Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• various intermediates that are reactive towards LO2 radicals. Monomer 2 is a typical monophenolic antioxidant with stoichiometry n = 2 [19][22][23][24]. The couple dimer 6/monomer 2 showed the greatest antioxidant activity as a result of the α,β-unsaturated ketone side chain in para-position of the

• (PFd/PFm = 1.7 and IDd/IDm = 1.6) observed can be rationalized in terms of the absence of an α,β-unsaturated ketone chain in para-position of benzene rings and thus lacking the resonance stabilization of the formed phenoxyl radicals. There is no difference in the antioxidant efficiency (PFd/PFm = 1.0

• in inhibition degree (ID), i.e., in their possibility to shorten the oxidation chain length. This result can be explained with the higher reactivity of phenoxyl radicals of monomers 3 and 5, due to the absence of an α,β-unsaturated ketone chain in para-position of the phenolic –OH group (in case of 3

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• bromide gave the enyne product 166 (92%), which on further acylation of terminal alkyne with butanoyl chloride delivered compound 167 (82%). Then, it was subjected to an enyne metathesis with simple platinum salts such as PtCl2 and PtCl4 to give product 168 (79%). A subsequent reduction of the α,β

• -unsaturated ketone delivered the compound 169 (64%). Finally, aromatization of compound 169 by using potassium 3-aminopropylamide (KAPA) gave compound 170 (75%) (Scheme 26). Ring-closing metathesis (RCM): In 2003, Tae and Yang [152] have reported an efficient macrocyclization of various alkenyl derivatives

Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica

• Danny Geerdink,
• Jeffrey Buter,
• Teris A. van Beek and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2014, 10, 761–766, doi:10.3762/bjoc.10.71

• % yield over three steps. To ultimately remove the carbonyl function, we introduced the third methyl ramification in α,β-unsaturated ketone 7, preparation of which was straightforward [21]. Conjugate addition to 7 using the conditions from step A proved clearcut and gave 8 in 82% yield over three steps

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• consequence of the acidic work-up β-elimination of the OMOM group was induced resulting in α,β-unsaturated ketone 90. Despite these unsatisfactory results we continued with the synthesis of C1-epi allyl ester 93 starting from alcohol 91 employing the same reaction sequence of ester reduction, diol protection

• demanding TBDPS group by the smaller TBS group in 97 could not initiate the rearrangement either. Furthermore, α,β-unsaturated ketone 98, that was generated during the acidic work-up, did not show any conversion (Scheme 15). Conclusion In view of the results obtained we conclude that an Ireland–Claisen

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• both good yield and good diastereomeric ratio. Selective hydrogenation of the more electron rich double bond followed by reduction of the ester furnished α,β-unsaturated ketone 104 after PPTS-catalyzed elimination of water. Subsequent DIBAL-H reduction yielded the alcohol epimer 105 of barekol (107

• -divinylcyclopropane rearrangement to build up the diterpenoid cyanthin skeleton [181][182][183] like that of allocyathin B2 (226, see Scheme 26), which was isolated from bird’s nest fungi [184][185][186][187][188][189]. Starting from α,β-unsaturated ketone 219 addition of ethynylmagnesium bromide took place, followed

Physalin H from Solanum nigrum as an Hh signaling inhibitor blocks GLI1–DNA-complex formation

• Midori A. Arai,
• Kyoko Uchida,
• Samir K. Sadhu,
• Firoj Ahmed and
• Masami Ishibashi

Beilstein J. Org. Chem. 2014, 10, 134–140, doi:10.3762/bjoc.10.10

• activity can be attributed to the left part of their structures. The difference in the Hh inhibitory activity between 4 (IC50, 4.2 μM) and 6 (IC50, 0.62 μM) indicates that an α,β-unsaturated ketone unit present in the physalin structure may be a good nucleophile acceptor and contribute to the Hh inhibition

