Artículos de revistas
Stereoselective synthesis of novel diels-alder adducts of p-substituted Methyl Thiocinnamates and Cyclopentadiene
Fecha
2012Registro en:
SYNTHETIC COMMUNICATIONS, PHILADELPHIA, v. 42, n. 3, pp. 394-401, DEC 15, 2012
0039-7911
10.1080/00397911.2010.524962
Autor
Camilo, Fernanda F.
Gruber, Jonas
Institución
Resumen
This article describes the Diels-Alder reaction between methyl thiocinnamates, substituted at the para position by electron-donating and electron-withdrawing groups, with cyclopentadiene in the presence of catechol boron bromide (CBB) as a Lewis acid catalyst. The adduct configuration was confirmed by H-1 NMR coupling constants and single-crystal x-ray diffraction. Total endo stereoselectivity was observed in all reactions and was attributed to the effective secondary interaction between the boron atom and the incipient double bond in the norbonene resulting from the planar geometry of the catalyst. C-13 NMR chemical shifts of the coordinated dienophile carbonyl carbons with CBB compared to those of the non coordinated thiocinammates suggest a strong complexation with the catalyst.