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Topochemical photodimerization of (E)-3-benzylidene-4-chromanone derivatives from β-type structures directed by halogen groups
- Source :
-
Tetrahedron . Nov2011, Vol. 67 Issue 47, p9093-9098. 6p. - Publication Year :
- 2011
-
Abstract
- Abstract: Halogen substituent plays an important role in the crystalline packing of aromatic compounds. The [2+2] photocycloaddition of (E)-3-benzylidene-4-chromanones in the crystalline state was investigated, and halogen substitution has been adopted to organize molecules with proper arrangement for photodimerization. Not halogen bonds, but the electron-withdrawing property of halogen atoms can enhance the face-to-face π–π interactions. Therefore, F, Cl or Br substitution at the para position of phenyl gave rise to almost the same β-structures with face-to-face π-stacking. Only resulted β-structures can undergo photodimerization, which gave the syn-HH (syn-head-to-head) products with high regio-/stereoselectivity. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 00404020
- Volume :
- 67
- Issue :
- 47
- Database :
- Academic Search Index
- Journal :
- Tetrahedron
- Publication Type :
- Academic Journal
- Accession number :
- 66866856
- Full Text :
- https://doi.org/10.1016/j.tet.2011.09.087