Methyl acrylate Diels-Alder dienes

Heteroatom functionalized terpene resins are also utilized in hot melt adhesive and ink appHcations. Diels-Alder reaction of terpenic dienes or trienes with acrylates, methacrylates, or other a, P-unsaturated esters of polyhydric alcohols has been shown to yield resins with superior pressure sensitive adhesive properties relative to petroleum and unmodified polyterpene resins (107). Limonene—phenol resins, produced by the BF etherate-catalyzed condensation of 1.4—2.0 moles of limonene with 1.0 mole of phenol have been shown to impart improved tack, elongation, and tensile strength to ethylene—vinyl acetate and ethylene—methyl acrylate-based hot melt adhesive systems (108). Terpene polyol ethers have been shown to be particularly effective tackifiers in pressure sensitive adhesive appHcations (109). 

Enamines have been observed to act both as dienophiles (46-48) and dienes (47,49) (dienamines in this case) in one-step, Diels-Alder type of 1,4 cycloadditions with acrylate esters and their vinylogs. This is illustrated by the reaction between l-(N-pyrrolidino)cyclohexene (34) and methyl t/-a i-2,4-pentadienoate (35), where the enamine acts as the dienophile to give the adduct 36 (47). In a competitive type of reaction, however, the... 

Good yields and high diastereoselectivities were obtained by using zeolites in combination with Lewis-acid catalyst [21]. Table 4.7 illustrates some examples of Diels-Alder reactions of cyclopentadiene, cyclohexadiene and furan with methyl acrylate. Na-Y and Ce-Y zeolites gave excellent results for the cycloadditions of carbocyclic dienes, and combining these zeolites with anhydrous ZnBr2 further enhanced the endo diastereoselectivity of the reaction. An exception is the cycloaddition of furan that occurred considerably faster and with better yield, in comparison with the classic procedure [22], when performed in the presence of sole zeolites. 

Table 4.7 Diels-Alder reactions of carbo-and heterocyclic dienes with methyl acrylate catalyzed by zeolites and ZnBr2-doped zeolites...

Indium trichloride [30] and methylrhenium trioxide [31] catalyze the aqueous Diels-Alder reaction of acrolein and acrylates with cyclic and open-chain dienes. Some examples of the cycloaddition of methyl vinyl ketone with 1,3-cyclohexadiene are reported in Scheme 6.18. MeReOs does not give satisfactory yields for acroleins and methyl vinyl ketones with substituents at the jS-position and favors the self-Diels-Alder reaction of diene. 

Reaction of the y9-ketosulfoxide 1201 with TMSOTf 20/DlPEA affords, in 100% yield, the diene 1202, which readily undergoes Diels-Alder reactions, e.g. with methyl acrylate [26] (Scheme 8.9). 

Inukai and Kojima (9) have studied the aluminum chloride catalyzed diene condensation of butadiene and methyl acrylate in benzene solution. The stoichiometry for this Diels-Alder reaction is... 

Ohfune and coworkers78 used Diels-Alder reactions between 2-trimethylsilyloxy-l,3-butadiene (63) and acrylate esters 64 to synthesize constrained L-glutamates which they intended to use for the determination of the conformational requirements of glutamate receptors. The reactions between 63 and acrylate esters 64a and 64b did not proceed. Changing the ethyl and methyl ester moieties into more electron-deficient ester moieties, however, led to formation of Diels-Alder adducts, the yields being moderate to good. In nearly all cases, the cycloadducts were obtained as single diastereomers, which is indicative of a complete facial selectivity (equation 22, Table 1). Other dienes, e.g. cyclopentadiene and isoprene, also showed a markedly enhanced reactivity toward acrylate 64g in comparison with acrylate 64a. 

The pioneer work on this subject using simple 1-azadienes is due to Ghosez et al. (82TL3261 85JHC69) they succeeded in reacting 1-azadienes as 47r-electron components in Diels-Alder cycloadditions. Thus, l-dimethylamino-3-methyl-l-azabuta-l,3-diene (a,/3-unsaturated hydrazone) 54 did undergo [4 + 2] cycloaddition to typical electron-poor dienophiles, e.g., methyl acrylate, dimethyl fumarate, acrylonitrile, maleic anhydride, and naphthoquinone, producing pyridine derivatives 55-57 (Scheme 14). 

