Olefination Of Aldehydes Research Articles

HEAT-INDUCED CHANGES IN VOLATILES OF MILK AND EFFECTS OF THERMAL PROCESSING ON MICROBIAL METABOLISM OF YOGURT

Flavor and texture of yogurt are highly associated with the consumer acceptability. The volatiles in the headspace of heated milk and yogurt were analyzed to assess the effects of preheat treatment on microbial metabolism. Seventeen and 25 volatiles were found in fresh raw milk and reconstituted milk using Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry, while 23 and 31 volatiles were investigated in their yogurt products, respectively. The levels of aldehydes, methyl ketones, alkanes, olefinic aldehydes and ketenes increased in liquid milk with increasing the intensity of heat treatments. Meanwhile, their levels in respective yogurt showed similar changes. 2-Pentanone, 2,3-butanedione and 2,3-pentanedione that were metabolized by starter culture organisms decreased due to increasing the intensity of heat treatments, suggesting that these heat treatments can inhibit the flavor metabolism of organisms. By analyzing the texture profile of yogurt, hardness, adhesiveness and gumminess increased with increasing the intensity of heat treatments; however, little difference was observed between the raw milk samples and the reconstituted milk samples. PRACTICAL APPLICATIONS This study demonstrated the differences in flavor impact compounds and textural properties of yogurt due to the preheat treatment and microbial metabolism. Results explain the source of volatile compounds in yogurt processing. Information on the changes in flavor as affected by heating processes would help in understanding their suitability in yogurt production. The research on flavor metabolism would shed light on the final application of some approaches to improve yogurt such as modification of milk medium, screening of the flavor-producing bacteria and the processing control of flavor production. Also, the finding could be used in the production of flavoring agent.

Update: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin Using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

AbstractThe facile synthesis of polyethylene glycol (PEG)‐immobilized iron(II) porphyrin using a copper‐catalyzed azide‐alkyne [3+2] cycloaddition “click” reaction is reported. The prepared complex 5 (PEG‐C51H39FeN7O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG‐supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss.

Synthesis of new olefin chalcone derivatives as antitumor, antioxidant and antimicrobial agents

Chalcone is a unique template that is associated with several biological activities. Claisen–Schmidt condensation of olefin aldehyde 3 and various mono, disubstituted and heterocyclic acetophenones afforded novel olefin chalcones. Synthesized compounds were subjected for ADME prediction by computational method which revealed that these molecules can be considered as a potential drug. Out of the 21 compounds screened, compounds 5u, 5g, 5c and 5e have shown significant cytotoxicity against Hep 3BPN 7, compounds 5j, 5i, 5n and 5o showed good cytotoxicity against HL 60 P 58. Compounds 5f, 5c, 5e and 5b showed potent cytotoxicity against Hela B 75. Antioxidant activity was assessed using three methods, namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical scavenging and ferric reducing antioxidant power (FRAP). The result shows that all these compounds possess significant antioxidant activity. Compounds 5k, 5s, 5a and 5c showed promising antibacterial activity. Compounds 5k, 5u and 5f could be considered as chemopreventive agents.

Organocatalytic sequential α-aminoxylation and cis-Wittig olefination of aldehydes: synthesis of enantiopure γ-butenolides

A short route to enantiopure γ-butenolides (up to 99% ee) has been developed from readily available starting materials. The strategy involves a sequential organocatalytic α-aminoxylation followed by cis-Wittig olefination of aldehydes. The utility of this protocol has been demonstrated in the asymmetric synthesis of trans-(+)-cognac lactone with high enantiomeric purity.

Stereoselective synthesis of hydroxy stilbenoids and styrenes by atom-efficient olefination with thiophthalides

The synthesis of stilbenoids and styryl carboxylic acids is accomplished with high E-stereoselectivity by olefination of aldehydes with thiophthalides under basic conditions. The olefination is highly atom-efficient as it only loses elemental sulfur during the reaction. This olefination, in conjunction with retro Kolbe-Schmitt reaction, allows facile synthesis of E-hydroxystilbenoids with minimal employment of protecting groups. This study also discloses two important findings: formation of i) 4-methylsulfanyl isocoumarins and ii) an 2-arylindenone.

Organocatalytic stereoselective synthesis of passifloricin A.

The enantioselective synthesis of passifloricin A has been achieved in high diastereomeric excess. The 1,3-polyol moiety was constructed by iterative proline-catalyzed sequential α-aminoxylation and Horner-Wadsworth-Emmons (HWE) olefination of aldehydes while the synthesis of lactone moiety was achieved by ring-closing metathesis (RCM).

