Ag(i)/(S,S)-ip-FOXAP catalyzed diastereo- and enantioselective 1,3-dipolar cycloaddition of azomethine ylides with benzosultam-3-ylidenes

Abstract

The AgOAc/ip-FOXAP complex catalyzed the highly diastereo- and enantioselective 1,3-dipolar cycloaddition of azomethine ylides with benzosultam-3-ylidenes to give single isomer of the exo-cycloadducts in good yields. For azomethine ylides, the...

Catalytic Enantioselective [3+2] Cycloaddition of N‐Metalated Azomethine Ylides

“…Using iPr-FcPHOX ligand L4 a, Teng's group developed an exo-selective asymmetric 1,3-dipolar cycloaddition of imino esters 1 with benzosultam-3-ylidines 66 by Ag-catalysis. [44] A variety of benzosultam-3-ylidenes and substituted imino esters were well tolerated to give the products 67 with excellent levels of exo-selectivity in 64-95 % yields and 90-99 % ee (Scheme 36). The reaction yields were only marginally affected by the imino ester electronic properties, and asymmetric induction was lowered to 63 % ee for the formation of the sterically crowed omethyl-substituted aryl-containing benzosultam-3-ylidine 67 h. The related cycloadduct 67 i were also obtained in good yields and enantioselectivities by employing an imino amide as substrate.…”

“…Using i Pr‐FcPHOX ligand L4 a , Teng's group developed an exo ‐selective asymmetric 1,3‐dipolar cycloaddition of imino esters 1 with benzosultam‐3‐ylidines 66 by Ag‐catalysis [44] . A variety of benzosultam‐3‐ylidenes and substituted imino esters were well tolerated to give the products 67 with excellent levels of exo ‐selectivity in 64–95 % yields and 90–99 % ee (Scheme 36).…”

Chiral Cyclopropenimine‐catalyzed Asymmetric Michael Addition of Bulky Glycine Imine to α,β‐Unsaturated Isoxazoles

“…The compounds containing isoxazole core exhibit unique bioactivities with anti‐cancer, [13] antimicrobial [14] and anti‐inflammatory effects [15] . The benzophenone‐protected glycine derivatives (glycine imines) were used as readily available starting materials in many transformations including Michael addition, [16–18] alkylation [19–21] and [3+2] cycloaddition [22–25] . Unfortunately, glycine imines have α‐H with high p K a values, they are challenging substrates for base‐catalyzed Michael additions.…”

“…[15] The benzophenone-protected glycine derivatives (glycine imines) were used as readily available starting materials in many transformations including Michael addition, [16][17][18] alkylation [19][20][21] and [3 + 2] cycloaddition. [22][23][24][25] Unfortunately, glycine imines have α-H with high pK a values, they are challenging substrates for base-catalyzed Michael additions. The combination of Cu (I) or silver salts with chiral ligands is usually used for asymmetric Michael additions of glycine imines and nitroalkenes.…”