نتایج جستجو برای: unsaturated ester
تعداد نتایج: 53007 فیلتر نتایج به سال:
Microalgae oil serves as a feedstock for a biorefinery approach to mid-chain (di-)carboxylic acid esters, currently only accessible via demanding synthetic routes. Via the butenolysis of monoand poly-unsaturated fatty acids, short-chain unsaturated fatty acid methyl esters and monoand di-enes were produced in a high selectivity. These olefins were further processed into value added linear mid-c...
The first N-Heterocyclic Carbene (NHC) mediated activation of stable carboxylate esters to generate enolate intermediates is disclosed. The catalytically generated arylacetic ester enolates undergo enantioselective reactions with α,β-unsaturated imines.
A Michael-type reaction of β,γ-unsaturated α-keto ester and α-nitro ketone was established. With a thiourea catalyst derived from cinchona alkaloid, the reactions afford products in 47-94% yields with 68-96% ee.
β-Isocupreidine (β-ICD) catalyzed asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters afforded ester-substituted functionalized dihydropyran derivatives in high yields along with high enantioselectivities under mild conditions.
Chronic blepharitis has been a difficult disease to define either microbiologically or biochemically. Sterols from meibomian secretions of normal subjects and patients were analyzed, and important differences were observed. Based on analyses of these secretions, two significantly different (P less than 0.001) types of normal subjects were found, those with and those without cholesterol esters [...
The cholesteryl ester-rich, intracellular inclusions that characterize atherosclerotic plaque are capable of existing in a metastable, relatively fluid state for long periods of time. We have developed an analytical model which explains this metastability, and other aspects of the phase behavior, of physiologically relevant, phospholipid-stabilized dispersions of cholesteryl ester mixtures. The...
The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) organocatalyst is described. The low acidity of the alkyl thiol pro-nucleophiles is overcome by the high Brønsted basicity of the catalyst and the chiral scaffold/thiourea hydrogen-bond donor moiety provides the required enant...
Phosphonate reagents were developed for the two-carbon homologation of aldehydes or ketones to unbranched- or methyl-branched α,β-unsaturated aldehydes. The phosphonate reagents, diethyl methylformyl-2-phosphonate dimethylhydrazone and diethyl ethylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condens...
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