Nitrone Cycloadditions of 1,2-Cyclohexadiene

Theoretical study of 1, 3-dipolar cycloadditions of nitrone and fulminic acid with substituted ethylenes

[2n2π + 2n2π] cycloadditions: an alternative to forbidden [4π + 4π] processes. The case of nitrone dimerization.

A theoretical study based on (U)M06-2X/cc-pVTZ calculations has been used to investigate the [3 + 3] thermal dimerization of nitrones to 1,4,2,5-dioxadiazinanes in both the gas phase and in dichloromethane solution. Calculations suggest that dimerization of nitrones takes place through a concerted mechanism involving a formal disallowed [4π + 4π] cycloaddition with a free energy barrier of 30.8...

Fused tetracycles with a benzene or cyclohexadiene core: [2 + 2 + 2] cycloadditions on macrocyclic systemsw

The transition-metal-catalyzed [2 + 2 + 2] cycloaddition of alkynes is an interesting method for synthesizing polysubstituted benzene derivatives. When running this reaction intramolecularly, three fused rings are formed in one synthetic operation. Furthermore, when it is performed in a closed system, i.e. a macrocycle, the reaction leads to fused tetracycles, which is a highly attractive synth...

Fused tetracycles with a benzene or cyclohexadiene core: [2 + 2 + 2] cycloadditions on macrocyclic systems.

A series of fused tetracycles with a benzene or cyclohexadiene core (2a-h) is satisfactorily prepared by intramolecular [2 + 2 + 2] cycloadditions of triynic and enediynic macrocycles (1a-h) under RhCl(PPh3)3 catalysis; the enantioselective cycloaddition of macrocycles 1b and 1e and gives chiral tetracycles with moderate enantiomeric excess.

Enantioselective nitrone cycloadditions of alpha,beta-unsaturated 2-acyl imidazoles catalyzed by bis(oxazolinyl)pyridine-cerium(IV) triflate complexes.

[Structure: see text] Enantioselective nitrone cycloadditions with beta-substituted alpha,beta-unsaturated 2-acyl imidazoles catalyzed by bis(oxazolinyl)pyridine-cerium(IV) triflate complexes 1 have been reported. The isoxazolidine products were efficiently transformed into densely functionalized beta'-hydroxy-beta-amino acid derivatives.