- Synthesis of Acyclic Aliphatic Amides with Contiguous Stereogenic Centers via Palladium-Catalyzed Enantio-, Chemo- and Diastereoselective Methylene C(sp3)?H arylation
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The enantioselective desymmetrizing C?H activation of α-gem-dialkyl acyclic amides remains challenging because the availability of four chemically identical unbiased methylene C(sp3)?H bonds and increased rotational freedoms of the acyclic systems add tremendous difficulties for chemo- and stereocontrol. We have developed a method for the synthesis of acyclic aliphatic amides with α,β-contiguous stereogenic centers via PdII-catalyzed asymmetric arylation of unbiased methylene C(sp3)?H, in good yields and with high levels of enantio-, chemo- and diastereoselectivity (up to >99 % ee and >20:1 d.r.). Successive application of this method enables the sequential arylation of the gem-dialkyl groups with two different aryl iodides, giving a range of β-Ar1-β′-Ar2-aliphatic acyclic amides containing three contiguous stereogenic centers with excellent diastereoselectivity.
- Deng, Yao-Ting,Ding, Yi,Han, Ye-Qiang,Kong, Ke-Xin,Shi, Bing-Feng,Wu, Le-Song,Yang, Xu
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supporting information
p. 20455 - 20458
(2020/09/07)
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- Pd-Catalyzed debenzylation and deallylation of ethers and esters with sodium hydride
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Herein we demonstrate simply that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant. The reactivity is engineered into a palladium-catalyzed reductive debenzylation and deallylation of aryl ethers and esters. This operationally simple, mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance (>50 examples) and high chemoselectivity toward aryl ethers over aliphatic structures. Moreover, the dual reactivity of NaH as a base and a reductant is demonstrated in efficient synthetic elaboration.
- Mao, Yujian,Liu, Ye,Hu, Yanwei,Wang, Liang,Zhang, Shilei,Wang, Wei
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p. 3016 - 3020
(2018/04/14)
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- Use of ethyl (benzothiazol-2-ylsulfonyl)acetate for malonic ester-type syntheses of carboxylic acids and esters
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A new methodology for the synthesis of substituted carboxylic acids is described. Alkylation of either ethyl (benzothiazol-2-ylsulfonyl)acetate or ethyl 2-(benzothiazol-2-ylsulfonyl)propionate was achieved with alkyl halides and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane solution. These products were then desulfinated and hydrolysed in one-pot under mild conditions to give substituted acetic acids in good-to-excellent yields.
- Hussein, Waleed M.,McGeary, Ross P.
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p. 1222 - 1227
(2014/10/16)
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- A flavin analogue with improved solubility in organic solvents
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We report the synthesis and initial electrochemical characterization of a benzene-soluble flavin analogue: N(10)-2,2-dibenzylethyl-7,8-dimethylisoalloxazine (DBF, 1). This analogue, which has an unmodified flavin headgroup, is intended for use in the spectroscopic examination of the electronic effects of flavin hydrogen bonding in simple model systems in aprotic, non-hydrogen bonding solvents. With future spectroscopic studies in mind, we have developed a synthetic route, which allows the incorporation of isotopic labels using inexpensive starting materials.
- Koder, Ronald L.,Lichtenstein, Bruce R.,Cerda, Jose F.,Miller, Anne-Frances,Dutton, P. Leslie
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p. 5517 - 5520
(2008/02/13)
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- Microwave assisted hydrolysis of Meldrum's acid derivatives and decarboxylation of derived malonic acids
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Microwave induced hydrolysis of alkyl Medrum's acids and decarboxylation of derived malonic acids using poly-4-vinylpyridine as a catalyst gives high yields of carboxylic acids in a short time.
- Helavi,Solabannavar,Desai,Mane
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p. 174 - 175
(2007/10/03)
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- Selective Activation of Primary Carboxylic Acids by Electron-rich Triarylbismuthanes. Application to Amide and Ester Synthesis under Neutral Conditions
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On being heated in benzene in the presence of tris(methoxyphenyl)bismuthanes 1b-1e, primary carboxylic acids are selectively activated to couple with amines and alcohols to produce the corresponding amides and esters in satisfactory yields, while secondary, tertiary and aromatic carboxylic acids remain unaffected. 2-Benzylmalonic acid is similarly converted into its corresponding diamides and diesters, but 2,2-dibenzylmalonic acid suffers extensive decarboxylation and, in the presence of aromatic olefins, it undergoes a novel -type cycloaddition reaction to form 4-substituted 2,2-dibenzyl-4-butanolides in low to fair yields.
- Ogawa, Takuji,Hikasa, Tetsuya,Ikegami, Tohru,Ono, Noboru,Suzuki, Hitomi
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p. 3473 - 3478
(2007/10/02)
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- Dipeptides as renin inhibitors
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Dipeptides are described which are represented by the formula STR1 wherein the various substituents are defined hereinbelow. These compounds have a strong inhibitory efect on human renin, and are useful as a therapeutically active agent for the treatment of hypertension, especially renin-associated hypertension.
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