Reaction with isopropyl acetate

C-Alkylation of weakly activated methylpyridines to yield the isopropyl and tert-butyl derivatives (35-40%), which normally requires the use of strong bases, such alkyl lithiums, is earned out effectively using a phase-transfer catalyst and aqueous sodium hydroxide on the /V-methylpyridinium salts. The pyridines are regenerated by reaction with sodium acetate or sodium 4-toluenethiolate [134]. 3-Methylpyridine fails to react under these conditions and the synthesis of 2-ethylpyridines by this procedure is also unsuccessful. 

To a 5 L 3-neck round bottom flask was added the crude carbonylbenzyloxy-3-aminopropanal (115 g, 0.555 mol) followed by addition of water (400 mL) and methanol (1600 mL). The reaction mixture was maintained at 25°C throughout the course of the reaction. After the solution became homogeneous. (S)-Valine methyl ester hydrochloride (90.2 g, 0.538 mol) was added in one portion followed by rapid addition of sodium acetate trihydrate (151 g, 1.11 mol) and sodium cycanoborohydride (73.2 g, 1.17 mol). The reaction mixture was allowed to stir at room temperature for 0.5 hour and was concentrated in vacuo. To this solution, saturated aq sodium bicarbonate (400 mL) was added and the mixture was extracted with isopropyl acetate (1 L). The organic layer was washed with water, dried over sodium sulfate, and concentrated to yield 150 g of crude product, which was dissolved in isopropyl acetate (300 mL) and heptane (2400 mL). Dry HCI was bubbled in and an oily solid precipitated out of solution. The liquid was decanted away from and the solid was dissolved in dichloromethane (3 L). The solution was washed with water (600 mL) and saturated aq sodium bicarbonate (600 mL) and dried over sodium sulfate. It was concentrated in vacuo to yield 105 g (59%) of N-(N-(benzyloxycarbonyl-3-amino)-propyl)valine methyl ester as a light yellow oil. 

With isopropyl acetate, the method of agitation had an influence on conversion. The reaction stalled in shaken pressure bottles, whereas magnetic stirring in glass and mechanical stirring in stainless steel reactors led to efficient... 

Alkylation of diisopropyl (7 )-malate with benzyl bromide produces a 10 1 mixture of benzylated product 945 in 80—85% yield. Use of the isopropyl ester results in higher yields than in the case of the corresponding methyl or ethyl esters, presumably due to reduced ester— enolate condensation. Purification of the diastereomeric mixture is accomplished by hydrolysis to diacid 946 and recrystallization from either chloroform or ethyl acetate/hexane [52% overall yield from diisopropyl (i )-malate]. Treatment of 946 with acetyl chloride and subsequent reaction with isopropyl alcohol gives monoester 948 in 95% overall yield. Amidation of the free acid followed by Hofmann degradation affords 950 in 90% overall yield. Removal of the Boc group and hydrogenation of the benzene ring provides 952. 

This reaction usually works for nonenolizable imines (e.g., A -aryl aldimines) and has the features of readily accessible starting materials, and simple preparation of 3-substituted or unsubstituted 2-azetidinones (i.e., 3-lactams) with direct control of stereoselectivities. It has been reported that the yield of this reaction depends on the activation and the type of zinc. The stereochemistry of /3-lactams depends on the a-substituent of bromoacetates, the solvent, and the alkyl portion of the esters. For example, when the a-substituent is an alkyl group (e.g.. Me, Et, /-Pr, cyclohexyl, r-Bu), the major product has cis geometry, such a trend is especially prevailing for the reaction of acetate with a branched a-substituent (e.g., j-Pr, cyclohexyl, r-Bu) in THF. s For comparison, the reaction of isopropyl acetate in toluene tends to form jS-lactams of trans geometry. In addition, phenyl acetates favor the trans isomers regardless of the solvents. ... 

Perfluorinated p-octaisopropylphthalocyanines having 64 fluorine atoms per Pc unit ([MPcF64], 69) derived from perfluoro-4,5-di(isopropyl)-3,6-diphthalonitrile 61 (see Scheme 16) were prepared and studied in a series of works [51-54], Template cyclotetramerization of the dinitrile 61 proceeds smoothly in a melt with M acetates at 180-200 °C and especially rapidly and effectively under microwave heating (Scheme 19, Table 2). Interestingly, the reaction with ferrous acetate leads to mixture of the Fe" complex [FePcF ] (50.2 %) and the free base [H2PCF64] (22.4 %) [54]. 

LeCalve, S., G. Le Bras, and A. MeUouki (1997c), Kinetic studies of OH reactions with isopropyl, iso-butyl, sec-butyl, and fert-butyl acetate, Int. J. Chem. Kinet., 29, 683-688. 

A solution of 4% aq. H2SO4, (301) was heated to 50"C over 30-60 min. Nitrogen was bubbled through the solution during this time. 4-(Cyano-methyl)phenylhydrazine hydrochloride (1080g, 4.77 mol) was added as a solid to the heated mixture. After it had dissolved, A,A-dimethyl-4,4-dimethoxy-butanamine (965 g, 5.98 mol) was added over a period of 30 min. The mixture was then heated at reflux for 2 h. The reaction mixture was cooled and diluted with portions of 30%o aq. NH4OH (21 total) over 0.5 h at a rate to maintain the temperature at 25-30°C. The product was then extracted into isopropyl acetate (3 x 101). The solution was concentrated to 31 which led to a precipitate which was isolated by filtration and washed with cold isopropyl acetate to give 827.4 g (76%) of product. 

AUyl acetate can be obtained by the vapoi-phase reaction of propylene and acetic acid over a supported Pd catalyst (eq. 20) (110). Reaction of acrylic acid and propylene yields isopropyl acrylate (eq. 21), and catalytic reaction with acetic acid produces isopropyl acetate (eq. 22) (110). 

Esterification is one of the most important reactions of fatty acids (25). Several types of esters are produced including those resulting from reaction with monohydric alcohols, polyhydric alcohols, ethylene or propylene oxide, and acetjiene or vinyl acetate. The principal monohydric alcohols used are methyl, ethyl, propyl, isopropyl, butyl, and isobutyl alcohols (26) (see Esterification Esters, organic). 

Another method for direct precipitation of cellulose acetate powder suitable for extmsion into plastics is described (90). The reaction solution is precipitated with dilute aqueous acetic acid at 80—85°C in the presence of a coagulant such as isopropyl acetate. The resulting powder particles have a higher bulk density and absorb plasticizers more readily than powders obtained by the usual methods. 

The initial reaction between a ketene and an enamine is apparently a 1,2 cycloaddition to form an aminocyclobutanone adduct (58) (68-76a). This reaction probably occurs by way of an ionic zwitterion intermediate (75). The thermal stability of this adduct depends upon the nature of substituents Rj, R2, R3, and R. The enolic forms of 58 can exist only if Rj and/or R4 are hydrogens. If the enamine involved in the reaction is an aldehydic enamine with no 3 hydrogens and the ketene involved is di-substituted (i.e., R, R2, R3, and R4 are not hydrogens), then the cyclo-butanone adduct is thermally stable. For example, the reaction of dimethyl-ketene (61) with N,N-dimethylaminoisobutene (10) in isopropyl acetate... 

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