Naphthalene-catalysed Lithiation of Chlorinated Nitrogenated Aromatic Heterocycles and Reaction with Electrophiles

l-Proline catalyzed one-pot synthesis of polysubstituted pyridine system incorporating benzothiazole moietyviasustainable sonochemical approach

The efficient, highly convenient synthesis of polysubstituted pyridine derivatives was established via the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamides with an assortment of arylidene malononitriles and arylidene ethyl cyanoacetates in the presence of l-proline as an efficient organocatalyst for this type of ultrasonic-mediated Michael addition. The mechanistic pathway and factors affecting this reaction were also established. The main characteristics of this procedure are high yields, use of a cost-effective catalyst, and easy work-up and purification.

The l-proline catalyzed ultrasonic-mediated synthesis of polysubstituted pyridone derivatives through the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamides with an assortment of arylidenes has demonstrated as an efficient protocol.

Synthesis and activity studies of analogues of the rat selective toxicant norbormide

Norbormide [5-(alpha-hydroxy-alpha-2-pyridylbenzyl)-7-(alpha-2-pyridylbenzylidene)-5-norbornene-2,3-dicarboximide] (NRB, 1), an existing but infrequently used rodenticide, is known to be uniquely toxic to rats but relatively harmless to other rodents and mammals. A series of NRB-related analogues were prepared to investigate the structural features responsible for, and the in vitro biological markers indicative of, in vivo lethality of the parent molecule in rats. Their synthesis and biological evaluation (vasoconstriction, vasodilation, mitochondrial dysfunction, cardiotoxicity and lethality) is described.

Highly functionalized organomagnesium reagents prepared through halogen-metal exchange

Organomagnesium reagents occupy a central position in synthetic organic and organometallic chemistry. Recently, the halogen-magnesium exchange has considerably extended the range of functionalized Grignard reagents available for synthetic purposes. Functional groups such as esters, nitriles, iodides, imines, or even nitro groups can be present in a wide range of aromatic and heterocyclic organomagnesium reagents. Also various highly functionalized alkenyl magnesium species can be prepared. These recent developments as well as new applications of organomagnesium reagents in cross-coupling reactions and amination reactions will be covered in this Review.

Preparation of nitrogen-containing pi-deficient heteroaromatic Grignard reagents: oxidative magnesiation of nitrogen-containing pi-deficient halogenoheteroaromatics using active magnesium

The oxidative magnesiation of nitrogen-containing pi-deficient halogenoheteroaromatics using active magnesium was accomplished. Both magnesiation followed by addition of a carbonyl compound (Grignard reaction) and magnesiation in the presence of a carbonyl compound (Barbier reaction) were carried out to afford the corresponding product. Especially, the latter method enabled fused halogenodiazines such as 4-chloro-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine or 2-chloroquinoxaline to magnesiate at a mild temperature (-20 to 30 degrees C).

Modification of the Atropisomeric N,N-Ligand 2,2'-Di(pyridin-2-yl)-1,1'-binaphthalene and Its Application to the Asymmetric Allylation of Benzaldehyde

The atropisomeric compound 2,2'-di(pyridin-2-yl)-1,1'-binaphthalene (1) has been chlorinated, via its bis-N-oxide 2, at the 4 and 6 pyridine ring positions so as to generate the three isomeric species: 2,2'-bis(6-chloropyridin-2-yl)- (3a), 2-(4-chloropyridin-2-yl)-2'-(6-chloropyridin-2-yl)- (3b) and 2,2'-bis(4-chloropyridin-2-yl)-1,1'-binaphthalene (3c). The dichlorinated compounds underwent Ni-catalysed Kumada cross-coupling with MeMgI to give the methylated pyridine isomers: 2,2'-bis(6-methylpyridin-2-yl)- (4a), 2-(4-methylpyridin-2-yl)-2'-(6-methylpyridin-2-yl)- (4b) and 2,2'-bis(4-methylpyridin-2-yl)-1,1'-binaphthalene (4c). The enantiomerically pure forms of the six novel ligands (3a-3c and 4a-4c), prepared from enantiomerically pure 2,2'-di(pyridin-2-yl)-1,1'-binaphthalene (1), were tested in asymmetric catalysis, but proved to be no better and in most cases poorer than parent 1. The coordination of the ligands to Zn and Pd fragments has been explored and compared with the parent compound 1 so as to rationalise the negative effect of pyridine substitution on asymmetric induction in the zinc-catalysed allylation of benzaldehyde.