Synthesis of enantiopure 3-azabicyclo[3.2.0]heptanes by diastereoselective intramolecular [2+2] photocycloaddition reactions on chiral perhydro-1,3-benzoxazines.
[2+2] photocycloadditions involving chiral 3-acryloyl-2-vinylperhydro-1,3-benzoxazines derived from (-)-8-aminomenthol are highly diastereoselective reactions. The facial selectivity depends on the type of substitution at the vinyl double bond, and always leads to cis-fused bicyclic derivatives. The de is good for compounds with one substituent at the outer carbon of the double bond at C-2, but only one diastereomer is formed in cyclizations of compounds with two substituents at that position. The elimination of the menthol appendage gives enantiopure 3-azabicyclo[3.2.0]heptanes.
Pedrosa
Rafael
R
Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, Dr. Mergelina s/n, 47011-Valladolid, Spain. pedrosa@qo.uva.es
Andrés
Celia
C
Nieto
Javier
J
del Pozo
Soledad
S