David Nečas

Nickel-catalyzed cyclization of α,ω-dienes: formation vs. cleavage of C–C bonds

A combination of a catalytic amount of a Ni–phosphine complex and triethylaluminium or chlorodiethylaluminium is able to selectively cyclize a number of 1,7-heptadienes to methylidene(methyl)cyclopentanes and cyclopentenes even in cases where the dienes are prone to deallylation.

Modular synthesis of 1-α- and 1-β-(indol-2-yl)-2′-deoxyribose C-nucleosides

A simple two-step method for the selective preparation of anomerically pure 1α- and 1β-(indol-2-yl)deoxyribose derivatives was developed. The synthesis was based on the Sonogashira reaction of 1α- and 1β-ethynyldeoxyribose and 2-haloanilines followed by a Pd-complex catalyzed cyclization to the corresponding indolyldeoxyribosides.

Direct regioselective C–H borylation of [5]helicene

Ir-catalyzed borylation of [5]helicene was studied for the first time. The obtained results indicate that borylation proceeded preferentially at the 2- and 3-positions. By using an appropriate catalytic system, 3-borylated [5]helicene can be formed as the major product in a high yield and regioselectivity (up to 89%, 8 : 1 ratio of isomers). The monoborylated [5]helicenes were further utilized in a Suzuki–Miyaura cross-coupling reaction to produce 2- or 3-arylated helicenes in very good isolated yields (80–94%).

Pyridine N -Oxides and Derivatives Thereof in Organocatalysis

Pyridine N-oxides are a class of mild Lewis bases that can activate certain kinds of Lewis acidic parts of molecules and hence increase reactivity of its nucleophilic part towards various reactions with electrophiles. This review aims to summarize the applications of various non-chiral and chiral pyridine N-oxides in catalysis of a variety of reactions. In addition, the applications of these reactions in syntheses of natural and bioactive compounds are mentioned as well.