1.3- Butadienyl acetates

Acetoxy-1,3-butadiene (1,3-butadienyl acetate) cis-trans mixture [1515-76-0] M 112.1, b 42-43 /16mm, 51-52 /20mm, 60-61 /40mm, d 4 0.9466, n g 1.4622. The commercial sample is stabilised with 0.1% of p-/er/-butylcatechol. If the material contains crotonaldehyde (by IR, used in its synthesis) it should be dissolved in Et20, shaken with 40% aqueous sodium bisulfite, then 5% aqueous... 

Methyl-lf 2-butadienyl acetate (l-acetoxy-2-methyl-1 2-butadiene)... 

The reaction of 2,3-butadienyl acetate (843) with soft carbon nucleophiles such as dimethyl malonate gives dimethyl 2,3-butadienylmalonate (844)[520]. On the other hand, the reaction of the 2,3-butadienyl phosphate 845 with hard carbon nucleophiles such as Mg and Zn reagents affords the 2-allcyl-1,3-butadiene 846[520,521]. The 3-methoxy-1,3-butadiene 848 is obtained by the reaction of the 2-methoxy-2,3-butadienyl carbonate 847 with organozinc reagent. 

Silver trifluoroacetate is a suitable catalyst for various cationic rearrangements involving multiple carbon-carbon bonds [49 5(1] In the presence of silver trifluoroacetate, 2 propynyl acetates rearrange to the butadienyl acetates to give dienes that are useful in Diels-Alder reactions [49] (equation 22)... 

Pd2+ salts are useful reagents for oxidation reactions of olefins. Formation of acetaldehyde from ethylene is the typical example. Another reaction is the formation of vinyl acetate by the reaction of ethylene with acetic acid (16, 17). The reaction of acetic acid with butadiene in the presence of PdCl2 and disodium hydrogen phosphate to give butadienyl acetate was briefly reported by Stem and Spector (110). However, 1-acetoxy-2-butene (49) and 3-acetoxy-l-butene (50) were obtained by Ishii and co-workers (111) by simple 1,2- and 1,4-additions using PdCl2/CuCl2 in acetic acid-water (9 1). 

Butadienyl acetates. These useful Diels-Aldcr dienes (2) can be obtained by isomerization of 2-propynylic acetates (1) with this silver salt or with PdCl2. The substrates (1) rearrange to allcnyl acetates (3) with CuCl. ... 

Bis(silyl)butadienyl acetals have been prepared and give hydroxy... 

Binaphthol (B1N0L)-Ti complexes 100 are found to be effective catalysts in NED D-A reactions. It catalyzes the reaction of 5-hydroxynaphthoquinone with butadienyl acetate in 86 % yield and 96 % ee of cnJo-product. This intermediate is useful in the synthesis of anthracycline antibiotics [86]. 

The DA reaction of methacrolein with 1,3-dienol derivatives was catalyzed by BINOL derived titanium complexes, giving the endo adduct with high enantiose-lectivity [155]. The reaction was performed in the absence of MS, since MS can act as an achiral catalyst in this reaction and compromise the product enantiomeric excess. Similarly, the DA reaction of juglone with butadienyl acetate catalyzed by BINOL-Ti complex proceeds in only 9% ee in the presence of MS, whereas the reaction proceeds in 76-96% ee in the absence of MS to provide the endo adducts useful for the synthesis of anthracyclines and tetracycline [155,156). The drawback of the above method is the instability of the addition products, owing to their high tendency to aromatize. Corey improved this DA reaction with quinone monoacetal as a supplant of juglone or benzoquinone [157] (Scheme 14.64). 

Based on the DFT calculations, a plausible catalytic cycle has been proposed for the Ru-catalysed hydrocarboxylative dimerization of phenylacetylene PhC=CH with AcOH, which affords (l , 3 )-l,4-diphenyl-l,3-butadienyl acetate. The calculations shed light on the impact of the substituents of the alkyne and carboxylic acid substrates and the effect of solvents on the catalyst efficiency. 

Ethyl 3,4-pentadienoate, 203 - (S) Ethyl 3,4-hexadienoate, 204 - (0) 2,2-Dimethyl-3,4-pentadienal, 204 - (7) 3-Hethyl-l,2-butadienyl acetate (l-acetoxy-3-methyl-l,2-butadiene), 205... 

Comment on the mechanism of each thermolytic step and assign the structure of X, Y and Z. What is the source of butadienyl acetate ... 

The conversion of vicinal azido selenides into tetrahydrofiirans by PhSeOTf in MeCN at room temperature is reported <96JOC7085>. 3-Butadienyl tetrahydrofiirans and a-butadienyl y-butyrolactones can be prepared by radical cyclization of P-bromopent-4-en-2-ynyl ethers and mixed acetals <96SL391>. The total synthesis of trilobacin was reported <96JOC7642>. 

Similarly, 4-bromocrotonaldehyde diethyl acetal is obtained by treatment of 1-butadienyl ethyl ether with bromine and then of the resulting intermediate with sodium ethoxide 938... 

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