Synthesis of β- and γ-carbolines via ruthenium and rhodium catalysed [2+2+2] cycloadditions of yne-ynamides with methylcyanoformate

A flexible approach towards substituted β- and γ-carbolines based on transition metal catalysed [2+2+2] cycloaddition reactions between functionalised yne-ynamides and methylcyanoformate is described. The versatility of this new reaction sequence is demonstrated by its application in the total synthesis of the marine natural product eudistomin U.

Synthesis and molecular properties of donor–π-spacer–acceptor ynamides with up to four conjugated alkyne units

A set of push-pull ynamides with up to four conjugated triple bonds has been synthesized and the molecular properties of these new carbon rods have been characterised showing effective intramolecular charge transfers and high values for the change of the electrical dipole moment after transition from the ground to the Franck-Condon excited state.

First total synthesis of antiostatin A1, a potent carbazole-based naturally occurring antioxidant.

The first total synthesis of the potent antioxidant antiostatin A1 is reported, where its key features rely on a chemo- and regioselective rhodium-catalysed crossed alkyne cyclotrimerisation reaction applying functionalised ynamides and a palladium-catalysed arylamidation reaction.

Palladium-Catalyzed N-Arylation Reactions with Aziridine and Azetidine

Studies on the viability of palladium-catalyzed cross-coupling reactions of aryl- or hetaryl bromides with the parent aziridine or azetidine showed that a wide range of N-arylaziridines and N-arylazetidines are accessible by this method. Ring cleavage of the N-arylaziridines or -azetidines thus produced does not occur under the applied reaction conditions. The synthetic utility of the method is illustrated by examples of double N-arylations with either aziridine or azetidine.

New reactions and step economy: the total synthesis of (±)-salsolene oxide based on the type II transition metal-catalyzed intramolecular [4+4] cycloaddition

Studies on the viability of the type II nickel-catalyzed intramolecular [4+4] cycloaddition of bis-dienes show that it is influenced by both diene substitution and geometry. Both E- and Z-isomers of 19 and 20 react, albeit at markedly different rates, to afford cycloadducts, whereas only the Z-isomer of 9 (and not the E-isomer) reacts to give 8 and 25. Chemoselective elaboration of 8 to (±)-salsolene oxide (7) was used to confirm the cycloadduct structure while establishing a step economical route to the natural product.

Catalytic Enantioselective α-Oxysulfonylation of Ketones Mediated by Iodoarenes

The alpha-oxysulfonylation of ketones catalysed by enantioenriched iodoarenes using mCPBA as stoichiometric oxidant is reported to give useful synthetic intermediates in good yield and modest enantioselectivity. We believe this to be the first report of an enantioselective organocatalytic reaction involving hypervalent iodine reagents which should open up a new field for enantioselective organocatalysis of oxidation reactions.

ChemInform Abstract: Aliphatic and Alicyclic Aldehydes: Synthesis by Diels-Alder Reactions with Enals or Their Acetals

[2+2+2] Cycloadditions of Alkynylynamides - A Total Synthesis of Perlolyrine and the First Total Synthesis of “Isoperlolyrine”

The total syntheses of the carboline alkaloids perlolyrine and "isoperlolyrine" are reported. Key-steps of the syntheses are Negishi coupling reactions on alkynylynamides and their metal-catalyzed [2+2+2] cycloadditions with nitriles to form the β- and γ-carboline cores. The choice of the catalyst strongly affects the β/γ ratio. Spectroscopic features of the γ-isomer are distinctly different from those of the naturally occurring isoperlolyrine.