The stereocontrolled total synthesis of spirastrellolide A methyl ester. Fragment coupling studies and completion of the synthesis

The spirastrellolides are a novel family of structurally unprecedented marine macrolides which show promising anticancer properties due to their potent inhibition of protein phosphatase 2A. In the preceding paper, a modular strategy for the synthesis of spirastellolide A methyl ester which allowed for the initial stereochemical uncertainties was outlined, together with the synthesis of a series of suitably functionalised fragments. In this paper, the realisation of this synthesis is described. Two alternative coupling strategies were explored for elaborating the C26-C40 DEF bis-spiroacetal fragment: a modified Julia olefination of a C26 aldehyde with a C17-C25 sulfone, and a Suzuki coupling of a C25 trialkylborane with a C17-C24 vinyl iodide, which also required the development of a double hydroboration reaction to install the C23/C24 stereocentres. The latter proved a significantly superior strategy, and was fully optimised to provide a C17 aldehyde which was coupled with a C1-C16 alkyne fragment to afford the C1-C40 carbon framework. The BC spiroacetal was then installed within this advanced intermediate by oxidative cleavage of two PMB ethers with spontaneous spiroacetalisation, which also led to unanticipated deprotection of the C23 TES ether. The ensuing truncated seco-acid was cyclised in high yield to construct the 38-membered macrolactone under Yamaguchi macrolactonisation conditions, suggesting favourable conformational pre-organisation. Exhaustive desilylation provided a crystalline macrocyclic pentaol, revealing much about the likely conformation of the macrolactone in solution. Attachment of the remainder of the side chain proved challenging, potentially due to steric hindrance by this macrocycle; an olefin cross-metathesis to install an electrophilic allylic carbonate and subsequent π-allyl Stille coupling with a C43-C47 stannane achieved this goal. Global deprotection completed the first total synthesis of (+)-spirastrellolide A methyl ester which, following detailed NMR correlation with an authentic sample, validated the full configurational assignment. A series of simplified analogues of spirastrellolide incorporating the C26-C47 region were also prepared by π-allyl Stille coupling reactions.

A Modified Protocol for the Aldehyde Olefination Reaction using Ionic liquid as Reaction Medium

artykul z : Annales Universitatis Mariae Curie-Sklodowska. Sectio AA, Chemia Vol. 67 (2012), 1/2, s. 123-129

An organocatalytic route to the synthesis of (6 S)-5,6-dihydro-6-[(2 R)-2-hydroxy-6-phenylhexyl]-2 H-pyran-2-one and ravensara lactones

An organocatalytic enantioselective synthesis of the title compounds has been achieved. The stereogenic centers were generated by the iterative use of proline catalyzed α-aminoxylations and HWE olefination of aldehydes while the lactone ring was constructed by ring closing metathesis.

Retraction: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

Retraction: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

The stereoselective total synthesis of (+)-18-(6 S,9 R,10 R)-bovidic acid

An expedient stereoselective total synthesis of 18-carbon (+)-(6 S,9 R,10 R)-bovidic acid, isolated from the pelage and skin of a gaur B. frontalis is described using l-proline catalysed sequential α-aminoxylation and Horner–Wadsworth–Emmons olefination of aldehyde, cross metathesis and tandem Sharpless asymmetric dihydroxylation-S N2 cyclization reaction as the key steps.

ChemInform Abstract: Ruthenium—Porphyrin‐Catalyzed Carbenoid Transfer Reactions

AbstractReview: ca. 80 refs.

Contrasting Reactivity of 2-Mesityl-1,8-Naphthyridine (Mes-NP) with Singly-Bonded [RhII–RhII] and [RuI–RuI] Compounds

Reaction of cis-[Rh2(CH3COO)2(CH3CN)6](BF4)2 with two equivalents of 2-mesityl-1,8-naphthyridine (Mes-NP) affords trans-[Rh2(CH3COO)2(Mes-NP)2](BF4)2 (1). X-ray structure reveals weak Rh–C(ipso) interaction, and a short Rh–Rh distance. The same ligand, in contrast, oxidatively cleaves the Ru–Ru bond in cis-[Ru2(CO)4(CH3CN)6](BF4)2 and results in trans-[Ru(Mes-NP)2(CH3CN)2](BF4)2 (2). Both compounds adopt trans geometry to relieve the steric strain. Compound 2 exhibits moderate activity for the alcohol oxidation and aldehyde olefination reactions.

Z-Selective Horner–Wadsworth–Emmons-type Reaction Using a 10-P-5 Phosphorane Bearing Bidentates Derived from 1-Naphthol

A Horner–Wadsworth–Emmons-type 10-P-5 phosphorane reagent bearing bidentate ligands from 1-naphthol was prepared and examined in the olefination of aldehydes. Z-Selectivity was generally high excep...

