Organocatalytic Enantioselective Intramolecular (Hetero)Michael Additions in Desymmetrization Processes

Organocatalytic Enantioselective Friedel‐Crafts Alkylation Reactions of Pyrroles

Two Decades of Progress in the Asymmetric Intramolecular aza-Michael Reaction.

The asymmetric intramolecular aza-Michael reaction (IMAMR) is a very convenient strategy for the generation of heterocycles bearing nitrogen-substituted stereocenters. Due to the ubiquitous presence of these skeletons in natural products, the IMAMR has found widespread applications in the total synthesis of alkaloids and biologically relevant compounds. The development of asymmetric versions of the IMAMR are quite recent, most of them reported in this century. The fundamental advances in this field involve the use of organocatalysts. Chiral imidazolidinones, diaryl prolinol derivatives, Cinchone-derived primary amines and quaternary ammonium salts, and BINOL-derived phosphoric acids account…

Intramolecular Cycloaddition Azomethine Ylides and α-(Trifluoromethyl)styrenes as Dipolarophiles

The synthesis of polycyclic fluorinated tertiary amines has been accomplished by means of an intramolecular azomethine ylide cycloaddition with fluorinated dipolarophiles. Thus, tri- and tetracyclic fused pyrrolidines bearing a quaternary trifluoromethyl group were obtained in moderated yields in a stereoselective manner. This is one of the few examples reported in the literature of intramolecular 1,3-dipolar cycloaddition of azomethine ylides with fluorinated dipolarophiles. Initial attempts of the asymmetric version of the process have been performed, but low levels of diastereoselectivity were achieved.

Organocatalytic enantioselective synthesis of 2,5,5-trisubstituted piperidines bearing a quaternary stereocenter. Vinyl sulfonamide as a new amine protecting group

An organocatalytic desymmetrizing intramolecular aza-Michael reaction with vinyl sulfonamides as nucleophilic nitrogen source has been devised for the synthesis of a new family of 2,5,5-trisubstituted piperidines bearing a quaternary sterocenter. The process takes place with excellent levels of enantioselectivity and moderate to good diastereoselectivity. The vinyl sulfonamide moiety can be removed by means of an ozonolysis reaction.

Intramolecular Cycloaddition Azomethine Ylides and α-(Trifluoromethyl)styrenes as Dipolarophiles

Unexpected metal-free synthesis of trifluoromethyl arenes via tandem coupling of dicyanoalkenes and conjugated fluorinated sulfinyl imines

A novel strategy for the synthesis of policyclic trifluoromethyl arenes has been devised. It involves a DBU-promoted tandem cycloaromatization reaction of dicyanoalkenes and fluorinated conjugated sulfinyl imines. This unprecedented transformation is a metal-free and air-tolerant process that takes place from readily available starting materials under mild reaction conditions.

CCDC 1989940: Experimental Crystal Structure Determination

Related Article: Alvaro Sanz-Vidal, Daniel Gaviña, Lia Sotorríos, Enrique Gómez-Bengoa, Fernando López Ortiz, María Sánchez-Roselló, Carlos del Pozo|2021|Chem.Commun.|57|8023|doi:10.1039/D1CC03161A

CCDC 1891128: Experimental Crystal Structure Determination

Related Article: Marcos Escolano, Marta Guerola, Javier Torres, Daniel Gaviña, Gloria Alzuet-Piña, María Sánchez-Rosello, Carlos del Pozo|2020|Chem.Commun.|56|1425|doi:10.1039/C9CC09113K

CCDC 1989936: Experimental Crystal Structure Determination

Related Article: Alvaro Sanz-Vidal, Daniel Gaviña, Lia Sotorríos, Enrique Gómez-Bengoa, Fernando López Ortiz, María Sánchez-Roselló, Carlos del Pozo|2021|Chem.Commun.|57|8023|doi:10.1039/D1CC03161A