Domino Reactions through Recursive Anionic Cascades: The Advantageous Use of Nitronates

Abstract

Recursive Anionic Cyclization (RAC) continues to proliferate as a mechanistically distinct domino strategy. Deployment of nitroalkanes as a source of recursive carbanions has created a niche operating space for generating molecular complexity and diversity. This new corollary i. e. recursive nitronate cyclization is the basis of a domino [5 C+1 C] cyclization strategy wherein nitroalkanes act as one‐carbon lynchpin, providing rapid access to topologically intriguing, densely functionalized carbo‐ and heterocycles embodying multiple chiral centers with regio‐, stereo‐ and enantioselectivity. Extension to aromatic domains, particularly via benzannulation reactions, has further consolidated the operating space. While leveraging the functional versatility of nitro group for post‐domino modifications, such endeavors have culminated in total synthesis of diverse natural products. An incisive analysis of recursive nitronate cyclizations and their emergent potentials is delineated in this review. It is hoped that this focused narrative will enthuse and draw new practitioners to the arena to advance the field.

Enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalysed by Cu(ii) complexes bearing binaphthyl–proline hybrid ligands

“…In our previous reports, we have shown that new chiral ligands with good performance could be obtained via the combination of binaphthyl 8 and proline 9 moieties. For example, chiral ligands 1 showed good performance in enantioselective addition of diethylzinc to different aldehydes.…”

Indeno-Annulation of o-Formyl-Ynones, o-Bis-Ynones, and p-Bis-o-Formyl-Ynones with Dimethyl Acetone-1,3-Dicarboxylate: One Flask Cascade Synthesis of Functionally Endowed 9-Fluorenols and Indeno[1,2-b]fluorenols

“…Intrinsic to such an approach is the possibility of execution in one flask operation through tandem/domino processes which in turn minimize the number of follow-on and work-up steps. The expected outcome from such tactics would be the expeditious delivery of complex, functionally embellished polycyclic scaffolds with reduction in the number of chemical and operational interventions …”

An Approach to Functionally Embellished o-Alkynylbenzoates or Furan-3(2H)-ones from Diynones and DMAD: Controlled Divergence and Product Selectivity

“…Among the choices available for multifunctional partners for engaging diynone 1 , table top dimethyl-1,3-acetone dicarboxylate (DMAD) with two active methylene sites appeared to offer attractive possibilities as it could trigger a base mediated tandem reaction cascade through either Michael–Michael or Michael–anti-Michael additions to diynones. The anticipated outcomes (not counting the possible reactivity of the two methylene derived anions undergoing Michael additions in recursive mode), providing access to fully functional eight- or seven-membered-ring products in a one-pot operation, appeared to be an alluring prospect as depicted in Scheme , and such possibilities have some precedence in the recently observed reactivity of diynones . The reaction between diynones and DMAD chartered deviant, albeit new and interesting courses as displayed in Scheme , leading either to multifunctional arenes 8 or furan-3­(2 H )-ones 9 depending on the reaction conditions.…”