- Radical dehydroxylative alkylation of tertiary alcohols by Ti catalysis
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Deoxygenative radical C?C bond-forming reactions of alcohols are a long-standing challenge in synthetic chemistry, and the current methods rely on multistep procedures. Herein, we report a direct dehydroxylative radical alkylation reaction of tertiary alcohols. This new protocol shows the feasibility of generating tertiary carbon radicals from alcohols and offers an approach for the facile and precise construction of all-carbon quaternary centers. The reaction proceeds with a broad substrate scope of alcohols and activated alkenes. It can tolerate a wide range of electrophilic coupling partners, including allylic carboxylates, aryl and vinyl electrophiles, and primary alkyl chlorides/bromides, making the method complementary to the cross-coupling procedures. The method is highly selective for the alkylation of tertiary alcohols, leaving secondary/primary alcohols (benzyl alcohols included) and phenols intact. The synthetic utility of the method is highlighted by its 10-g-scale reaction and the late-stage modification of complex molecules. A combination of experiments and density functional theory calculations establishes a plausible mechanism implicating a tertiary carbon radical generated via Ti-catalyzed homolysis of the C?OH bond.
- Xie, Hao,Guo, Jiandong,Wang, Yu-Quan,Wang, Ke,Guo, Peng,Su, Pei-Feng,Wang, Xiaotai,Shu, Xing-Zhong
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supporting information
p. 16787 - 16794
(2020/11/09)
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- Total syntheses of surinone B, alatanones A–B, and trineurone A
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The total syntheses of four polyketides, surinone B (1), alatanones A–B (2–3), and trineurone A (4) were accomplished through an efficient and unified strategy via one-pot C-acylation reaction coupling 1,3-cyclohexadiones with EDC-activated acids under mild conditions. Alatanone A (2) was found to be a potent anti-microbial agent against Gram-positive and Gram-negative bacteria with MIC 31.25?μg/ml while alatanone B (3) was found to be a potent anti-fungal agent against Cladosporium cladosporioides with MIC 62.5?μg/ml compared to cycloheximide MIC 125?μg/ml. Our methodology allows performing kilogram scale of these scarce polyketides for the development of new antimicrobials.
- Gundoju, Narayana Rao,Bokam, Ramesh,Yalavarthi, Nageswara Rao,Buddana, Sudheer Kumar,Prakasham,Ponnapalli, Mangala Gowri
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- Modular synthesis and biological investigation of 5-hydroxymethyl dibenzyl butyrolactones and related lignans
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Dibenzyl butyrolactone lignans are well known for their excellent biological properties, particularly for their notable anti-proliferative activities. Herein we report a novel, efficient, convergent synthesis of dibenzyl butyrolactone lignans utilizing the acyl-Claisen rearrangement to stereoselectively prepare a key intermediate. The reported synthetic route enables the modification of these lignans to give rise to 5-hydroxymethyl derivatives of these lignans. The biological activities of these analogues were assessed, with derivatives showing an excellent cytotoxic profile which resulted in programmed cell death of Jurkat T-leukemia cells with less than 2% of the incubated cells entering a necrotic cell death pathway.
- Davidson, Samuel J.,Pilkington, Lisa I.,Dempsey-Hibbert, Nina C.,El-Mohtadi, Mohamed,Tang, Shiying,Wainwright, Thomas,Whitehead, Kathryn A.,Barker, David
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- Total synthesis of (-)-bicubebin A, B, (+)-bicubebin C and structural reassignment of (-)-cis-cubebin
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The first total synthesis of (-)-bicubebin A, and two previously unreported dilignans, (-)-bicubebin B and (+)-bicubebin C has been achieved through the dimerization of (-)-cubebin, confirming the structure and absolute stereochemistry of (-)-bicubebin A. Analysis of the data for (-)-bicubebin B showed it matched that of reported compound (-)-cis-cubebin. The NMR data of the subsequently synthesized proposed structure of cis-cubebin confirmed that its original proposed structure was incorrect.
