Search

Cross-coupling reactions of biphenyl compounds that were investigated and still-growing number of efficient catalysts with various ligands that were available for the transformations is discussed. It was seen that the Stille coupling was superior to the other methods and enabled the synthesis of the title compounds with diverse connectivity.

A novel, short and efficient synthetic pathway to 3-{4-[2-(3-chlorophenylamino)-pyrimidine-4-yl]-pyridin-2-ylamino}-propanol and a series of analogues is developed. The synthetic sequence consisted of a Negishi-type cross-coupling reaction in the key step followed by two subsequent nucleophilic substitution reactions.

The synthesis of a class of benzothiazole derivatives selectively functionalized at 7-position involves direct lithiation of 2,2-dimethyl-N-(3-halophenyl)propanethioamides or N-(3-halophenyl)propane thioamides. The lithium attack occurs at 2-position because of the ortho directing effect of halogen. This is followed by cyclization of the aryne intermediate and quenching of the resulting aryllithium with selected electrophiles.

A lithiation method was modified to investigate the effects of lithiation temperature, concentration, lithiating agent and solvent in the reaction of phenylcarbamic acid 1,1-dimethylethyl ester (N-boc-aniline). Lithiation was analyzed on BuLi solutions in diethyl ether and THF at different temperatures. The use of electrophiles Me2S2, CICONEt2, t-BuN=C=O and CICON(Me)CH2Ph(4-t-Bu) showed influence on the product yields.

An investigation was carried out on the halogen dance (HD) on various 2-thiazolamine systems thus providing an easy access to a series of 5-substituted 4-bromo-2-thiazolamine derivatives. HD was found be a favored process for the investigated systems and the prevention of HD is only possible when optimized reaction conditions and selected electrophiles are applied.

The half-lives of organolithium reagents were analyzed based on a modified titration technique that utilizes sec-butanol in toluene with 1,10-phenamthroline as a chemical indicator. Analysis of the pseudo-first-order kinetics of organolithium reagents indicated the presence of arrested decomposition in some reagents due to a stable donor-acceptor complex. On the other hand, an accelerating rate of decomposition was detected in tetrahydropyran and t-BuLi due to ring-opening reactions.