Biocatalytic Reduction of Activated Cinnamic Acid Derivatives : Asymmetric reduction of C=C double bonds using Johnson Matthey enzymes

The asymmetric reduction of C=C double bonds is a sought-after chemical transformation to obtain chiral molecules used in the synthesis of fine chemicals. Biocatalytic C=C double bond reduction is a particularly interesting transformation complementary to more established chemocatalytic methods. The enzymes capable of catalysing this reaction are called ene-reductases (ENEs). For the reaction to take place, ENEs need an electron withdrawing group (EWG) in conjugation with the double bond. Especially favourable EWGs are carbonyls and nitro groups; other EWGs, such as carboxylic acids, esters or nitriles, often give poor results. In this work, a substrate engineering strategy is proposed whereby a simple transformation of the carboxylic acid into a fluorinated ester or a cyclic imide allows to increase the ability of ENEs to reduce the conjugated double bond. Up to complete conversion of the substrates tested was observed with enzymes ENE-105 and *ENE-69.

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MNDO CI study of the photoisomerization of pentadieniminium

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19902874 ◽

1990 ◽

Vol 55 (12) ◽

pp. 2874-2879 ◽

Cited By ~ 2

Author(s):

Peter Ertl

Keyword(s):

Schiff Base ◽

Double Bond ◽

Configuration Interaction ◽

Mndo Method ◽

Double Bonds

Photoisomerization mechanism in model retinal-like protonated Schiff base pentadieniminium was investigated by using MNDO method with configuration interaction. Isomerizations around various double bonds were studied and twisted biradical geometries in S0 and S1 states were optimized. Photoisomerization proceeds exclusively around the central double bond where the twisted S1 state is strongly stabilized and the S0-S1 gap is minimal.

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A stereospecific synthesis of trisubstituted double bonds

Australian Journal of Chemistry ◽

10.1071/ch9700813 ◽

1970 ◽

Vol 23 (4) ◽

pp. 813 ◽

Cited By ~ 2

Author(s):

AJ Birch ◽

B McKague

Keyword(s):

Double Bond ◽

Stereospecific Synthesis ◽

Considerable Proportion ◽

Double Bonds ◽

Steric Configuration

An aspect of the synthesis of sterically defined trisubstituted double bonds is discussed. Metal-ammonia reductions of hydropyridinium salts such as (1 ; R, R' = H or Me) result in allylic fissions, with a considerable proportion of double bond retention in its original situation and complete retention of the original steric configuration in that position.

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Chlorination of Natural Rubber in Solution with Gaseous Chlorine

Rubber Chemistry and Technology ◽

10.5254/1.3539872 ◽

1953 ◽

Vol 26 (4) ◽

pp. 902-911 ◽

Cited By ~ 3

Author(s):

C. S. Ramakrishnan ◽

D. Raghunath ◽

J. B. Pande

Keyword(s):

Double Bond ◽

Natural Rubber ◽

Cyclization Reaction ◽

Double Bonds ◽

Chlorine Atoms ◽

Reaction Stage ◽

Stage 1 ◽

Additive Reaction

Abstract The chlorination of rubber solutions by gaseous chlorine was followed by isolating the partially chlorinated products and preparing their ozonides. The ozonides were hydrolyzed, and the acids and aldehydes formed on hydrolysis were determined. By a comparison with the amounts of acids and aldehydes obtained from ozonides of unreacted rubber, the amount of residual isoprenic double bonds present was found. The loss of double bonds attending the introduction of chlorine atoms into the molecule of rubber indicates four definite stages in chlorination : (1) initial substitutive attack by chlorine, with concomitant cyclization, resulting in a loss of one double bond between two isoprenic units, (2) substitution, (3) additive reaction, and (4) essentially substitution. Chlorination of aged rubber solutions differs from the above in that the cyclization reaction (stage 1) seems to be absent.

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The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

Rubber Chemistry and Technology ◽

10.5254/1.3540165 ◽

1943 ◽

Vol 16 (4) ◽

pp. 841-847

Author(s):

A. Gantmacher ◽

S. Medvedev

Keyword(s):

Raman Spectrum ◽

Double Bond ◽

Raman Spectra ◽

Polymer Molecule ◽

Polymerization Process ◽

High Polymer ◽

Single Bond ◽

Double Bonds ◽

Continuous Background ◽

Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

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Mechanisms of Nucleophilic Attack at Carbon Nitrogen Double-Bonds: The Reaction of Benzohydrazonoyl Halides With Amines

Australian Journal of Chemistry ◽

10.1071/ch9871777 ◽

1987 ◽

Vol 40 (10) ◽

pp. 1777 ◽

Cited By ~ 4

Author(s):

AF Hegarty ◽

P Rigopoulos ◽

JE Rowe

Keyword(s):

Double Bond ◽

Nucleophilic Attack ◽

Rate Data ◽

Double Bonds ◽

Nitrogen Double Bond

Rate data for the reaction of a series of benzohydrazonoyl halides with pyrrolidine and butan- 1-amine at 303 K are presented. Linear Hammett plots were obtained with each amine. The mechanism of the reactions and the stereochemical outcome of these displacements at the carbon-nitrogen double bond are discussed.