- Davidson, Samuel J.,Pearce, A. Norrie,Copp, Brent R.,Barker, David
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p. 5368 - 5371
(2017/11/06)
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- A General and mild catalytic α-alkylation of unactivated esters using Alcohols
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Catalytic α-alkylation of esters with primary alcohols is a desirable process because it uses low-toxicity agents and generates water as the by-product. Reported herein is a NCP pincer/Ir catalyst which is highly efficient for α-alkylation of a broad scope of unactivated esters under mild reaction conditions. For the first time, alcohols alkylate unactivated α-substituted acyclic esters, lactones, and even methyl and ethyl acetates. This method can be applied to the synthesis of carboxylic acid derivatives with diverse structures and functional groups, some of which would be impossible to access by conventional enolate alkylations with alkyl halides. In a pinch: An NCP pincer/iridium catalyst is highly efficient for the α-alkylation of unactivated esters using alcohol under mild reaction conditions. The reaction is simple, clean, and scalable (1-10 mmol), and the scope with respect to the ester is wide.
- Guo, Le,Ma, Xiaochen,Fang, Huaquan,Jia, Xiangqing,Huang, Zheng
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supporting information
p. 4023 - 4027
(2015/03/30)
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- SULFONAMIDE CONTAINING COMPOUNDS AND USES THEREOF
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Compounds that modulate GHS-R are described herein.
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Page/Page column 55-56
(2010/10/03)
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- C-C bond formation from alcohols and malonate half esters using borrowing hydrogen methodology
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Alcohols have been used as alkylating agents in a decarboxylative reaction with malonate half esters via a borrowing hydrogen pathway catalysed by readily available Ru(PPh3)3Cl2.
- Pridmore, Simon J.,Williams, Jonathan M.J.
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scheme or table
p. 7413 - 7415
(2009/05/11)
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- INDUCIBLE NITRIC OXIDE SYNTHASE DIMERIZATION INHIBITORS
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The present invention relates to compounds and methods useful as inhibitors of nitric oxide synthase. Certain compounds of the subject invention have the following structural formula: wherein T, X, and Y are independently selected from the group consisting of CR4, N, NR4, S, and O; U is selected from the group consisting of CR10 and N; V is selected from the group consisting of CR4 and N; W and W' are independently selected from the group consisting of CH2, CR7R8, NR9, O, N(O), S(O)q and C(O); n, m and p are independently an integer from 0 to 5; q is 0, 1, or 2; and other substituents are as defined herein. Other compounds of the subject invention have structural formulas as defined herein. Also disclosed herein are pharmaceutical compositions comprising the compounds of the subject invention
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Page/Page column 58
(2010/11/08)
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- PROCESS FOR PRODUCING OPTICALLY ACTIVE 3-HYDROXYPROPIONIC ESTER DERIVATIVE
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The present invention is to provide a process for simply producing an optically active 3-hydroxypropionic ester derivative useful as a medicament intermediate from an inexpensive material. More specifically, the present invention is directed to a process for producing an optically active 3-hydroxypropionic ester derivative comprising reacting an acetic ester derivative available at low cost with a base and a formic ester, thereby converting the acetic ester derivative into a 2-formylacetic ester derivative, and thereafter, stereospecifically reducing the formyl group of the derivative by use of an enzymatic source capable of stereoselectively reducing the formyl group of the derivative.
