Revisiting the 1,3-azadiene-succinic anhydride annulation reaction for the stereocontrolled synthesis of allylic 2-oxopyrrolidines bearing up to four contiguous stereocenters

Polysubstituted 2-oxopyrrolidines bearing at least two contiguous stereocenters constitute the core of several pharmaceuticals, including clausenamide (antidementia). Here, we describe a flexible annulation strategy, which unites succinic anhydride and 1,3-azadienes to produce allylic 2-oxopyrrolidines bearing contiguous stereocenters. The approach is chemoselective, efficient, modular, scalable, and diastereoselective. The scalable nature of the reactions offers the opportunity for post-diversification, leading to incorporation of motifs with either known pharmaceutical value or that permit subsequent conversion to medicinally relevant entities.

Leveraging the 1,3-azadiene-anhydride reaction for the synthesis of functionalized piperidines bearing up to five contiguous stereocenters

A modular and scalable strategy, which remodels 3-methylglutaric anhydride to 2-oxopiperidines bearing at least three contiguous stereocenters is described. The approach relies on the chemoselective and stereocontrolled annulation of 1,3-azadienes with the anhydride component. The resulting acid-tethered allylic 2-oxopiperidines are then engaged in several selective fragment growth processes, including catalytic denitrative alkenylation, halolactonization, and Vilsmeier-Haack functionalization.

Skeletal remodelling of α-substituted cyclic eneformamides to α-ketonyl cyclic amines

A modular dehomologation strategy, which skeletally remodels cyclic α-substituted eneformamides to one-carbon shorter α-ketonyl saturated cyclic amines is described.

Modular synthesis and transition metal-free alkynylation/alkenylation of Castagnoli–Cushman-derived N,O- and N,S-heterocyclic vinyl chlorides

A modular and functional group-tolerant protocol for the transition metal-free coupling of novel N,O- and N,S-heterocyclic vinyl chlorides with terminal acetylenes and styrenes has been developed, leading to the epimerization-free synthesis of fully carbofunctionalized dihydro-1,4-oxazines/thiazines. Bicyclic morpholines have also been prepared through the interrogation of newly synthesized cross-conjugated dienes in Diels–Alder reactions. The use of environmentally benign reaction media endows the current strategy with a practical advantage.

A functional group-tolerant and transition metal-free coupling of novel N,O- and N,S-heterocyclic vinyl chlorides, which affords fully carbosubstituted dihydro-1,4-oxazines/thiazines as well as bicyclic morpholines, is described.

One-shot access to isoquinolone and (hetero)izidinone architectures using cyclic α-chloro eneformamides and cyclic anhydrides

A site-selective annulation reaction between cyclic α-chloro eneformamides and cyclic anhydrides which provides direct and modular access to pharmaceutically pertinent izidinones and isoquinolones, is presented.

Copper-catalyzed regioselective dehydrogenative alkoxylation of morpholinonyl alkenols: application to the synthesis of spirotricyclic dihydropyrans and of trans-fused bicyclic morpholines

A base-free, regioselective, and atom-economical approach to morpholine-fused dihydropyrans, by Cu-catalyzed intramolecular dehydrogenative alkoxylation of allylic morpholinols, is described.

Expedient and modular access to 2-azabicyclic architectures by iron-catalyzed dehydrative coupling of alcohol-bearing allylic lactams

A high-yielding, cost-effective, modular and environmentally benign approach to [5,5]- or [6,5]-2-azabicyclic architectures bearing vicinal stereocenters, by Fe-catalyzed dehydrative coupling of readily affordable alcohol-bearing allylic lactams is presented.

Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides

A modular substrate-controlled hexannulation of 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.

Regiocontrolled synthesis of (hetero)aryl and alkenyl dehydropyrrolidines, dehydropiperidines and azepenes by Ru-catalyzed, heteroatom-directed α-C–H activation/cross-coupling of cyclic enamides with boronic acids

The synthesis of α-aryl and alkenyl pyrrolidine-, piperidine-, and azepane derivatives by ruthenium-catalyzed, carbonyl-assisted, site-selective sp² C–H activation of cyclic enamides and concomitant cross-coupling with boronic acids is described.

One-shot access to α,β-difunctionalized azepenes and dehydropiperidines by reductive cross-coupling of α-selenonyl-β-selenyl enamides with organic bromides

The synthesis of α- and α,β-functionalized azepenes and dehydropiperidines from readily prepared α-selenonyl eneformamides or enecarbamates has been achieved through Fe-catalyzed α-substitutive deselenonation, β-regioselective lithiation/trapping, and Co-catalyzed reductive cross-coupling protocols.

Trapping of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles: Controlling the formation of α-amino quaternary and vicinal stereocenters

The interception of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles has led to the diastereoselective synthesis of vicinally functionalized piperidines bearing α-amino quaternary stereocenters.

Effective 1,5-stereocontrol in Pd(0)/InI promoted reactions of chiral N-Ts-4-vinylazetidin-2-ones with aldehydes. An efficient entry into nonracemic semi-protected (3Z)-2,6-anti-enediols

ε-Amido-allylindiums generated from N-Ts-4-vinylazetidin-2-ones react with aldehydes with effective remote 1,5-stereocontrol to afford (3Z)-2,6-anti-enediols in good yield and with excellent diastereoselectivity.

Direct access to functionalized benzotropones, azepanes, and piperidines by reductive cross-coupling of α-bromo enones with α-bromo enamides

High-yielding syntheses of functionalized azepenes and piperidines, bearing an α-benzotropone derivative, have been achieved through cobalt-catalysed reductive cross-coupling of α-bromo enamides with α-bromo enones.