Pd/LA-catalyzed decarboxylation enabled exclusive [5 + 2] annulation toward N-aryl azepanes and DFT insights

Abstract

A practical and straightforward methodology toward the synthesis of non-fused N-aryl azepane derivatives with diversity is described. These Pd/LA-catalyzed reactions proceed smoothly under extremely mild conditions with ample reaction scope...

Pd-Catalyzed asymmetric decarboxylation for the construction of spiro[4.5]deca-6,9-dien-8-ones featuring vicinal quaternary carbons

“…The transition metal-catalyzed decarboxylation of cyclic carbonates has proven to be a feasible and versatile methodology for creating interesting and valuable compounds in recent years. 8 Such an approach gains extensive research interest due to its redox neutrality, only CO 2 -byproduct generation and user-friendly experimental workup. Specifically, our group recently reported the decarboxylative annulation of rationally designed vinyl methylene carbonate A and activated alkenes toward the racemic formation of carbocycles under palladium catalysis (Scheme 1b), in which the carbonate offers a well-stabilized C–C dipole intermediate with enolate and Pd-allyl fragments upon decarboxylative catalysis.…”

Zwitterionic Metal Enolates or Equivalents: Generation and Capture

“…In the presence of Ag-OTf as a Lewis acid catalyst, intermediate T1 reacts with Narylmethanimines, generated in situ from 1,3,5-triazines, to give seven-membered N-arylazepanones (Scheme 3, path d). 16 The formal synthesis of a pharmaceutically relevant Nphenylproheptazine derivative was accomplished by using this protocol. The excellent regioselectivity was further explained by means of DFT calculations.…”

“…13 Our group recently designed a batch of different functionalized methene carbonates A, B, and C, the decarboxylation of which under transition-metal catalyst generates the corresponding zwitterionic metal enolate (ZME) intermediates T1-3 or their equivalents (Scheme 2). [14][15][16][17][18][19][20] We have proved that these ZME intermediates can be captured by various reaction partners to afford various, optionally enantioenriched, functionalized ketones or their derivatives, some of which are otherwise synthetically quite challenging. More specifically, with regard to the ZME intermediates, the enolate portion not only works as a precursor of a carbonyl functionality, but also acts as hydrogen-bonding acceptor that might assist in the introduction of high enantioselec-tivity or regioselectivity; the metal-containing cation fragment permits a wide choice of versatile catalytic systems.…”

Recent Advances in Decarboxylative Conversions of Cyclic Carbonates and Beyond

“…Scheme 17 Pd-catalyzed decarboxylative [5+2] annulations of VMCCs with triazines; (i), (vi) and (vii) refer to specific steps in the formal synthesis 25 The zwitterionic enolate intermediate could be captured by amine nucleophiles as well. Our group recently reported a Pd-catalyzed decarboxylation process that enabled the [4+1] annulation of VMCCs with amines as reaction partners toward the generation of pyrroles (Scheme 18).…”

“…Our group recently reported the utilization of this concept for the synthesis of functionalized non-fused seven-membered azepanes by using triazines as reaction partners (Scheme 17). 25 This catalytic system tolerates various functional groups present either in the VMCCs or the triazine partners. The AgOTf Lewis acid catalyst enables the in situ formation of an imine electrophile from the triazine precursor.…”