[Reactions concerned in tertiary amine N-oxides. V. A new method for the preparation of asymmetric 2,2'-dipyridyl, 2,2'-pyridylquinoline and pyridylphenanthroline derivatives (author's transl)]

Heteroaryl cross-coupling as an entry toward the synthesis of lavendamycin analogues: a model study

ABC analogues of the antitumor antibiotic lavendamycin, which contain the key metal chelation site and redox-active quinone unit essential for biological activity, were prepared via the palladium(0)-catalyzed cross-coupling reaction of various 2-haloheteroaromatics with 2-stannylated pyridines and quinolines. Using the Stille reaction, 2-bromo substituted quinolines and 1-bromoisoquinolines were found to undergo efficient coupling with 2-pyridinylstannanes to provide unsymmetrical heterobiaryl derivatives. While the Stille reaction using the reverse coupling partners (i.e., 2-quinolinylstannanes and haloheteroaromatics) had not received much attention in the literature, we found that this alternative coupling reaction efficiently provided several new heterobiaryl derivatives. The gold-catalyzed intramolecular cycloisomerization of N-(prop-2-ynyl)-1H-indole-2-carboxamide smoothly afforded a beta-carbolinone derivative that was subsequently used for a Pd(0)-catalyzed cross-coupling directed toward the synthesis of lavendamycin analogues.

Functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines via stille-type cross-coupling procedures

Stille-type cross-coupling procedures are utilized in order to prepare a variety of functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines. Such N-heterocyclic compounds are of great interest as chelating ligands for transition-metal ions in the field of supramolecular chemistry. Various mono- and disubstitued 2,2'-bipyridines were synthesized in high yields and multigram scales using a modular design principle. The terpyridines may be functionalized in one step with different substituents at the outer pyridine rings and at the 4'-position of the centered ring, leading to multifunctionalized compounds. The initially obtained methyl ester and ethyl ester groups can be simply converted into bromomethyl and hydroxymethyl groups which allow further functionalization reactions.

Stille-type cross-coupling-An efficient way to various symmetrically and unsymmetrically substituted methyl-bipyridines: toward new ATRP catalysts

Various mono- and disubstituted 2,2'-bipyridines were synthesized in high yields and multigram scales utilizing Stille-type coupling procedures. The corresponding bromo-picoline and tributyltin-picoline building blocks were prepared from commercially available amino-picoline compounds. As first examples of metal complexes, 4,5'-dimethyl-2,2'-bipyridine was reacted with copper(II) and iron(II) ions and investigated as catalyst in ATRP.