- Synthesis of 7-hydroxyspiropyran
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The 7-acetoxyspiropyrans (4a and 4b) have been prepared by the reaction of Fischer's bases (3) with 2,4-diacetoxybenzaldehyde in refluxing ethanol in moderate yields. The acetyl group of 7-acetoxyspiropyran 4a was easily removed to give a 7-hydroxyspiropy
- Cho, Young Jin,Lee, Seung Hwan,Bae, Jong Woo,Kim, Sung Hoon,Keum, Sam Rok,Yoon, Cheol Min
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- The studies on chemoselective promiscuous activity of hydrolases on acylals transformations
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Chemoselective, mild and convenient protocol for the hydrolysis of the synthetically relevant acylals via promiscuous enzyme-catalyzed hydrolysis has been developed. It has been shown that promiscuous activity of the used hydrolases dominates their native activity related with carboxylic esters hydrolysis. The main advantage of the present methodology is that it can be conducted under neutral conditions at room temperature. Moreover, complete deprotection of acylals takes place within 10–20 min. Developed protocol can be used with compounds having a variety of hydrolytic labile groups since the cleavage is proceeded under neutral conditions and occurs exclusively on acylal moiety. Further this protocol was extended by the tandem Passerini multicomponent reaction leading to the α-acetoxy amides using acylals as the surrogates of the carbonyl components to P-MCR.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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- Functional group manoeuvring for tuning stability and reactivity: Synthesis of cicerfuran, moracins (D, E, M) and chromene-fused benzofuran-based natural products
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The protecting group manoeuvring as a strategy was applied for tuning the stability and reactivity of 4-(2,2-dibromovinyl)benzene-1,3-diol (12a) and 6-(2,2-dibromovinyl)-2,2-dimethylchroman-7-ol (22) in the domino synthesis of benzofuran-based natural products (1-8). The functional group demands and their impact on the reactivity driven by electronic effects were successfully managed by varying the protecting groups with substituted gem-dibromovinylphenols in domino couplings and triarylbismuth reagents under palladium-catalyzed conditions. This approach paved the way for the synthesis of moracin M (1) and cicerfuran (2), and the first time synthesis of moracin D (3) and moracin E (4) along with chromene-fused benzofuran-based natural products (5-8) in overall good yields.
- Rao, Maddali L. N.,Murty, Venneti N.,Nand, Sachchida
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p. 9415 - 9423
(2017/11/23)
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- Molecular modeling and snake venom phospholipase A2 inhibition by phenolic compounds: Structure-activity relationship
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In our earlier study, we have reported that a phenolic compound 2-hydroxy-4-methoxybenzaldehyde from Janakia arayalpatra root extract was active against Viper and Cobra envenomations. Based on the structure of this natural product, libraries of synthetic structurally variant phenolic compounds were studied through molecular docking on the venom protein. To validate the activity of eight selected compounds, we have tested them in in vivo and in vitro models. The compound 21 (2-hydroxy-3-methoxy benzaldehyde), 22 (2-hydroxy-4-methoxybenzaldehyde) and 35 (2-hydroxy-3-methoxybenzylalcohol) were found to be active against venom-induced pathophysiological changes. The compounds 20, 15 and 35 displayed maximum anti-hemorrhagic, anti-lethal and PLA2 inhibitory activity respectively. In terms of SAR, the presence of a formyl group in conjunction with a phenolic group was seen as a significant contributor towards increasing the antivenom activity. The above observations confirmed the anti-venom activity of the phenolic compounds which needs to be further investigated for the development of new anti-snake venom leads.
- Alam, Md. Iqbal,Alam, Mohammed A.,Alam, Ozair,Nargotra, Amit,Taneja, Subhash Chandra,Koul, Surrinder
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p. 209 - 219
(2016/03/22)
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- Benzofuran derivatives as anticancer inhibitors of mTOR signaling
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A series of 32 derivatives and isosteres of the mTOR inhibitor 2 were synthesized and compared for their cytotoxicity in radioresistant SQ20B cancer cell line. Several of these compounds, in particular 30b, were significantly more cytotoxic than 2. Importantly, 30b was shown to block both mTORC1 and Akt signaling, suggesting insensitivity to the resistance associated to Akt overactivation observed with rapamycin derivatives currently used in clinic.
- Salomé, Christophe,Ribeiro, Nigel,Chavagnan, Thierry,Thuaud, Frédéric,Serova, Maria,De Gramont, Armand,Faivre, Sandrine,Raymond, Eric,Désaubry, Laurent
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supporting information
p. 181 - 191
(2014/06/09)
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- Expeditious synthesis of the aromatic spiroketal skeleton using hetero-Diels-Alder cycloaddition
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The hetero-Diels-Alder reactions of enolic ethers generated from methylenation of various esters are described, which allow for the rapid synthesis of various substituted [6,6] aromatic spiroketal skeletons.
- Zhou, Guanglian,Zheng, Deping,Da, Shijun,Xie, Zhixiang,Li, Ying
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p. 3349 - 3352
(2007/10/03)
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- Total synthesis of moracin C
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Moracin C has been synthesised by the most efficient route to date (10 steps and 12% overall yield). The relatively unexplored acid-induced, intramolecular migration of an acyl group from an ortho phenolic hydroxy to a benzylic hydroxy is used to synthesise o-hydroxybenzylphosphonium salts containing ester groups. The phosphonium salts are coupled with 3,5-dimethoxybenzoic acid. Intramolecular Wittig reaction then gives 2-arylbenzo[b]furans, bearing the key 1′,3′,5′ substitution pattern on the aryl ring. This discovery provides a concise route to polyphenolic benzo[b]furans that we expect to be of general utility.
- McAllister, Graeme D.,Hartley, Richard C.,Dawson, Michael J.,Knaggs, Andrew R.
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p. 3453 - 3457
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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- Synthesis of a Proposed Isomer of F420 having α-Glutamyl Bonding.
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A proposed isomer of redox coenzyme F420 having α-glutamyl bonding, has been synthesized from 8-benzyloxy-10-D-ribityl-5-deazaflavin and α-L-glutamyl-L-glutamic acid moiety, by the phosphite triester approach followed by deprotection procedures.
- Kimachi, Tetsutaro,Tanaka, Kiyoshi,Yoneda, Fumio
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p. 439 - 443
(2007/10/02)
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- Ortho Effect in the Fragmentation of 2-Acetoxychalcones under Electron Impact
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2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions.The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond.The intense flavylium ion originates as shown by specific labelling with 18O-from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar-O bond and (b) sequential elimination of ketene and a hydroxy radical.
- Mentlein, Rolf,Vowinkel, Erich
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p. 330 - 333
(2007/10/02)
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