Enantio‐ and Diastereocontrolled Total Synthesis of (+)‐Strictifolione

AbstractA concise and practical enantioselective synthesis of (+)‐strictifolione has been achieved in high diastereomeric excess using Jacobsen's hydrolytic kinetic resolution, proline‐catalyzed sequential α‐aminoxylation and Horner–Wadsworth–Emmons olefination of aldehyde and cross olefin/ring‐closing metathesis as the key steps.

Bimetallic Catalysis Involving Dipalladium(I) and Diruthenium(I) Complexes

Dipalladium(I) and diruthenium(I) compounds bridged by two [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L) ligands have been synthesized. The X-ray structures of [Pd(2)L(2)][BF(4)](2) (1) and [Ru(2)L(2)(CO)(4)][BF(4)](2) (2) reveal dinuclear structures with short metal-metal distances. In both of these structures, naphthyridine bridges the dimetal unit, and the site trans to the metal-metal bond is occupied by weakly coordinating oxygen from the amido fragment. The catalytic utilities of these bimetallic compounds are evaluated. Compound 1 is an excellent catalyst for phosphine-free, Suzuki cross-coupling reactions of aryl bromides with arylboronic acids and provides high yields in short reaction times. Compound 1 is also found to be catalytically active for aryl chlorides, although the corresponding yields are lower. A bimetallic mechanism is proposed, which involves the oxidative addition of aryl bromide across the Pd-Pd bond and the bimetallic reductive elimination of the product. Compound 1 is also an efficient catalyst for the Heck cross-coupling of aryl bromides with styrenes. The mechanism for aldehyde olefination with ethyl diazoacetate (EDA) and PPh(3), catalyzed by 2, has been fully elucidated. It is demonstrated that 2 catalyzes the formation of phosphorane utilizing EDA and PPh(3), which subsequently reacts with aldehyde to produce a new olefin and phosphine oxide. The efficacy of bimetallic complexes in catalytic organic transformations is illustrated in this work.

Ruthenium-Porphyrin-Catalyzed Carbenoid Transfer Reactions

Ruthenium-porphyrins are effective catalysts for a wide varietyof carbenoid transfer reactions, such as alkene cyclopropanation,carbon-hydrogen, nitrogen-hydrogen, or sulfur-hydrogen (X-H,X = C, N, S) bond insertion, diazo coupling, carbonyl or azomethineylide formation/1,3-dipolar cycloaddition, and halonium,sulfonium, or ammonium ylide formation/[2,3]-sigmatropicrearrangement reactions. Extensive studies have demonstrated that ruthenium-porphyrinsexhibit high stability, high product turnover numbers, and remarkableselectivity in catalytic carbenoid transfer reactions. The catalysishas been successfully applied to the synthesis of organic buildingblocks and natural products, and to the modification of peptidesand proteins. 1 Introduction 2 Catalyst Types 3 Cyclopropanation Reactions 4 Carbon-Hydrogen, Nitrogen-Hydrogen, andSulfur--Hydrogen Bond Insertion Reactions 5 Alkene Formation Reactions 5.1 Coupling of Diazo Compounds 5.2 Olefination of Aldehydes 6 Ylide Formation and Subsequent Reactions 6.1 Carbonyl Ylide Formation/1,3-Dipolar Cycloaddition 6.2 Azomethine Ylide Formation/1,3-Dipolar Cycloaddition 6.3 Halonium Ylide Formation/[2,3]-SigmatropicRearrangement 6.4 Sulfonium or Ammonium Ylide Formation/[2,3]-SigmatropicRearrangement 7 Comparison of (Carbene)ruthenium-Porphyrin Complexes withIron and Osmium Analogues 8 Conclusion

ChemInform Abstract: Enantioselective Synthesis of syn/anti‐1,3‐Amino Alcohols via Proline‐Catalyzed Sequential α‐Aminoxylation/α‐Amination and Horner—Wadsworth—Emmons Olefination of Aldehydes.

AbstractThe target compounds are prepared with anti‐ or syn‐selectivity using D‐ or L‐proline as a catalyst, respectively.

Asymmetric Synthesis of (R)-Antofine and (R)-Cryptopleurine via Proline-Catalyzed Sequential α-Aminoxylation and Horner−Wadsworth−Emmons Olefination of Aldehyde

Naturally occurring phenanthroindolizidine alkaloids (R)-antofine and phenanthroquinolizidine alkaloids (R)-cryptopleurine have been synthesized in high optical purity via proline-catalyzed sequential α-aminoxylation and Horner-Wadsworth-Emmons olefination of aldehyde. Both enantiopure forms of proline are commercially available, and thus, in principle, both isomers of antofine and cryptopleurine can be accessed with the new method.

An organocatalytic route to the synthesis of lactone moiety of compactin and mevinolin

An efficient synthesis of lactone moiety of compactin has been achieved. The stereogenic centers were generated by means of iterative proline-catalyzed sequential α-aminoxylation and Horner–Wadsworth–Emmons (HWE) olefination of aldehydes.