Synthesis of new substituted dihydroheptalene derivatives: SiO2- and base-catalyzed rearrangement of dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate


SARACOGLU N., MENZEK A., Kinal A. , BALCI M.

CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE, cilt.79, ss.35-41, 2001 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 79 Konu: 1
  • Basım Tarihi: 2001
  • Doi Numarası: 10.1139/cjc-79-1-35
  • Dergi Adı: CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE
  • Sayfa Sayıları: ss.35-41

Özet

Dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate (trans-3) isomerizes to dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate (cis-3) upon treatment with SiO2. On the other hand, base-catalyzed reaction of trans-3 undergoes a direct 1,3-intramolecular proton shift to give 6 at room temperature in 5 min. Prolonged reaction time formed isomers 7 and 8 in a ratio of 4:1. AM1 calculations indicate that the isomer 8, which is formed as minor product, has a lower heat of formation (-99.34 kcal mol(1)) than that of the major isomer 7 (-92.05 kcal mol(1)). However, when a similar reaction was performed at 100 degreesC, the thermodynamically more stable isomer 8 was formed as the major product. Furthermore, cycloaddition reactions of these new dihydroheptalene derivatives 6 and 7 with different dienophiles have been studied. The mechanism has been discussed.