Copper-Catalyzed Photoinduced Radical Domino Cyclization of Ynamides and Cyanamides: A Unified Entry to Rosettacin, Luotonin A, and Deoxyvasicinone

Abstract

A general and efficient procedure for the copper-catalyzed photoinduced radical domino cyclization of ynamides and cyanamides providing an efficient access to complex tri-, tetra- and pentacyclic nitrogen heterocycles is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF6 and an amine, a range of unactivated aryl and alkyl iodides were shown to be smoothly transformed to the corresponding radical species, initiating the radical domino cyclization. This procedure provides a unified entry to rosettacin, luotonin A, and deoxyvasicinone that could be efficiently prepared in a limited number of steps.

Rich or poor: the impact of electron donation and withdrawal on the photophysical and photocatalytic properties of copper(i) complexes

“…In this respect, the photocatalytic reductive dehalogenation of aryl halides represents a relevant benchmark reaction, which has been Catalysis Science & Technology Paper investigated in many past contributions. [93][94][95] Briefly, the reaction involves the cleavage of the carbon-halogen bond by reducing aryl halides Ar-X into the radical Ar˙and the halide X − , followed by protonation of Ar˙leading to Ar-H (see Scheme 1). In the case of copper(I) complexes, such strong reductive power is achieved when the excited state of the latter is reductively quenched by a sacrificial donor, affording the reduced copper(I) complex in its ground state.…”

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

“…Later in 2018, Evano and co-workers used their methodology to reduce aryl iodide for the synthesis of the alkaloids rosettacin, luotonin A, and deoxyvasicinone (Scheme 22) [37]. The developed strategy relied on the addition of an aryl radical on ynamides or cyanamides, followed by a final cyclization.…”

Photoredox- and piezo-catalysed access to complex trifluoromethylated polycyclic structures from ynamides

“…9 Initially run using stoichiometric amounts of the now undesirable Bu 3 SnH/AIBN mediating system (Scheme 1A) to perform the halogen atom abstraction, Evano judiciously upgraded this chemistry by reporting a copper photocatalyzed version of strategy I that relies on the reductive cleavage of a carbon–iodine bond to initiate the cyclization. 10…”