Addition-cyclization Cascade Research Articles

ChemInform Abstract: Vinyl Selenones: Annulation Agents for the Synthesis of Six‐Membered Benzo‐1,4‐heterocyclic Compounds.

Abstract A novel and general approach to six-membered bicyclic benzo fused 1,4-heterocycles is described. The addition–cyclization cascade of benzo 1,2-diols, 1,2-thiols and 2-(benzylamino)phenols with stable and easily available vinyl selenones affords differently substituted 2,3-dihydro-1,4-benzodioxines, benzodithiines and 3,4-dihydro-2H-1,4-benzoxazines in good yields. The same procedure has been extended to the synthesis of 1,2,3,4-tetrahydroquinoxalines. All of these heterocycles are present in a variety of biologically active compounds.

Efficient Synthesis of N-(9-Xanthyl)-4-Toluenesulfonamides Enabled by an Addition-Cyclization Cascade of Arynes

An efficient synthesis of <i>N</i>-(9-xanthyl)-4-toluenesulfonamides is described in which salicyl <i>N</i>-tosylimines react with silyl­aryl triflates in the presence of CsF. This mild process involves an addition–cyclization cascade in which arynes are generated and trapped in situ.

Vinyl selenones: annulation agents for the synthesis of six-membered benzo-1,4-heterocyclic compounds

A novel and general approach to six-membered bicyclic benzo fused 1,4-heterocycles is described. The addition–cyclization cascade of benzo 1,2-diols, 1,2-thiols and 2-(benzylamino)phenols with stable and easily available vinyl selenones affords differently substituted 2,3-dihydro-1,4-benzodioxines, benzodithiines and 3,4-dihydro-2H-1,4-benzoxazines in good yields. The same procedure has been extended to the synthesis of 1,2,3,4-tetrahydroquinoxalines. All of these heterocycles are present in a variety of biologically active compounds.

ChemInform Abstract: Asymmetric Organocatalytic Michael Addition—Cyclization Cascade Reaction of Nitroalkanes with o‐Hydroxycinnamaldehydes.

AbstractThe chroman‐2‐ols are obtained in high yields and enantioselectivities.

ChemInform Abstract: Highly Enantioselective Conjugate Addition—Cyclization Cascade Reaction of Malonates with o‐Hydroxycinnamaldehydes: Asymmetric Synthesis of 4‐Substituted Chromanols.

AbstractThe title reaction provides a mild and facile approach to enantioenriched 4‐substituted chromanols.

Asymmetric Organocatalytic Michael Addition–Cyclization Cascade Reaction of Nitroalkanes with o‐Hydroxycinnamaldehydes

AbstractA catalytic enantioselective Michael addition–cyclization reaction of nitroalkanes with o‐hydroxycinnamaldehydes has been established by using a diphenylprolinol TMS ether as an organocatalyst. The reaction afforded the corresponding 4‐substituted chroman‐2‐ols in excellent yields with high levels of enantioselectivities (95 to &gt;99 % ee).

Highly Enantioselective Conjugate Addition–Cyclization Cascade Reaction of Malonates with o‐Hydroxycinnamaldehydes: Asymmetric Synthesis of 4‐Substituted Chromanols

AbstractThe asymmetric organocatalytic conjugate addition–cyclization reaction of malonates with o‐hydroxycinnamaldehydes, which affords 4‐substituted chroman‐2‐ols, has been established using a diphenylprolinol trimethylsilyl (TMS) ether as organocatalyst. The desired products were obtained with good to excellent yields and high enantioselectivities (up to &gt;99% ee). Synthetically useful chroman derivatives were formed after subsequent reactions.

Efficient and general synthesis of oxazino[4,3-a]indoles by cascade addition-cyclization reactions of (1H-indol-2-yl)methanols and vinyl sulfonium salts

An efficient and general approach to oxazino[4,3-a]indole architectures is described. The addition-cyclization cascade of (1H-indol-2-yl)methanols with vinyl sulfonium salts affords oxazino[4,3-a]indole derivatives in high yields.