Pd-Catalyzed asymmetric [5 + 2] cycloaddition of vinylethylene carbonates and cyclic imines: access to N-fused 1,3-oxazepines

Abstract

A facile route to access enantioenriched N-fused 1,3-oxazepines via Pd-catalyzed asymmetric [5 + 2] cycloaddition of vinylethylene carbonates and cyclic imines has been developed.

Advances in Palladium‐Catalyzed Decarboxylative Cycloadditions of Cyclic Carbonates, Carbamates and Lactones

“…Employing chiral phosphoramidite L3 as ligand, regiospecific [3+2] cycloadducts 1,3‐oxazolidines 15 were obtained in high yields (up to 96 %) and stereoselectivities (up to 25 : 1 dr, >99 % ee ) (eq 1) [12a] . Whereas using chiral phosphine ( S )‐SegPhos as ligand, the seven‐membered 1,3‐oxazepines 16 were mainly obtained in good yields (up to 89 %) and enantioselectivities (up to 80 % ee ) via a [5+2] cycloaddition reaction (eq 2) [12b] . Soon after, asymmetric palladium‐catalyzed decarboxylative [3+2] cycloadditions of VECs 8 with sulfamate‐derived cyclic imines 14 were also realized by Zheng and Guo with spiroketal‐based diphosphine (−)‐SKP as a chiral ligand [12c] …”

High-order dipolar annulations with metal-containing reactive dipoles

“…Oxazol-5-(4 H )-ones 120 , cyclic aldimines 122 and electron-deficient olefins 124 have also been utilized by many other researchers as suitable reaction partners with VECs, and they have delivered many kinds of functionalized 7-membered rings (Scheme 27). 71–74 In addition to VECs 96 , vinyloxiranes 119 can be used to generate the same nucleophilic 1,5-dipole.…”

Visible-light-induced cyclization of cyclic N-sulfonyl ketimines to N-sulfonamide fused imidazolidines

“…1 Among them, compounds containing a cyclic N -sulfonamide moiety have versatile applications in biological molecules with therapeutic activities, such as HIV protease inhibitors, 2 potential modulators of neurotransmitters, 3 inhibitors of carbonic anhydrase, 4 and so on. 2 Over the past decades, a great deal of effort, including nucleophilic addition, 5 annulation reactions, 6 ring expansion, 7 and C–H functionalization 8 of cyclic sulfonyl ketimines, has been devoted to increasing the complexity of cyclic N -sulfonamides. However, a transition metal is generally required to achieve meaningful transformations.…”