Asymmetric synthesis of a highly functionalized bicyclo[3.2.2]nonene derivative

• Toshiki Tabuchi,
• Daisuke Urabe and
• Masayuki Inoue

Beilstein J. Org. Chem. 2013, 9, 655–663, doi:10.3762/bjoc.9.74

• heptenone 12 [17][18][19][20][21]. The more thermodynamically stable silyl enol ether 13 was regioselectively formed from 12 under Holton’s conditions [22], and DDQ-mediated oxidation of 13 resulted in the formation of α,β-unsaturated ketone 14. Asymmetric reduction of ketone 14 was in turn realized by

Efficient synthesis of β’-amino-α,β-unsaturated ketones

• Isabelle Abrunhosa-Thomas,
• Aurélie Plas,
• Nishanth Kandepedu,
• Pierre Chalard and
• Yves Troin

Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52

• reaction of chiral imines with enolates derived from Weinreb amides [13][14]. In previous work on the asymmetric synthesis of 2,6-disubstituted piperidines by C–N bond formation, we demonstrated that intramolecular aza-Michael ”type” cyclisation [15] using a β'-carbamate-α,β-unsaturated ketone

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• catalyst [133]. The reaction yielded α,β-unsaturated ketone (E)-5b as a single isomer in ether solution, while a mixture of isomers 5b and 5d was obtained in THF solution (Scheme 46). They proposed that the reason for the selectivity would be attributed to intermediate 5c, which could stably exist in the

Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

• Matthias Leven,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2013, 9, 155–165, doi:10.3762/bjoc.9.18

• . α,β-Unsaturated ketone (0.14 mmol) was added subsequently, and the solution was stirred for 10 min at room temperature and cooled to the desired reaction temperature prior to the addition of 4-hydroxycoumarin. 4-Hydroxycumarin (0.1 mmol, 16 mg) was added, and the conversion was monitored by TLC. The

Features of the behavior of 4-amino-5-carboxamido-1,2,3-triazole in multicomponent heterocyclizations with carbonyl compounds

• Eugene S. Gladkov,
• Katerina A. Gura,
• Svetlana M. Sirko,
• Sergey M. Desenko,
• Ulrich Groth and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2012, 8, 2100–2105, doi:10.3762/bjoc.8.236

• lower than in the case of Methods A and B. Spirocompound 4c was obtained by linear reaction via preliminary synthesis and isolation of cyclic α,β-unsaturated ketone 5c and its further treatment with 4-amino-5-carboxamido-1,2,3-triazole (1) in acetic acid under ultrasonication at ambient temperature, in

Computational evidence for intramolecular hydrogen bonding and nonbonding X···O interactions in 2'-haloflavonols

• Tânia A. O. Fonseca,
• Matheus P. Freitas,
• Rodrigo A. Cormanich,
• Teodorico C. Ramalho,
• Cláudio F. Tormena and
• Roberto Rittner

Beilstein J. Org. Chem. 2012, 8, 112–117, doi:10.3762/bjoc.8.12

• strong resonant structure due to the C–X···O–C interaction in ortho position to a benzene ring conjugated with an α,β-unsaturated ketone is supposed to favour the C=X+ contribution and, therefore, to establish nonbonding C–X…O–C interactions, in addition to intramolecular HB, especially for the fluorine

Continuous-flow hydration–condensation reaction: Synthesis of α,β-unsaturated ketones from alkynes and aldehydes by using a heterogeneous solid acid catalyst

• Magnus Rueping,
• Teerawut Bootwicha,
• Hannah Baars and
• Erli Sugiono

Beilstein J. Org. Chem. 2011, 7, 1680–1687, doi:10.3762/bjoc.7.198

• reaction temperature and the flow rate are summarized in Table 1. Performing the reaction at 80 °C afforded the α,β-unsaturated ketone in 70% yield (Table 1, entry 5). Running the reaction at higher temperature (90 °C) showed a noticeable impact on the conversion and the product was isolated in 84% (Table

Efficient gold(I)/silver(I)-cocatalyzed cascade intermolecular N-Michael addition/intramolecular hydroalkylation of unactivated alkenes with α-ketones