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Catalytic Enantioselective Synthesis of 4-Amino-1,2,3,4-tetrahydropyridine Derivatives from Intramolecular Nucleophilic Addition Reaction of Tertiary Enamides

Synlett ◽

10.1055/s-0037-1610384 ◽

2018 ◽

Vol 30 (04) ◽

pp. 483-487 ◽

Cited By ~ 2

Author(s):

Shuo Tong ◽

Mei-Xiang Wang

Keyword(s):

Phosphoric Acid ◽

Asymmetric Catalysis ◽

Nucleophilic Addition ◽

Addition Reaction ◽

Enantioselective Synthesis ◽

Chiral Phosphoric Acid ◽

Substrate Engineering ◽

Nucleophilic Addition Reaction ◽

Engineering Strategy ◽

Acid Catalyzed

A general and efficient method for the synthesis of highly enantiopure 4-amino-1,2,3,4-tetradydropyridine derivatives based on chiral phosphoric acid catalyzed intramolecular nucleophilic addition of tertiary enamides to imines has been developed. We have also demonstrated a substrate engineering strategy to significantly improve the enantioselectivity of asymmetric catalysis

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Phenolation of vegetable oils

Journal of the Serbian Chemical Society ◽

10.2298/jsc100820050i ◽

2011 ◽

Vol 76 (4) ◽

pp. 591-606 ◽

Cited By ~ 26

Author(s):

Mihail Ionescu ◽

Zoran Petrovic

Keyword(s):

Fatty Acids ◽

Oleic Acid ◽

Double Bond ◽

Vegetable Oils ◽

Raw Materials ◽

Complex Mixture ◽

Double Bonds ◽

Triflic Acid ◽

Model Compounds ◽

Phenol Alkylation

Novel bio-based compounds containing phenols suitable for the synthesis of polyurethanes were prepared. The direct alkylation of phenols with different vegetable oils in the presence of superacids (HBF4, triflic acid) as catalysts was studied. The reaction kinetics was followed by monitoring the decrease of the double bond content (iodine value) with time. In order to understand the mechanism of the reaction, phenol was alkylated with model compounds. The model compounds containing one internal double bond were 9-octadecene and methyl oleate and those with three double bonds were triolein and high oleic safflower oil (82% oleic acid). It was shown that the best structures for phenol alkylation are fatty acids with only one double bond (oleic acid). Fatty acids with two double bonds (linoleic acid) and three double bonds (linolenic acid) lead to polymerized oils by a Diels Alder reaction, and to a lesser extent to phenol alkylated products. The reaction product of direct alkylation of phenol with vegetable oils is a complex mixture of phenol alkylated with polymerized oil (30-60%), phenyl esters formed by transesterification of phenol with triglyceride ester bonds (<10 %) and unreacted oil (30%). The phenolated vegetable oils are new aromatic-aliphatic bio-based raw materials suitable for the preparation of polyols (by propoxylation, ethoxylation, Mannich reactions) for the preparation of polyurethanes, as intermediates for phenolic resins or as bio-based antioxidants.

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Structural Homogeneity in Unsaturated Fatty Acids of Marine Lipids. A Review

Journal of the Fisheries Research Board of Canada ◽

10.1139/f64-021 ◽

1964 ◽

Vol 21 (2) ◽

pp. 247-254 ◽

Cited By ~ 45

Author(s):

R. G. Ackman

Keyword(s):

Fatty Acids ◽

Double Bond ◽

Polyunsaturated Fatty Acids ◽

Chain Length ◽

Unsaturated Fatty Acids ◽

Analytical Data ◽

Double Bonds ◽

Marine Origin ◽

Methyl Group ◽

Marine Lipids

Consideration of recent analytical data supports the conclusion that the longer-chain polyunsaturated fatty acids of marine origin are all structurally homogeneous in that the double bonds are cis, the double bonds methylene interrupted, and that, with the exception of the C16 chain length, the ultimate double bond will normally be three, six or nine carbon atoms removed from the terminal methyl group.

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