E-viri
Recenzirano
-
Poisson, Carl; Lacoste, Jean-Éric; Rochon, Fernande D.; Breau, Livain
Tetrahedron: asymmetry, 11/2009, Letnik: 20, Številka: 21Journal Article
Various 2-substituted- N-benzyl-4,4,7-trimethyl- trans-octahydro-1,3-benzoxazines 2 were prepared from the condensation of (−)-8-benzylaminomenthol 1 derived from (+)-pulegone, with acrolein, crotonaldehyde, cinnamaldehyde, 2( E)- N, N-diisopropyl-4-oxobut-2-enamide, ethyl (2 E)-4-oxobut-2-enoate, and 2-furaldehyde in 71–96% yield. The 1,3-dipolar cycloaddition with aceto- and benzonitrile oxide gave the corresponding 2-isoxazoline cycloadducts. The origin of the stereoselectivity (4′ S, 5′ S-cycloadducts up to 64% de) arises from the cycloaddition of the dipole to the top of the Re,Re-alkene face of dipolarophile 2.