• Ya-Ping Xiao,
• Xin-Yuan Liu and
• Chi-Ming Che

Beilstein J. Org. Chem. 2011, 7, 1100–1107, doi:10.3762/bjoc.7.126

• simple starting materials [41]. We initially envisioned that the gold(I)-catalyzed cascade process could be established starting from the intermolecular N-Michael reaction of α,β-unsaturated ketone 1 and substituted allylamine 2 to furnish an α-ketone intermediate I [42][43][44] (for gold-catalyzed

• the phenyl ring, with 2a under the optimized reaction conditions gave the expected product 3b in 92% yield, albeit with no diastereoselectivity (Table 3, entry 2). In addition to substrate 1b, α,β-unsaturated ketone 1c, with electron-withdrawing substituent on the phenyl ring, underwent this cascade

• reaction to afford the corresponding product 3c in 58% yield with a diastereomeric ratio of 1.7:1 (Table 3, entry 3). Reaction of alkyl α,β-unsaturated ketone 1d in the presence of 5 mol % of (t-Bu)2(o-biphenyl)PAuCl and 15 mol % of AgClO4 also gave the desired product 3d in 92% yield with a diastereomeric

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• very good example of this was published by Kalena et al. some years ago [87] who observed that 2-alkenyl-7-hydroxy-4-chromanone could undergo ortho photocycloaddition to afford the tetracyclic compounds shown in Scheme 28. The initial enol tautomerizes to the α,β-unsaturated ketone, which can be

Rh(I)-catalyzed intramolecular [2 + 2 + 1] cycloaddition of allenenes: Construction of bicyclo[4.3.0]nonenones with an angular methyl group and tricyclo[6.4.0.0^1,5]dodecenone

• Fuyuhiko Inagaki,
• Naoya Itoh,
• Yujiro Hayashi,
• Yumi Matsui and
• Chisato Mukai

Beilstein J. Org. Chem. 2011, 7, 404–409, doi:10.3762/bjoc.7.52

• ). Almost all of the reactions gave 2,6-dimethylbicyclo[4.3.0]non-1-en-8-one 8a, and the α,β-unsaturated ketone 9a could not be detected except for entry 9. This observation obviously differs from the PKTR products 2 and 5 having an electron withdrawing group instead of a methyl group (Scheme 1). We next

An expedient and new synthesis of pyrrolo[1,2-b]pyridazine derivatives

• Rajeshwar Reddy Sagyam,
• Ravinder Buchikonda,
• Jaya Prakash Pitta,
• Himabindu Vurimidi,
• Pratap Reddy Padi and
• Mahesh Reddy Ghanta

Beilstein J. Org. Chem. 2009, 5, No. 66, doi:10.3762/bjoc.5.66

• ; tertiary butyl carbamate; tertiary butyl carbazate; α,β-unsaturated ketone; Introduction Pyrrolopyridazine derivatives have various biological applications [1][2][3][4][5][6][7][8], and their fluorescent properties have been investigated for potential use in sensors, lasers, and semiconductor devices [9

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• synthesis of compound 22 began with double alkylation of (+)-21 through a cuprate conjugate addition followed by treatment of the resulting enolate with methyl iodide (Scheme 5). Retro-Diels-Alder reaction of 22 in refluxing 1,2-dichlorobenzene gave α,β-unsaturated ketone 23. Trisubstituted cyclopentanone

• NaBH4) of the nitrile, MOM protection of the newly formed primary alcohol, and hydrolysis of the dioxolane gave ketone 30 and occurred as a prelude to retro-Diels-Alder reaction of the latter, leading to the α,β-unsaturated ketone 31. Compound 32 was obtained by treatment with LDA and Mander’s reagent

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• from oxidation to the corresponding α,β-unsaturated ketone,[47] followed by conjugate addition. The dihydroxyation of the anti allylic alcohol 19 under Upjohn conditions was not synthetically useful (entry 8a, Table 1). Although dihydroxyation of the remote allyl group was rapid, the dihydroxylation of