ABNORMAL NUCLEOPHILIC SUBSTITUTION OF 3-TRICHLOROMETHYLPYRIDINES BY METHOXIDE
3-Trichloromethylpyridine and its α-chlorinated derivatives behave as ambident electrophilic substrates towards methoxide which attacks an α-position and the trichloromethyl group.
Dainter, Ronald S.,Suschitzky, Hans,Wakefield, Basil J.,Hughes, Nigel,Nelson, Anthony J.
Multiple Paths for Photo-alkylation and -alkoxylation of 3-Pyridinecarboxylic Ester in Alcohol. Simultaneous Contribution of Several Kinds of Excited States
UV-irradiation of methyl 3-pyridinecarboxylate (1) in acidic alcoholic solutions brings about the alkoxylation and alkylation at the pyridine ring.Photoalkylation occurs in several paths: 1) alkylation initiated by the triplet ?-?* state, 2) alkylation initiated by the triplet n-?* state of the carbonyl moiety of the ester group, 3) alkylation initiated by exciplex between a free base form of 1 and a pyridinium form of 1, and 4) alkylation promoted by chloride ions.Photoalkoxylation originates from a singlet excited state of 1.In the photoreactions of 1 in strongly a cidic methanolic solutions acidified with H2SO4, three kinds of excited states (two kinds of triplet states for alkylation and a singlet state for alkoxylation) contribute simultaneously.
Sugimori, Akira,Tobita, Etsuo,Kumagai, Yasuyuki,Sato, Gen P.
Nickel-catalyzed carboxylation of aryl and heteroaryl fluorosulfates using carbon dioxide
The development of efficient and practical methods to construct carboxylic acids using CO2 as a C1 synthon is of great importance. Nickel-catalyzed carboxylation of aryl fluorosulfates and heteroaryl fluorosulfates with CO2 is described, affording arene carboxylic acids with good to excellent yields under mild conditions. In addition, a one-pot phenol fluorosulfation/carboxylation is developed.
Transformations of trichloromethyl groups during reactions of 3-trichloromethylpyridines with methoxide
When methoxide ion attacks an unsubstituted 2- or 6-position of a 3-trichloromethylpyridine, a hydrogen shift leads to a methoxy-substituted 3-dichloromethylpyridine. Further reaction of the dichloromethyl group with methoxide gives the corresponding acetal. This type of reaction has been applied to several chlorinated 3-trichloromethylpyridines and to 3- trichloromethylpyridine itself; a convenient synthesis of the latter is described.
Dainter, Ronald S.,Jackson, Tracey,Omar, Abdirahman H. H.,Suschitzky, Hans,Wakefield, Basil J.,Hughes, Nigel,Nelson, Anthony J.,Varvounis, George
p. 283 - 287
(2007/10/02)
MULTIPLE PATHS FOR PHOTOALKYLATION OF PYRIDINECARBOXYLIC ESTERS IN ALCOHOLS
Photochemical substitution of ring hydrogen of pyridinecarboxylic esters by alkyl groups derived from solvent alcohols occurs in several paths: 1) alkylation initiated by excited carbonyl moiety of the ester group and 2) alkylation initiated by the excitation of the ?-electronic system of the pyridine ring.In the photoreaction of methyl 3-pyridinecarboxylate in acidic methanol, three types of excited state (two triplet states for alkylation and a singlet state for alkoxylation) contribute simultaneously.