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Page/Page column 9
(2010/02/13)
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- Substituted benzo[i]phenanthridines as mammalian topoisomerase-targeting agents
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Several benzo[c]phenanthridine and protoberberine alkaloids, such as nitidine and berberrubine, are known to induce DNA cleavage in the presence of either topoisomerase I or II. Structure-activity studies performed on various analogues related to benzo[c]phenanthridine and protoberberine alkaloids have provided insights into structural features that influence this topoisomerase-targeting activity. Modifications within the A-ring of benzo[c]phenanthridine and protoberberine alkaloids can significantly alter their ability to enhance the cleavable complex formation that occurs between DNA and topoisomerases. Select benzo[i]phenanthridines were synthesized as potential bioisosteres of nitidine and its analogues. In the present study, 2,3-methylenedioxy-8,9-dimethoxybenzo[i]phenanthridine, 2,3-methylenedioxy-8,9-dimethoxy-5-methylbenzo[i]phenanthridine, 2,3,8,9-tetramethoxybenzo[i]phenanthridine and 5-methyl-2,3,8,9-tetramethoxybenzo[i]phenanthridine were synthesized. These benzo[i]phenanthridine derivatives were evaluated for their ability to enhance cleavable complex formation in the presence of topoisomerases and DNA as well as for their cytotoxicity against the human lymphoblastoma cell line, RPMI8402. 2,3-Methylenedioxy-8,9-dimethoxybenzo[i]phenanthridine (4a) and its 5-methyl derivative (4b) are active as topoisomerase I-targeting agents. In contrast to nitidine, the presence of the 5-methyl substituent in the case of 4b is not associated with enhanced activity. Consistent with previous structure-activity studies on nitidine and protoberberine alkaloids, 2,3,8,9-teramethoxybenzo[i]phenanthridine, 5a, and its 5-methyl derivative, 5b, are inactive as topoisomerase I-targeting agents. These studies were extended to an evaluation of the relative pharmacological activities of 2,8,9-trimethoxybenzo[i]phenanthridine, 3,8,9-trimethoxybenzo[i]phenanthridine, and 2,3-methylenedioxy-8,9-methylenedioxybenzo[i]phenanthridine.
- Makhey, Darshan,Li, Dajie,Zhao, Baoping,Sim, Sai-Peng,Li, Tsai-Kun,Liu, Angela,Liu, Leroy F.,LaVoie, Edmond J.
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p. 1809 - 1820
(2007/10/03)
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- Inhibition of uridine phosphorylase: Synthesis and structure-activity relationships of aryl-substituted 5-benzyluracils and 1-[(2- hydroxyethoxy)methyl]-5-benzyluracils
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A series of 1-[(2-hydroxyethoxy)methyl]-5-benzyluracils were synthesized and tested for inhibition of murine liver uridine phosphorylase (UrdPase). Inhibitors of UrdPase are reported to enhance the chemotherapeutic utility of 5-fluoro-2'-deoxyuridine and 5-fluorouracil and to ameliorate zidovudine- induced anemia in animal models. We prepared a series of 5-aryl-substituted analogues of 5-benzylacyclouridine (BAU), a good inhibitor of UrdPase (IC50 of 0.46 μM), to develop a compound with enhanced potency and improved pharmacokinetics. The first phase of structure-activity relationship studies on a series of 32 aryl-substituted 5-benzyluracils found several 5-(3- alkoxybenzyl) analogues of 5-benzyluracil with enhanced potency. The acyclovir side chain, the (2-hydroxyethoxy)methyl group, was substituted on the more potent aryl-substituted 5-benzyluracils. The two most potent compounds, 10y (3-propoxy) and 10dd (3-sec-butoxy), were inhibitors of UrdPase with IC50s of 0.047 and 0.027 μM, respectively. Six compounds were tested in vivo for effects on steady-state concentrations of circulating uridine in rats. Plasma uridine levels were elevated 3-9-fold by compound levels that ranged from 8 to 50 μM.
- Orr,Musso,Boswell,Kelley,Joyner,Davis,Baccanari
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p. 3850 - 3856
(2007/10/02)
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- Lewis acid-promoted alkylations of arenes and 1-trimethylsilylalkynes with β-chloro-β-thiopropanoic esters
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Ethyl 3-chloro-3-(3,4-dichlorophenylthio)propanoate (8) reacted with electron-rich arenes in the presence of titanium tetrachloride to give the Friedel-Crafts products 10a-13a. Reactions of 8 with 1-trimethylsilylalkynes 14a-d were effected with aluminum chloride to afford the substitution products 15a-d. Some chemical transformations of the products are also described.
- Ishibashi,Mino,Sakata,Inada,Ikeda
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p. 1148 - 1151
(2007/10/02)
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