Acrylic ester moiety

Such an intramolecular strategy was initially tested employing alkyl-substituted methylenecyclopropanes bearing a terminal acrylate ester moiety within the substituent, e.g. 4-(2-methyl-enecyclopropyl)butyl propenoate (3). This compound reacts completely within four hours to yield the bicyclic lactone 4 when (t -allyl)(t/ -cyclopentadienyl)palladium (5 mol %) is employed at 144°C. ° ... 

Kopsia profunda and Kopsia dasyrachis are sources of new dehydropleiocarpine-type alkaloids which are characterized by the presence of a double bond across the C(16)/C(17) bridge. Alkaloids of this group include kopsidasine (212) and its Moxide (213) from K. dasyrachis [158] and MO tnethoxycarbonyl-l 1,12-niethylenedioxy-A -kopsinine (214), MI)-niethoxycarbonyl-l2-methoxy-A -kopsinine (216), and /V( I )-niethoxycarbonyl-12-hydroxy-A -kopsinine (218), and the A -oxides of 214 and 216 (215 and 217, respectively) from K. profunda [159,160]. These alkaloids show the typical olefinic carbon resonances as well as the vinylic-H resonance associated with the acrylic ester moiety. A similar compound, kopsijasmine (219) has also been obtained from the Thai species, K. Jasminiflora [150]. 

For the construction of the I ring, the vinylic group introduced to activate the y-hydroxy epoxide moiety of 28 towards cyclization is an acrylic ester residue, which concomitantly allows cyclization on the allylic position, with formation of the tricyclic compound 29 containing the IJK fragment of the natural product, and fur-... 

One such agent is prepared by NBS and peroxide bromination of ethyl 4-chiorophenylacetate (108) to give 109. This is converted by sodium hydride to the benzylic carbene, which is inserted into the double bond of ethyl acrylate to give cis-cyclopropane 110. Partial saponification cleaves the less hindered ester moiety to give 111. This is next converted to the alkoxyimide (112) on reaction with diethyl carbonate and diammonium phosphate. Stronger base (NaOEt)... 

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. 

Electroreduction of the cobalt(II) salt in a mixture of either dimethylform-amide-pyridine or acetonitrile-pyridine as solvent, often in the presence of bipyridine, produces a catalytically active cobalt(I) complex which is believed to be cobalt(I) bromide with attached bipyridine ligands (or pyridine moieties in the absence of bipyridine). As quickly as it is electrogenerated, the active catalyst reduces an aryl halide, after which the resulting aryl radical can undergo coupling with an acrylate ester [141], a different aryl halide (to form a biaryl compound) [142], an activated olefin [143], an allylic carbonate [144], an allylic acetate [144, 145], or a... 

The irons selectivity in the Honier-Wniisworth-Fmnums reaction can he reversed by structural variation in the phosphonic ester moiety, the so called StilPGetmari variant. In this case tritluoro-substi-tuted ethoxy residues are introduced in the form of phosphonic ester 41, providing access to r/5 substituted acrylic esters. 

The Morita-Baylis-Hillman (MBH) reaction is the formation of a-methylene-/ -hydroxycarbonyl compounds X by addition of aldehydes IX to a,/ -unsaturated carbonyl compounds VIII, for example vinyl ketones, acrylonitriles or acrylic esters (Scheme 6.58) [143-148]. For the reaction to occur the presence of catalytically active nucleophiles ( Nu , Scheme 6.58) is required. It is now commonly accepted that the MBH reaction is initiated by addition of the catalytically active nucleophile to the enone/enoate VIII. The resulting enolate adds to the aldehyde IX, establishing the new stereogenic center at the aldehydic carbonyl carbon atom. Formation of the product X is completed by proton transfer from the a-position of the carbonyl moiety to the alcoholate oxygen atom with concomitant elimination of the nucleophile. Thus Nu is available for the next catalytic cycle. 

