retro-Cheletropic ene reactions with 2-carbena-1,3-dioxolane as chelefuge

Cobalt-catalyzed C(sp2)-H bond imination of phenylalanine derivatives

Herein we report the cobalt-catalyzed, picolinamide-directed C-H bond imination protocol of phenylalanine derivatives using isocyanides and a Co(dpm)₂ catalyst. A wide range of functional groups were tolerated under the reaction conditions, yielding imines in high yields. The obtained imine products can easily be transformed to 1-aminoisoquinoline derivatives under reductive conditions, providing an attractive alternative to already existing methodologies. The control experiments indicated that C-H activation might occur via an electrophilic pathway.

Copper-catalyzed cyclization of 2-cyanobenzaldehydes and 2-isocyanoacetates: an efficient strategy for the synthesis of substituted 1-aminoisoquinolines

An efficient strategy for the synthesis of substituted 1-aminoisoquinoline has been developed.

Tandem processes promoted by a hydrogen shift in 6-arylfulvenes bearing acetalic units at ortho position: a combined experimental and computational study

6-Phenylfulvenes bearing (1,3-dioxolan or dioxan)-2-yl substituents at ortho position convert into mixtures of 4- and 9-(hydroxy)alkoxy-substituted benz[f]indenes as result of cascade processes initiated by a thermally activated hydrogen shift. Structurally related fulvenes with non-cyclic acetalic units afforded mixtures of 4- and 9-alkoxybenz[f]indenes under similar thermal conditions. Mechanistic paths promoted by an initial [1,4]-, [1,5]-, [1,7]- or [1,9]-H shift are conceivable for explaining these conversions. Deuterium labelling experiments exclude the [1,4]-hydride shift as the first step. A computational study scrutinized the reaction channels of these tandem conversions starting by [1,5]-, [1,7]- and [1,9]-H shifts, revealing that this first step is the rate-determining one and that the [1,9]-H shift is the one with the lowest energy barrier.

Acid-promoted cycloisomerizations of phenylallenes bearing acetalic functions at the ortho position: a stereocontrolled entry to indeno-fused dioxepanes, dioxocanes and thioanalogues

Two different approaches convert ortho acetal-substituted phenylallenes into several classes of indeno-fused heterocycles.

N-Phenyl-1-methyl-6-methylenecyclohexa-2,4-dienylmethanimine retro cheletropic-ene reaction, a theoretical kinetic study

Structural and kinetic aspects of the retro-cheletropic ene reactions of N-phenyl-1-methyl-6-methylenecyclohexa-2,4-dienylmethanimine (R) and its deuterated derivative were investigated using a variety of computational methods. Theoretical calculations were carried out with DFT methods at the B3LYP and M06 levels of theory, using the 6-311++G(d,p) basis set. Vibrational frequency analysis confirmed the stationary states including the transition state (TSs) structures. The mechanistic studies on the retro-cheletropic ene processes rejected the stepwise mechanism and confirmed a five-membered cyclic TS for the reaction. The conversion of the reactant to the products proceeds through an asynchronous concerted mechanism. Theoretical calculations indicate that the reaction displays a primary kinetic isotope effect of 8.75 at 417 K. Calculated activation parameters, especially M06 results, are in good agreement with the experimental data. The natures of bond making and breaking during the reactions have been investigated using the concepts of donor–acceptor, electron charge density and Laplacian in NBO and AIM methods, respectively.