Vinyl-aziridines and cyclopropanes in Pd-catalyzed (3+2)-cycloaddition reactions with cyclic N-sulfonyl imines

Synergistic Palladium-Phosphoric Acid Catalysis in (3 + 2) Cycloaddition Reactions between Vinylcyclopropanes and Imines

“…The reaction proceeded smoothly in all solvents testes, with diastereoselectivities comparable or lower than in toluene (compare entries 10-12 with entry 6). Halide salts are often used as additives in reactions involving zwitterionic allyl palladium intermediates [9,27]. By coordinating palladium, these additives increase the rate of π-σ-π isomerization of the allyl palladium complex [28], ultimately influencing the stereochemical outcome of the reactions (vide infra).…”

“…Vitale and co-workers reported closely related results [8], but extended the reaction to other VCPs, and to N-tosyl aldimines derived from aromatic and aliphatic aldehydes (Scheme 2, middle). Sulfamate-derived cyclic imines were also employed by de Figueiredo, Campagne and co-workers in palladium catalyzed cycloadditions with more elaborated 2-alkyl-2-alkylidene cyclopropane 1,1-dicarboxylates VCPs [9]. More recently, Chu, He, Liu and co-workers published the first examples of highly enantioselective (3 + 2) cycloadditions between VCPs and imines [10] (Scheme 2, bottom).…”

“…Implementation to a three-component version by forming the imine in situ is also possible, while the acid catalyst component (B) introduces a new option [17] for enantioinduction in VCPs reactions, beyond the common strategy based on chiral ligands at palladium. A similar approach has been briefly explored, but then abandoned in favor of chiral ligands, by de Figueredo, Campagne and co-workers during their studies on palladium catalyzed enantioselective 2-vinylaziridines cycloadditions [9]. On the other hand, a distinct synergistic catalysis combination was used in enantioselective cycloadditions between VCPs and enals [18][19][20][21][22], wherein chiral secondary amine and achiral palladium catalysis were successfully merged [23].…”

Pd-catalyzed [3 + 2] cycloaddition of cyclic ketimines and trimethylenemethanes toward N-fused pyrrolidines bearing a quaternary carbon

“… 9 For the preparation of sulfamate-fused pyrrolidines, the Pd-catalyzed [3 + 2] cycloaddition between vinylcyclopropanes and sulfamate-derived aldimines has been developed, which demonstrated high efficiency under mild reaction conditions ( Scheme 1a ). 10 An asymmetric strategy based on the organocatalytic Mannich/Aza-Michael cascade reaction using cis δ-formyl α,β-unsaturated ketones with sulfamate-derived aldimines has also been reported ( Scheme 1b ). 11 In stark contrast to the cycloadditions of sulfamate-derived aldimines, only recently have a few examples of catalytic cycloadditions of sulfamate-derived ketimines generating quaternary carbons in nitrogen-containing heterocycles been reported, and they involved a limited number of ketimines, such as cyclic N -sulfonyl trifluoromethylated ketimines 12 and styryl-substituted ketimines.…”

Electron-Deficient Alkynes as Dipolarophile in Pd-Catalyzed Enantioselective (3 + 2) Cycloaddition Reaction with Vinyl Cyclopropanes

“…Since the seminal works of Tsuji on the (3 + 2) cycloaddition of activated vinyl cyclopropanes with acrylates under the effect of palladium catalysis in 1985, significant advancements have been made in this field. Not only activated alkenes but also many other kinds of unsaturated compounds, including aldehydes, ketones, imines, heterocumulenes, as well as allenes, have been successfully used as dipolarophiles in the reaction. In addition, the asymmetric versions of the reaction have been developed rapidly, affording a variety of optically active five-membered heterocycles and cyclopentane derivatives. − ,,,,,, Aromatics have also been applied in an asymmetric dearomatization manner .…”