Still and Schneider employed Ireland-Claisen rearrangement in the total synthesis of ( )-frullanolide (ll)6 (Scheme 1.3f). The key step of the synthesis is efficient Ireland-Claisen rearrangement of the P-pyrrolidinopropionate ester 12. The triethylsilylketene acetal rearranged in toluene at reflux and the pyrrolidine moiety was eliminated after stirring with a mixture of dimethyl sulfate and potassium carbonate in methanol to afford the a-substituted acrylic ester (13). Saponification followed by iodolactonization gave the iodolactone 14, which upon treatment with DBU led to ( )-frullanolide. 

The pendant functions listed in Figure 3 are often useful and of synthetic interest per se. For example, methacrylate and acrylate esters are polymerizable (cross-linking sites) [19-21] the cinnamate is photorespon-sive (for the photo-induced dimerization of its unsaturated groups) [20] oligo(oxyethylene) [25-27] and carbohydrate groups [35] give hydrophilic and water-soluble polymers, whereas perfluoroalkyl moieties [32-34] enhance hydrophobicity. Thus, poly(vinyl ethers) with cinnamate functions... 

The epoxide moieties of vemonia oil play an important role in making acrylates, groups useful in making UV curing formulations. For instance, the methacrylate ester of vernonia oil is synthesized by reaction with methacrylic acid in the presence of a tertiary amine. The acrylate ester is UV active and is therefore easily polymerized through the acrylate vinyl moieties. The mechanism of making vernonia oil-based acrylates is shown in Figure 15. 

Achiwa reported a short synthesis of pyrrolizidine derivatives by the cycloadditions using a nonstabilized azomethine ylide 23 (m = 1) (82CPB3167). When the trimer of 1-pyrroline is treated with a silylmethyl triflate, N-alkylation of the 1-pyrroline takes place. Then the resulting iminium salt is desilylated with fluoride ion in the presence of ethyl acrylate to give ethyl pyrrolizidine-l-carboxylate 295 as a mixture of stereoisomers (28%). After the epimerization of 295 with LDA, the ester moiety is reduced with lithium aluminum hydride in ether to provide (+ )-trachelanthamidine (296). A double bond can be introduced into 295 by a sequence of phenyl-selenylation at the 1-position, oxidation with hydrogen peroxide, and elimination of the selenyl moiety. The 1,2-dehydropyrrolizidine-l-carboxylate 297 is an excellent precursor of (+ )-supinidine (298) and (+)-isoretronecanol (299). Though in poor yield, 297 is directly available by the reaction of 23 with ethyl 3-chloropropenoate. 

Local reactions take place, for instance, in unconventional lithography approaches. Here, the surface of a polystyrene-Woc -poly(ter/-butyl acrylate) (PS69o-fr-PtBA12io) block copolymer film comprising reactive ter/-butyl ester moieties at the film surface (skin layer of 8 nm thickness) is locally hydrolyzed by a reactant (trifluoro acetic acid) that is delivered by a soft elastomeric stamp, as shown in Fig. 4.38. Thus, the surface is locally modified to yield poly(acrylic acid), which possess higher friction forces than the unreacted tert-butylester region. 

There are in general two ways to synthesize side chain polymers, polymerization of peptide-functional monomers or introduction of the peptide moiety afterwards, by grafting. The latter technique is based on the synthesis of polymers containing some form of functionality in the side chain, normally an activated ester moiety, which can further react with a peptide. The most commonly used method for the polymerization of monomers containing active esters is free radical polymerization. In particular many activated acrylate esters have been polymerized in this manner [12] (Table 1) for use in a wide variety of applications, from the preparation of polymer drug conjugates [13,14] to supports for solid phase peptide synthesis [15,16]. 

Cyclic allylic disulfide readily underwent the R-ROP due to the facile cleavage of the bond between allylic carbon and sulfur atom, resulting in the production of polysuffides with exo-methylene groups (3, 41, 42). Acrylate-based cyclic allylic sulfide also showed a high radical polymerizability (3, 43). The copolymerization of acrylate-based cyclic allylic sulfide with MMA and styrene produced the corresponding copolymers bearing sulfide and ester moieties in the polymer backbone (43). 

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