Cu(I)-Catalyzed 1,2-Alkynyl-propargylation and -benzylation of Benzyne Derivatives.

We report here a three-component, Cu(I)-catalyzed hexadehydro-Diels-Alder (HDDA) benzyne 1,2-difunctionalization reaction. This protocol allowed the introduction of two different carbon-based substituents onto the in situ-generated benzyne. These substituents were terminal monoynes or diynes partnered with propargylic, benzylic, or allylic chlorides. An example of a sequential HDDA reaction is demonstrated using the product of a 1,3-diyne and a propargylic halide, itself a newly created HDDA precursor.

Electrocatalytic redox neutral [3 + 2] annulation of N-cyclopropylanilines and alkenes.

Although synthetic organic electrochemistry (EC) has advanced significantly, net redox neutral electrosynthesis is quite rare. Two approaches have been employed to achieve this type of electrosynthesis. One relies on turnover of the product by the reactant in a chain mechanism. The other involves both oxidation on the anode and reduction on the cathode in which the radical cation or the radical anion of the product has to migrate between two electrodes. Herein, a home-built electrochemistry/mass spectrometry (EC/MS) platform was used to generate an N-cyclopropylaniline radical cation electrochemically and to monitor its reactivity toward alkenes by mass spectrometry (MS), which led to the discovery of a new redox neutral reaction of intermolecular [3 + 2] annulation of N-cyclopropylanilines and alkenes to provide an aniline-substituted 5-membered carbocycle via direct electrolysis (yield up to 81%). A chain mechanism, involving the regeneration of the substrate radical cation and the formation of the neutral product, is shown to be responsible for promoting such a redox neutral annulation reaction, as supported by experimental evidence of EC/MS.

Difunctionalization of Cyclopropyl Amines with N-Iodosuccinimide (NIS) or in Situ Formed Cyanogen Iodide (ICN).

We report herein a 1,3-difunctionalization of cyclopropylamines that serve as a π nucleophile in a two-electron (2e) SN2-like ring opening pathway. N-Iodosuccinimide (NIS) or in situ generated cyanogen iodide (ICN) is employed as electrophilic iodinating reagents in conjunction with TMSCN or succinimide to furnish multiple pairs of functional groups disposed in a 1,3-manner. This 2e ring opening manifold overcomes the constraint of our previously reported 1e protocol as demonstrated by successful activation of monocyclic tertiary cyclopropylamines.

A Photocatalyzed Cascade Approach Toward the Tetracyclic Core of Akuammiline Alkaloids.

A cascade approach toward the tetracyclic core of akuammiline alkaloids which features high modularity and convergence is reported. Distinct substitution pattern can be readily introduced to the tetracyclic core by varying three building blocks with similar complexity. The critical event in the cascade is a regio- and stereoselective 1,2-shift enabled by a carbocation that sets up the core.

PhI(OAc)2-mediated synthesis of 6-(trifluoromethyl)phenanthridines by oxidative cyclization of 2-isocyanobiphenyls with CF3SiMe3 under metal-free conditions.

A mild and efficient method for the synthesis of 6-(trifluoromethyl)phenanthridines through oxidative cyclization of 2-isocyanobiphenyls with CF3SiMe3 under metal-free conditions was developed. The reaction allows the direct formation of C-CF3 bonds and rapid access to phenanthridine ring systems in one catalytic cycle.