In hetero-Diels-Alder reactions, the effect of ligand structure and acidity on the catalytic activity of lanthanide catalysts has been reviewed.191 The effect of different C(2)-symmetric bisoxazolines on the zinc(II)-catalysed hetero-Diels-Alder reaction of ethyl glyoxylate with conjugated 1,3-dienes has been investigated.192 The hetero-Diels-Alder reaction 4-dimethylamino-2-phenyl-l-thiabuta-1,3 -diene with methyl acrylate and /V-cnoyloxazolidinone produces cw-3,4-disubstituted 3,4-dihydro-2//-... 

Diels-Alder reactions.1 The diene undergoes uncatalyzed [4+2]cycloaddition with very reactive dienophiles, but generally a Lewis acid catalyst (ZnCl, or C2H5A1C12) is required. Thus, the catalyzed reaction of 1 with methyl acrylate proceeds at 0° to afford, after silyl ether cleavage, the cycloadducts 2 and 3. 

Examples with 2-vinylindoles are also found. Thus, the reaction of N-methyl-2-(2-methoxyvinyl)indole, as a cis-trans mixture, with acrylonitrile and ethyl and methyl acrylate gives the corresponding Diels-Alder compounds [83IJC(B)846]. With N-methyl-2-(2-nitrovinyl)indole as diene, similar reactions occur with methyl acrylate, acrylonitrile, and acrolein acetal but in these cases, the fully aromatic compounds were isolated. The cycloaddition reaction with acrolein acetal was nonregioselective and the isolated adducts had a CHO group, indicating that the acetal had been hydrolyzed (presumably during work-up). 

The hyperbaric 4 + 2-cycloaddition of 1,2,4-trioxegenated 1,3-dienes with dieno-philes, A-phenylmaleimide, and methyl and phenyl acrylates produced the expected endo-cycloadducts with excellent stereo- and regio-control.113 The high-pressure (g) Diels-Alder reactions of 3-substituted coumarins with methylbuta-1,3-dienes in water formed tetrahydro-6H-benzo[c]chromen-6-ones in high yields (85-95%).114... 

When the carbopalladation of the bicyclopropylidene is performed in the presence of methyl acrylate, the reaction takes a different course (Scheme 8.34) [79]. The 1,3-diene intermediate 75 reacts in situ with the dienophile to give the spiro[2.5]octane derivative 76. An extension of this cascade Heck-Diels-Alder reaction involving l,3-dicyclopropyl-l,2-propadiene as the alkene partner, an alkenyl or aryl halide and a dienophile has been reported [80]. 

The products formed by the co-oligomerization of acrylic esters with butadiene (102,106) provide useful information concerning the nature and configuration of the intermediates involved. Naked-nickel, methyl acrylate, and butadiene do not react together.7 However, reaction does occur if the nickel-ligand system is used. The formation of the Diels-Alder adduct between the diene and olefin (a cyclohexene derivative) can be suppressed by adding the reactants dropwise to the catalyst (Table XVI footnote C). 

Bis-silyloxy-3,4-dihydropyridines are stable dienes easily synthesized from glutarimide. The Diels-Alder reaction of azadiene 47 with iV-methylmaleimide in benzene at 60 °C gives predominantly the endo-adduct 48, whereas the selectivity is reversed in reaction with lithium trifluoromethanesulfonimide in ether giving predominantly the < vo-adduct 49 (Scheme 12) <1995SL565>. When methyl acrylate is used as the dienophile, the reaction... 

Diels-Alder reactions of the type shown in Table 15.1, that is, Diels-Alder reactions between electron-poor dienophiles and electron-rich dienes, are referred to as Diels-Alder reactions with normal electron demand. The overwhelming majority of known Diels-Alder reactions exhibit such a normal electron demand. Typical dienophiles include acrolein, methyl vinyl ketone, acrylic acid esters, acrylonitrile, fumaric acid esters (irans-butenedioic... 

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