Esters aldehyde diacetates

It may be prepared synthetically by reducing cinnamic aldehyde diacetate, and saponifying the resulting cinnamyl esters. Cinnamic alcohol is a crystalline body, although commercial specimens frequently contain traces of impurities which prevent crystallisation. It has the following characters —... 

The electrochemical oxidation is often more sensitive to the reaction conditions than to the substituents. Platinum electrodes are recommended for methoxylation and the equivalent acetoxylation procedures.290 In acetonitrile buffered by hydrogen carbonate ion, 3,4-diethylfuran affords the 2,5-dihydroxy-2,5-dihydro derivative (84%) and Jones oxidation readily leads to diethylmaleic anhydride in what is claimed to be the best general method for such conversions.291 In unbuffered methanol and under current density control, the oxidation of 2-methylfuran appears to eliminate the methyl group since the product is the acetal-ester 111 also obtained from methyl 2-furoate.292 If sodium acetate buffer is used, however, the methyl group is retained but oxidized in part to the aldehyde diacetate 112 in a... 

A brief exposure of diacetate derivatives of aromatic aldehydes to MW irradiation on neutral alumina surface rapidly regenerates aldehydes (Scheme 6.5) [36], The selectivity in these deprotection reactions is achievable by merely adjusting the time of irradiation. As an example, for molecules bearing acetoxy functionality (R = OAc), the aldehyde diacetate is selectively removed in 30 s, whereas an extended period of 2 min is required to cleave both the diacetate and ester groups. The yields obtained are better than those possible by conventional heating methods and the procedure is applicable to compounds bearing olefmic moieties such as cinnamaldehyde diacetate [36],... 

Acylals (geminal diacetates) are frequently used as protecting groups for aldehydes because of their stability to neutral and basic conditions [8]. In addition, the acylal functionality can be converted into other useful functional groups [9]. For example a novel synthesis of chiral allylic esters has been developed using palladium-catalyzed asymmetric allylic alkylation of gem-diesters [10]. The allylation of... 

To address limitations in the use of glyceraldehyde acetonide (43) as a three-carbon chiral building block, butane-2,3-diacetal-protected glyceraldehyde (44, R1 = R2 = H) has been prepared. It undergoes diastereoselective aldol reactions with a range of carbonyl compounds esters, thioesters, and ketones. The work has been extended (g) to other derivatives such as the a-substituted aldehyde (44, R1 = Me, allyl) and the methyl ketone (44, R2 = Me).122a,b... 

The asymmetric hydrolysis of (exo,exo)-7-oxabicyclo[2.2.1]heptane-2,3-dimethanol, diacetate ester (37) to the corresponding chiral monoacetate ester (38) (Fig. 12B) has been demonstrated with lipases [61]. Lipase PS-30 from P. cepacia was most effective in asymmetric hydrolysis to obtain the desired enantiomer of monoacetate ester. The reaction yield of 75 M% and e.e. of >99% were obtained when the reaction was conducted in a biphasic system with 10% toluene at 5 g/liter of the substrate. Lipase PS-30 was immobilized on Accurel PP and the immobilized enzyme was reused (5 cycles) without loss of enzyme activity, productivity, or e.e. of product (38). The reaction process was scaled up to 80 liters (400 g of substrate) and monoacetate ester (38) was isolated in 80 M% yield with 99.3% e.e. The product was isolated in 99.5% chemical purity. The chiral monoacetate ester (38) was oxidized to its corresponding aldehyde and subsequently hydrolyzed to give chiral lactol (33) (Fig. 12B). The chiral lactol (33) obtained by this enzymatic process was used in chemoenzymatic synthesis of thromboxane A2 antagonist (35). 

The moisture- and air-stable ionic liquids, l-butyl-3-methylimidazolium tetra-lluoroborate [bmim]BF and l-butyl-3-methylimidazolium hexafluorophosphate [bmim]PFg, were used as green recyclable alternatives to volatile organic solvents for the ethylenediaimnonium diacetate-catalyzed Knoevenagel condensation between aldehydes or ketones with active methylene compounds. As described by Su et al. [57], the ionic hquids containing a catalyst were recycled several times without decrease in yields and reaction rates. In the case of 2-hydroxybenzaldehyde, the reactions led to the formation of 3-substituted coumarin derivatives in high yields of up to 95% (Scheme 17.11). When ethyl cyanoacetate was used, 2-imino-27f-l-benzopyran-3-carboxyhc acid ethyl ester was formed. 

