Abstract
An efficient and convenient procedure has been developed for the ruthenium-catalyzed [2π + 2π] cycloadditions of dimethylacetylene dicarboxylate with norbornenes. Reaction is significantly accelerated in microwave conditions, while the commonly used benzene solvent was replaced by environmentally benign tetrahydrofuran.
ACKNOWLEDGMENTS
This research was funded by grants from the Croatian Ministry of Science, Education, and Sport (Nos. 098-0982933-3218 and 098-0982933-2920) and the Croatian Academy of Arts and Sciences.
Notes
a Standard reaction conditions: DMAD (1.2 equiv), Ru catalyst (0.1 equiv), dry THF (0.5 mL), 80 °C, 1 h. Literature procedure: DMAD (2–5 equiv), Ru catalyst (0.2–0.5 equiv), dry benzene, 80 °C, 24 h, 67%.
b Variation of standard conditions.
a Standard reaction conditions: DMAD (1.2 equiv), Ru catalyst (0.1 equiv), dry THF (0.5 mL), 80 °C, 1 h.
b Variation of standard conditions.
c Literature procedure: dry benzene, 80 °C, 1–4 days.
d Yields for products 3/4/22.
e Only product 3 was obtained.