Polycyclic heteroaromatics via hydrazine-catalyzed ring-closing carbonyl–olefin metathesis

Abstract

The use of hydrazine-catalyzed ring-closing carbonyl-olefin metathesis (RCCOM) to synthesize polycyclic heteroaromatic (PHA) compounds is described. In particular, substrates bearing Lewis basic functionalities such as pyridine rings and amines, which...

Deaminative ring contraction for the synthesis of polycyclic heteroaromatics: a concise total synthesis of toddaquinoline

“…Given the simple starting materials, this strategy can be readily applied to prepare substituted polycyclic (hetero)aromatics with utility as the diversifiable cores of many bioactive polycyclic natural products, 3,28 ligands for catalysis, 25 and the organic components for the discovery of novel materials. 26,51…”

“…To highlight the efficiency and exibility of the developed strategy, both natural and isomeric variations are straightforward to access. The build-cyclizecontract strategy provides efficient access to C3-desoxytoddaquinoline 24m (85%), 28,44 C3-desoxy-toddaisoquinoline 24n (83%), 26 santiagonamine core 24o (28%), 7 and an isomeric santiagonamine core 24p (54%). This general efficiency prompted us to evaluate the build-cyclize-contract strategy to realize a concise total synthesis of toddaquinoline 3.…”

Hetero-ene Metathesis

“…While there are precedents of this process for several systems, , fragmentation of other heterocycles is less certain. Even for pyrazolidines, this fragmentation requires high reaction temperatures ranging from 75 to 160 °C, depending on substrate identity, ,− , which presents a hurdle for the generalization of this methodologyparticularly in the case of temperature-sensitive substrates . An additional challenge is the slow hydrolysis of the product azomethine imine, which is required to regenerate the catalyst.…”

Cation–anion confined hydrogen-bonding catalysis strategy for ring-closing C–O/O–H metathesis of alkoxy alcohols under metal-free conditions

“…Metathesis reactions are widely applied to synthesize complex molecules, pharmaceuticals, and natural products. [1][2][3][4][5][6][7] Particularly, ring-closing metathesis (RCM) reactions of multiple bonds, such as olefin-olefin metathesis 2,[8][9][10][11] and carbonyl-olefin metathesis 5,[12][13][14][15][16] have become powerful techniques for the preparation of various unsaturated rings in organic synthesis (Scheme 1a and b). In contrast, the RCM reactions of the C-X bond especially involving the C-O bond are rarely reported and still challenging owing to the low reactivity of single bonds.…”