Methyl acrylate, from reaction with butadiene

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

In Illustrations 8.3 and 8.6 we considered the reactor size requirements for the Diels-Alder reaction between 1,4-butadiene and methyl acrylate. For the conditions cited the reaction may be considered as a pseudo first-order reaction with 8a = 0. At a fraction conversion of 0.40 the required PFR volume was 33.5 m1 2 3, while the required CSTR volume was 43.7 m3. The ratio of these volumes is 1.30. From Figure 8.8 the ratio is seen to be identical with this value. Thus this figure or equation 8.3.14 can be used in solving a number of problems involving the... 

The reactions of l-t-butyl-3-methylallene with several alkenes, e.g. IV-phenylmalei-mide, acrylonitrile and methyl acrylate, afforded exclusively [4 + 2] cycloadducts of 1-t-butyl-l,3-butadiene, which had been formed from l-t-butyl-3-methylallene by a [1,3] sigmatropic rearrangement12. The reaction of l-t-butyl-3-methylallene with 1,1-dichloro-2,2-difluoroethene occurred more rapidly than the hydrogen shift, which allowed the... 

Density functional theory has been used to investigate the Diels-Alder reactions of triazolinedione with s-cis- and. y-fran -butadiene. " Combined quantum mechanics-molecular mechanics calculations have been used to investigate the asymmetric Diels-Alder reaction of cyclopentadiene with the complex dienophiles AICI3-methyl acrylate and methoxyaluminium dichloride-acrolein.Equilibrium constants have been determined for the molecular complexes formed from 1-alkyl-1-(2-naphthyl)ethenes and 1-vinylnaphthalene with TCNE in C1(CH2)2C1 at 27.1 °C ... 

Fig. 6.4. Transition structures of the reaction between 1,3-butadiene and methyl acrylate, calculated at the ab initio RHF/6-31G level. Total energies are in hartrees and relative energies in kcal/mol. (Reprinted from Ref. 14b, Copyright 1997, with permission from Elsevier Science.)...

The 4-phospha-1,3-butadiene 77/80 serves as an effective synthon for the unknown H-substituted nitrile ylide 79 in [3+ 2]-cycloaddition reactions with a range of electron-poor dipolarophUes (e.g., reaction with DMAD gave 78 in 80% yield). Similar yields were also obtained using methyl propiolate, azodicaboxylic esters, ethyl acrylate, and acrylonitrile (39). The reactant was generated under very mild conditions from 75 as shown below. 

In 1987, Hill and co-workers (75) reported a clever synthesis of the pentacyclic cephalotaxine analog 246 starting from the nitrostyrene derivative 98 (Scheme 42). The Diels-Alder adduct 244, obtained by the reaction of butadiene sulfone with 98, was treated with methyl acrylate to give a single stereoisomer of the nitro ester, which was reduced with zinc in etha-nolic HCl to yield the lactam 245 and further reduced by Red-AI to the corresponding pyrrolidine. Pictet-Spengler cyclization with formaldehyde gave the pentacyclic amine 246. Alternatively, the reduced pyrrolidine obtained from 245 could be formylated, cyclized to the iminium salt by a Bischler-Napieralski protocol, and finally reduced with sodium borohy-dride to 246. Nearly identical sequences have also been reported by Bryce... 

Fig. 10.7. Computed transition structures for uncatalyzed and BF3-catalyzed Diels-Alder reaction of 1,3-butadiene with methyl acrylate. Reproduced from Tetrahedron, 53, 6057 (1997), by permission of Elsevier.

In a separate study, the MIT group investigated the Diels-Alder reaction of methyl acrylate with 2-f-butyl-1,3-butadiene, assuming that the ratio of isomers produced from this diene in scCOj would be more sensitive to reaction conditions if steric interactions were important (7). Little variation in regioselectivity was observed relative to normal Diels-Alder synthesis. 

When either method of preparation was carried out in the presence of methyl acrylate products derived from a 1 1 mixture oF the 1,2-and 1,4-isomers were obtained. On the other hand, in the presence of the more reactive dienophile methyl B-cyanoacrylate the products derived from the complex were again a mixture, but from the diaza--compound only adducts derived from 1,4-dideuteriocyclobutadiene were obtained. The intermediate cyclobutadiene cannot therefore have been square or again products apparently derived frbm the 1,2- or 1,4-isomers would have resulted since there would be no distinction between the isomers. It may also be deduced that both the decomposition of the diaza-compound and the trapping of the resultant cyclo-butadiene are concerted pericycllc processes and that a biradical intermediate cannot be involved. Apparently in the presence of the less reactive dienophile interconversion of the valence isomers is more rapid than the trapping cycloaddition reaction whereas with the more reactive dienophile the converse obtains. A lower limit of... 

Another aspect of the Diels-Alder reaction that can be rationalized with FMO theory is the regiochemistry observed with unsymmetric dienes or alkenes. Equation 11.45 shows the product distribution from the cycloaddition of 2-phenyl-l,3-butadiene (97) and methyl acrylate (98). The para" product 99 (named by analogy with aromatic compounds) is the major product, but some "meta" product (100) is produced as well. ... 

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