and concentrated. The solid was recrystallized in diethyl ether and 17.5 g of product isolated. 

The step 1 reagent, 2,2-dimethoxy-propane-l,3-diol, was previously prepared by Ferroni et al. (1) and is described. 

Y. Ueno, K. Hori, R. Yamauchi, M. Kiso, A. Hasegawa, and K. Kato, Reaction of maltose with 2,2-dlmethoxypropane, Carbokydr. Res. 69 271 (1981) Y. Ueno, K. Hori, R. Yamauchi, M. Koso, A. Hasegawa, and K. Kato, Reaction of some D-glucobioses with 2,2-dimethoxy-propane, Carbokydr. Res. 96 65 (1981). 

Protection of aldehydes and ketones.1 Bis-o-nitrobenzyl acetals or ketals are removable in 85-95% yield on irradiation at 350 nm in benzene. The acetals or ketals are easily prepared from 1 by an exchange reaction using 2,2-dimethoxy-propane (1, 268-269) catalyzed by an arenesulfonic acid. In the case of hindered ketones (17-keto steroids), the glycol o-N02C6H4CH(OH)CH2OH (2) can be used. 

Shin and Godber (228) used a silica column and a mobile phase composed mainly of isooctane and small amounts of ethyl acetate, acetic acid, and 2,2-dimethoxypropane. The acetic acid component reduced retention times of the late-eluting E vitamers, presumably by competing with water and polar material for binding to silanol groups on the silica surface. 2,2-Dimethoxy-propane reacts with water to form acetone and methanol, and its inclusion stabilized retention times and reduced the need for column regeneration. Chromatograms of vitamin E vitamers in a standard solution and in a saponified rice bran sample are shown in Fig. 13. 

Dimethoxy propane. PTSA. acetone. 75 starting from 3. 

The open-chain derivative (115) of lactose prepared by the action of dimethoxy-propane [128-130] has also been used to prepare the lactose derivative (116) containing a free 2 -hydroxyl group [131]. 

Dimethoxy propane Methyl isopropenyl ether + methanol... 

Dimethoxythietane, obtained by treatment of l,3-dibromo-2,2-dimethoxy-propane with sodium sulfide, is hydrolyzed quantitatively by mineral acid to... 

Hints What is the typical use of 2,2-dimethoxy-propane (26) What is the function of the trimethylaluminum in the second reaction Have you ever met the "NMe(OMe)" motif in another context Do you know the name of this particular amide What is the reason for using exactly 1.0 eq. of the Grignard reagent ... 

Acetonide formation. An acidic resin was used to advantage for the conversion of orotidine methyl ester (I) into the acetonide (2). A small amount of 2,2-dimethoxy-propane was added as water scavenger to a suspension of the ester and the resin in acetone and the mixture was shaken at room temperature for 3 hrs. 

Nucleosides, protection or primary OH Di-p-anisylphenylmethyl chloride. 2,2-Dimethoxy-propane. 

Isopropenyl acetate is converted into the dimethylketal of acetone (2,2-dimethoxy-propane) by treatment with mercuric acetate and boron trifluoride etherate.2 Elimination of the elements of methanol by reaction with acetic anhydride and pyridine give isopropenyl methyl ether. 

Ausnahmen sind die Synthesen des 4-Diisopropylamino-2,3-dimethyl-1 -phenyl-5-py-razolon aus Aceton und 4-Amino-2,3-dimethyl-l-phenyl-5-pyrazolon14 und die von N,N-Dialkyl-anilinen durch reduktive Aminierung von Alkanonen in Form ihrer Acetale mit Anilinen13 (vgl. S. 452). So erhalt man z.B. N,N-Diisopropyl-anilin aus 2,2-Dimethoxy-propan und Anilin iiber Palladium/Kohle (5%) (120 bar/50°) zu 56% d.Th. Mit zunehmender Kettenlange der Acetale sind die Reaktionsbedingungen auf 135-155° und 100 bar zu steigern15. 

Incorporation of both the hydroxyls of 45a into an acetonide nicely protects both functionalities, and the protection is easily removed under mild acidic conditions. This strategy is accomplished by treating 45a with acetone and PTSA (73% yield) [22], 2,2-dimethoxy-propane and PPTS (93% yield) [55], or 2-methoxypropene and PPTS (70-82% yield) [44] to give the desired acetonide 141. 

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