- Conformation and Ortho steric effects in a series of 2-(pyrazol-l-yl)quinolines
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Nine 2-(pyrazol-l-yl)-4-methylquinolines bearing substituents on the pyrazole 3- or 5-positions (H, Me, Et, i-Pr, t-Bu) were regioselectively synthesized either using the direct condensation of 2-chloro-4-methylquinoline and sodium salt of 3(5)-substituted pyrazoles or by treatment of 2-hydrazino-4-methylquinoline with an appropriate β-ketoaldehyde. The 1H and 13C chemical shifts were discussed taking into account the preferred conformation about the C-2-N-1′ bond as calculated by the AM1 Hamiltonian. It appears that 5-ethyl and 5-isopropyl substituted derivatives present short C-H...N-1 interactions. Ortho steric effects appear to be responsible for these conformations.
- Singh, Shiv P.,Kumar, Dalip,Kumar, Devinder,Martinez, Ana,Elguero, Jose
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- Substrate range of the titanium TADDOLate catalyzed asymmetric fluorination of activated carbonyl compounds
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The substrate range of the [TiCl2(TADDOLate)] (TADDOL=α,α,α′,α′-tetraaryl-1,3-dioxolane-4, 5-dimethanol)-catalyzed asymmetric α-fluorination of activated β-carbonyl compounds has been investigated. Optimal conditions for catalysis are characterized by using 5 mol-% of TiCl2(naphthalen-1- yl)-TADDOLate) as catalyst in a saturated (0.14 mol/l) MeCN solution of F-TEDA (1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis- [tetrafluoroborate]) at room temperature. A series of α-methylated β-keto esters (3-oxobutanoates, 3-oxopentanoates) with bulky benzyl ester groups (60-90% ee) or phenyl ester (67-88% ee) have been fluorinated readily, whereas α-acyl lactones were also readily fluorinated, but gave lower inductions (13-46% ee). Double stereochemical differentiation in β-keto esters with chiral ester groups raised the stereoselectivity to a diastereomeric ratio (dr) of up to 96.5:3.5. For the first time, β-keto S-thioesters were asymmetrically fluorinated (62-91.5% ee) and chlorinated (83% ee). Lower inductions were observed in fluorinations of 1,3-diketones (up to 40% ee) and β-keto amides (up to 59% ee). General strategies for preparing activated β-carbonyl compounds as important model substrates for asymmetric catalytic α-functionalizations are presented (>60 examples). Copyright
- Bertogg, Andreas,Hintermann, Lukas,Huber, Dominique P.,Perseghini, Mauro,Sanna, Maria,Togni, Antonio
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experimental part
p. 353 - 403
(2012/05/07)
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- Microwave-assisted synthesis of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds to acetylene derivatives
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Microwave-assisted preparation of a wide range of 5-ethoxycarbonylpyrazoles and 3-pyrazoles by 1,3-dipolar cycloaddition of diazo compound to acetylenes is described. All reactions were carried out using high throughput sequential technique.{A figure is p
- Zrinski, Irena,Juribasic, Marina,Eckert-Maksic, Mirjana
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p. 1961 - 1967
(2007/10/03)
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- MALONONITRILE COMPOUND AND USE THEREOF
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A nitrile compound shown by the formula (1) has an excel lent pesticidal activity and it is useful as an active ingredient of pesticide.
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Page/Page column 42-43
(2008/06/13)
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- 1,2-AZOLE DERIVATIVES WITH HYPOGLYCEMIC AND HYPOLIPIDEMIC ACTIVITY
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A compound represented by the formula (1) wherein ring A is a ring optionally having 1 to 3 substituents; ring B is a 1,2-azole ring which may further have 1 to 3 substituents; Xa, Xb and Xc are the same or different and each is a bond, - O -, - S - and the like; Ya is a divalent aliphatic hydrocarbon residue having 1 to 20 carbon atoms; Yb and Yc are the same or different and each is a bond or a divalent aliphatic hydrocarbon residue having 1 to 20 carbon atoms; ring C is a monocyclic aromatic ring which may further have 1 to 3 substituents; and R represents -OR4 (R4 is hydrogen atom or optionally substituted hydrocarbon group) and the like, or a salt thereof or a prodrug thereof is useful as an agent for the prophylaxis or treatment of diabetes and the like.
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- On the Reactivity of N-Benzylpyrimidinium Salts with Nitrogen Nucleophiles (1,2)
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Treatment of the 1-benzyl salts of pyrimidine, 4,6-dimethylpyrimidine, and 4-t-butylpyrimidine with liquid ammonia leads to debenzylation.The 1H-nmr spectroscopic evidence is presented that the initial step in the debenzylation of 1-benzyl-4,6-dimethylpyrimidinium bromide is the addition of the ammonia at C-2, while with 1-benzyl-4-t-butylpyrimidinium bromide the addition takes place at C-6.It is proved by 15N labelling that the debenzylation occurs according to the ANRORC mechanism.The above-mentioned 1-benzylpyrimidinium bromides give with hydrazine, pyrazole, 3,5-dimethylpyrazole and 3-t-butylpyrazole, respectively.
- Dlugosz, A.,van der Plas, H.C.,van Veldhuizen, A.
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p. 373 - 375
(2007/10/02)
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