- Metalation of 2-heterosubstituted naphthalenes at the 1- or 3- position: Factors that may determine the regiochemistry
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Upon metalation and subsequent electrophilic trapping, 2-fluoronaphthalene inevitably gives rise to regioisomeric mixtures in varying proportions, whereas 2-(trifluoromethyl)naphthalene undergoes deprotonation either at the 1- or the 3-position, depending on the choice of the reagent. On the other hand, 2-(trifluo-romethoxy)naphthalene and 2-methoxynaphthalene react exclusively at the 3-position when, respectively, sec-butylhthium and superbasic reagents are employed. Steric repulsion by the peri hydrogen in combination with crowding due to coordination of the lithium atom with the methoxy group disfavors attack at the 1-position. Georg Thieme Verlag Stuttgart.
- Ruzziconi, Renzo,Spizzichino, Sara,Giurg, Miroslav,Castagnetti, Eva,Schlosser, Manfred
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Read Online
- Decarbonylative halogenation by a vanadium complex
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Metal-catalyzed halogenation of the C-H bond and decarbonylation of aldehyde are conventionally done in nature. However, metal-mediated decarbonylative halogenation is unknown. We have developed the first metal-mediated decarbonylative halogenation reaction starting from the divanadium oxoperoxo complex K3V5+2(O 22-)4(O2-)2(μ-OH) (1). A concerted decarbonylative halogenation reaction was proposed based on experimental observations.
- Rana, Sujoy,Haque, Rameezul,Santosh, Ganji,Maiti, Debabrata
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p. 2927 - 2932
(2013/04/24)
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- Benzo[a]pyrano[3,2-h]acridin-7-one compounds
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A compound selected from those of formula (I): 1 wherein: X and Y represent a group selected from hydrogen, halogen, hydroxy, alkoxy, nitro, cyano, alkyl, trihaloalkyl and NRaRb, wherein Ra and Rb are as defined in the description R1 represents hydrogen or alkyl R2 represents a group selected from hydrogen, alkyl, —OR″a, —NR′aR′b, -Ta-O″a, —N″a-Ta-NR′aR′b, —N″a—C(O)-TaH, —O—C(O) TaH, Ta-NR′aR′b, —NR″a-Ta-OR″a, —NR″a-Ta-CO2R″a and —N″a—C(O)-Ta-NR′aR′b, wherein R′a, R″a, R′b and Ta are as defined in the description R3 and R4 represent hydrogen or alkyl A represents a group of formula —CH(R5)CH(R6), —CH=C(R7)—, —C(R7)=CH—, —C(O)CH(R8) or —CH(R8)—C(O), wherein R5, R6, R7 and R8 are as defined in the description its isomers, N-oxides, and addition salts thereof with a pharmaceutically acceptable acid or base, and medicinal products containing the same which are useful in the treatment of cancer.
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Page/Page column 18
(2010/02/10)
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- Barriers to rotation about the chiral axis of tertiary aromatic amides
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The barrier to rotation about the aryl-carbonyl bond in 40 tertiary aromatic amides was determined by variable temperature NMR spectroscopy (for rapid rotations) or by following the interconversion of atropisomers (for slower rotations). Empirical guidelines to the rate of Ar-CO bond rotation in hindered tertiary aromatic amides, and hence the stability of the atropisomeric stereoisomers of axially chiral amides, are presented.
- Ahmed, Anjum,Bragg, Ryan A.,Clayden, Jonathan,Lai, Lai Wah,McCarthy, Catherine,Pink, Jennifer H.,Westlund, Neil,Yasin, Samreen A.
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p. 13277 - 13294
(2007/10/03)
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- Manganese(III)-Mediated Formylation of Aromatic Compounds in the Presence of Malonic Acid
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The reaction of naphthlenes with malonic acid in the presence of manganese(III) acetate gives naphthalenecarbaldehydes and naphthalenecarboxylic acids.Similar reactions of anthracene, pyrene, and methoxybenzenes also yield formylated and carboxylated products.It was found that the formyl group introduced to the aromatic ring was not derived from carboxymethyl radical generated directly by the thermolysis of manganese(III) acetate, but from a dicarboxymethyl radical formed by the interaction of malonic acid and manganese(III) acetate.In addition, it was also found that the dicarboxymethyl radicals attacked the position of the highest electron density on the aromatic ring and that this formylation was effective when the ionization potential of the aromatic copound was lower than 7.8 eV.
- Nishino, Hiroshi,Tsunoda, Katsunori,Kurosawa, Kazu
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p. 545 - 550
(2007/10/02)
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