A. Godard

Connection between metalation and cross-coupling strategies. A new convergent route to azacarbazoles

Abstract New convergent synthesis of azacarbazoles through metalation, cross-coupling reaction and intramolecular substitution via (2-aminobenzene)boronic acid and ortho-fluoroiodopyridines.

Metallation of pyridine N-oxides and application to synthesis

Regio- and chemi-selective, directed ortho-lithiation of 2-, 2,5- or 3,4-substituted pyridine N-oxides has been achieved with diisopropylamide and butyllithium. Polysubstituted pyridine N-oxides, azaxanthone, and an isomer of orelline have been synthesized by such methods.

Directed lithiation of unprotected pyridinecarboxylic acids: syntheses of halo derivatives

Deprotonation of all isomeric lithium pyridinecarboxylates and subsequent trapping with hexachloroethane or iodine afforded straightforward access to chloro- and iodopyridinecarboxylic acids, respectively. Starting from lithium 5-bromonicotinate, the introduction of an iodine atom at C4 and further halogen migration allowed the potential of this method to be extended to the synthesis of more elaborate derivatives.

Synthesis of 4,5-Disubstituted Benzo[c][2,7]naphthyridines by Combined Metalation-Palladium-Catalysed Cross-Coupling Strategies. Preparation of 8h-Pyrido[4,3,2-mn]acridone as a Model of Cystodytin Alkaloids

Abstract A short and efficient synthesis of 8H-pyrido[4,3,2-mn]acridone is described. The strategy involves the preparation of 4-chloro-5-methylbenzo[c][2,7]naphtyridine, as key intermediate, by metalation and Palladium catalyzed cross-coupling reaction. A second cross-coupling reaction and subsequent oxydation by SeO2 led to the title compound.

Nucleophilic addition of lithio derivatives to 1-substituted benzo[c][2,7]naphthyridines (2,9-diazaphenanthrenes)

Nucleophilic addition of lithio derivatives to 1-substituted benzo[c][2,7]naphthyridines and rearomatization of the intermediate dihydro compounds with MnO2 gives good overall yields of product.

Perkin communications. Synthesis of 3-amino-4-phenylpyridines: a novel strategy for the preparation of CD ring models of streptonigrin

An efficient synthesis of 3-amino-4-phenylpyridine derivatives is reported. 3-Pivaloylaminopyridines were lithiated by butyl-lithium before reaction with iodine as electrophile to afford 4-iodo-3-pivaloylaminopyridines. Cross-coupling of the latter with suitable phenylboronic acids gives CD ring models of streptonigrin.

SYNTHESIS OF NEW SUBSTITUTED QUINOLIZIDINES AS POTENTIAL INHIBITORS OF ERGOSTEROL BIOSYNTHESIS

Abstract Carbocationic species (High Energy Intermediates) have been postulated as intermediates in the course of enzymatic synthesis of ergosterol. Protonated aza-analogues of the sterol are thus potential inhibitors. The synthesis of substituted quinolizidines ( 3 ) is reported. 4-Methoxy-2,3-dimethylpyridine ( 4 ) was metalated and reacted with substituted 3-chloropropanal to build the 1-methyl-2-quinolizidinone. The lateral chain was prepared via a Wittig-Horner reaction.

Quaternization at the picolinic carbon. Application to the synthesis of pyridylalkanecarboxylic acids

The paper describes two different methodologies for the construction of a quaternary center at the picolinic site, and their application to the synthesis of pyridylalkanecarboxylic acids. The first one involves a one-pot acetylation–Michael addition procedure followed by an alkylative quaternization of the picolinic carbon. The second one is based on the deprotonation at the picolinic carbon of 2-(α,α-dialkyl)pyridines using the superbasic mixture BuLi–diisopropylamine–ButOK (“KDA”). Both routes give very good yields.