Acrylates acylation

Umbraculumin C (90), characterized by the presence of a trans-3-(methylthio)-acrylic acyl residue, is a diacylglycerol obtained from the skin of the opisthobranch mollusc Umbraculum mediterraneum [96]. Taylor and co-workers determined the absolute configuration of 90 by total synthesis [97] while Sodano et al. reached the same conclusion by derivatisation of the natural compound [98]. Compound 90 displayed ichthyotoxic activity against the mosquito fish at 0.1 pg/ml and should represent the deterrent of this organism against predators [96]. 

Esters, acylation of aminothiazoles, 47, 53 with aminothiazoles, 119 Ethoxy carbonylisothiocyanate, 126 Ethyl acrylate, acylation with. 54 Ethyl chloroformate, to carbamate, 51. 96, 97... 

Since the exocyclic sulfur is more reactive in the ambident anion than in A-4-thiazoIine-2-thione. greater nucleophilic reactivity is to be expected. Thus a large variety of thioethers were prepared in good yields starting from alkylhalides (e.g.. Scheme 38 (54, 91, 111, 166-179). lactones (54, 160), aryl halides (54, 152. 180, 181), acyl chlorides (54. 149, 182-184). halothiazoles (54, 185-190), a-haloesters (149. 152. 177. 191-194), cyanuric chloride (151). fV.N-dimethylthiocarbamoyl chloride (151, 152. 195. 196), /3-chloroethyl ester of acrylic acid (197), (3-dimethylaminoethyl chloride (152). l,4-dichloro-2-butyne (152), 1,4-dichloro-2-butene (152), and 2-chloro-propionitrile (152). A general... 

Mechanistic studies (6,26,27,67) have shown that the acyl enzyme species is the ring opened compound (13), which can tautomerize to the transientiy inhibited amino acrylate (14), and both of these species can react further to give irreversibly inactivated enzyme. Three inactivated forms of the enzyme have been detected. Two, according to labeling studies, retain the complete clavulanate skeleton and the other retains only the carbon chain of the P-lactam ring. Stmcture (15) has been suggested as one possible inactivated form. 

The formation of an enamine from an a,a-disubstituted cyclopentanone and its reaction with methyl acrylate was used in a synthesis of clovene (JOS). In a synthetic route to aspidospermine, a cyclic enamine reacted with methyl acrylate to form an imonium salt, which regenerated a new cyclic enamine and allowed a subsequent internal enamine acylation reaction (309,310). The required cyclic enamine could not be obtained in this instance by base isomerization of the allylic amine precursor, but was obtained by mercuric acetate oxidation of its reduction product. Condensation of a dihydronaphthalene carboxylic ester with an enamine has also been reported (311). 

A related reaction is the acylation of yA disuhstituted benzyl ketones to isobenzopyrylium salts the unsubstituted compounds yield 4-pyrones as shown in Section II,D,3,a. Another related acylation converts unsaturated esters into 2-p3U ones, e.g., ethyl, jS-dimethyl-acrylate into 4,6-dimethyl-2-pyrone. ... 

In American patents [31,32, the acylation of PS with acryl, methacrylate chloride, and a and jS-halogen pro-penylchloride has been done in the presence of AICI3 catalysis at 60-100 C. This process can be accomplished by using two methods in the presence of nonsolvent either CH2=CHCOCl, ClCHj—CH2—COCl and BF3 catalysis passed from PS as vapor or acylated material... 

Combination of lipase-catalyzed transesterification with unsaturated vinyl esters as acyl donors and ring-closing metatheses (RCMs) have also been reported [146-148]. Two groups applied this strategy for the synthesis of goniothalamin from cinnamaldehyde [147,148]. The key steps were a transesterification using vinyl acrylate as acyl donor, followed by an RCM, as depicted in Figure 6.55. 

The resulting complexes can be effectively employed as single component catalysts to homopolymerize ethylene or copolymerize ethylene with acrylates [50, 51] and a variety of other polar monomers including vinyl ethers, [51,52] vinyl fluoride [53], iV-vinyl-2-pyrrolidinone, and AMsopropylacrylamide [54], In fact, the resulting catalysts are so robust that they can be used as single component catalysts in aqueous emulsion homo-polymerization of ethylene and copolymerization of ethylene with norbomenes and acylates [55]. 

Acrylic acid, /ro i-/3-(o-NiTROPHEira.)-a-PHENYL-, 35, 89 Acrylonitrile, 30, 80 36, 6 Acrylonitrile, triphenyl-, 31, 52 Acylation of ethanolamine with phthalic anhydride, 32, 19 Acyloin reaction, 36, 79 2-Acylpyridines, phenylhydrazones of,... 

Thus far, the use of acrylates and related acyl derivatives as nucleophilic partners in hydrogen-mediated reductive aldol coupling has been unsuccessful due to competitive conventional hydrogenation. Although the mechanistic basis of these results remains unclear, it may be speculated that for acrylates and struc-... 

Scheme 22.10 Attempted reductive aldol coupling of ethyl acrylate and related acyl derivatives.

Arylation of activated double bonds with diazonium salts in the presence of copper catalysts is known as the Meerwin reaction. The reaction is postulated to either proceed through an organocopper intermediate or through a chlorine atom transfer from chiral CuCl complex to the a-acyl radical intermediate. Brunner and Doyle carried out the addition of mesityldiazonium tetrafluoroborate with methyl acrylate using catalytic amounts of a Cu(I)-bisoxazoline ligand complex and were able to obtain 19.5% ee for the product (data not shown) [79]. Since the mechanism of the Meerwin reaction is unclear, it is difficult to rationalize the low ee s obtained and to plan for further modifications. 

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