Compound (9) showed, in the infrared, no absorption corresponding to a free aldehyde group. On acetylation, it gave a crystalline monoacetate (acetylated on the hemiacetal hydroxyl group) and the diacetate. The monoacetate yielded a crystalline methylsulfonyl ester. 

PHOSPHORIC ACID, DIMETHYL ESTER, WITH (E)-3-HYDROXY-A, A -DIMETHYLCROTONAMIDE (141-66-2) CsHisNOjP May react violently with antimony(V) pentafluoride. Inconqiatible with nitrates. Corrosive to cast iron, mild (low carbon) steel, brass, and stainless steel 304. Slow hydrolysis in water. Decomposes in storage at temperatures above 135°F/55°C. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, glycols, isocyanates, ketones, lead diacetate, magnesium, maleic anhydride, nitrates, nitromethane, phenols, silver nitrate, vinyl acetate. 

The reductive amination between aldehyde 45 and methyl O-methyl-L-tyrosine ester gave the amino phenol 41, which incorporates all carbon atoms of the synthetic target FR901483. The crucial transformation in the synthetic pathway was the following oxidative cyclization of aminophenol 41. After much experimentation, it was found that exposure of a solution of 41 in hexafluoro-2-propanol to iodobenzene diacetate at room temperature resulted in the formation of azaspiro[4.5]decadienone... 

In 1989, a highly enantioselective aldol reaction of achiral silyl enol ethers of thiol esters with achiral aldehydes was developed by using a novel chiral promoter system consisting of chiral diamine-coordinated tin(II) triflate and tributyltin fluoride (or dibutyltin diacetate) [23]. When the silyl enol ether 16 of S-ethyl ethanethioate was treated with PhCHO in the presence of stoichiometric amounts of tin(II) triflate, (S)-l-methyl-2-[(piperidin-l-yl)-methyl]-pyrrolidine (18), and tributyltin fluoride, the aldol reaction proceeded at -78 °C to afford the corresponding adduct 17 in 78% yield with 82% ee (Scheme 4). 

Hexylene glycol diacetate. See 1,3-Nonanediol acetate, mixed esters Hexylenic aldehyde. See 2-Hexenal Hexyl ethanoate. See Hexyl acetate Hexyl ether. See n-Hexyl ether n-Hexyl ether... 

The oxidation of a ( )-flavanone with Tl(ni) nitrate, Pb tetracetate, phenyliodonium diacetate (PIDA), or [hydroxyl(tosyloxy)iodo]benzene in trimethyl orthofonnate affords the corresponding ( )-2,3-dihydrobenzo[h]furan derivative as a major product. The structures, including the relative stereochemistry, and a plausible mechanism of formation are reported. The preferred formation of a flavone from the ( )-flavanone by PIDA is explained by quantum-chemical calculations on the intermediate formed by the addition of this reagent to the enol ether derivative of the ( )-flavanone." Formation of mixed anhydrides by rapid oxidation of aldehydes, activated by pivalic acid, Bu OCl in presence of pyridine and MeCN is catalysed by TEMPO (2,2,6,6-tetramethylpiperidin-l-oxyl). The anhydrides can be converted in situ to esters, secondary, tertiary or Weinreb amides in high yield. Oxidation of the aldehyde to 2-propyl esters is also possible using only catalytic amounts of pivalic acid." ... 

When the monoacetate (XXIV) reacts with periodate cyclization between the C-1 hydroxyl and C-8 aldehyde groups in the initial product gives the hemiacetal (XXV). The free aldehyde group is readily oxidized to give an acid whose methyl ester (XXVII R = H) can be acetylated to give the diacetate (XXVII R = Ac). The NMR-spectral data show... 

Pineapple Ananas comosus, Bromeliaceae) aroma consists of about 200 alcohols, esters, lactones, aldehydes, ketones, monoterpenes, sesquiterpenes and other volatiles. About 80% of the total volatile substances are esters. The main components in the green fruit are ethyl acetate, ethyl 3-(methylthio)propionate (8-189) with a distinctive pineapple aroma and ethyl 3-(acetoxy)hexanoate (8-190). The ripe fruit contains, as the main esters, ethyl acetate, (2J ,3i )-butane-2,3-diol diacetate (8-191) and ketone 3-hydroxy-butan-2-one. An important compound for the typical character of pineapple aroma, as in strawberry aroma, is 2,5-dimethyl-4-hydroxy-2//-furan-3-one (furaneol), present as a glycoside, and 2,5-dimethyl-4-methoxy-2H-furan-3-one. 

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