Why we were doing this chemistry
Summary of Results
The desired starting endoxide was readily available via standard
aryne (1,2) chemistry pioneered by Wittig (3). Previous attempts by
others in our laboratory failed to give the high yields of endoxides
We guessed that our magnesium might not be fresh enough to form
the Grignard reagent, and since we were not set up to sublime the
metal, we tried adding more Mg to the reaction pot in an effort to
increase the yield. However, doing so lowered the yields of the
endoxide even further!
Endoxides produced in this fashion are easily purified by
distillation and high vacuum oven drying of the resultant solid. The
volatility of starting materials made it seem likely that we simply
weren't getting formation of the Grignard reagent, but were simply
losing the starting materials through evaporation.
(1) Newman, M. S.; Dali, H. M.; Hung, W. M. J. Org. Chem. 1975,
40, 262; (2) Wolthius, E. J. Org., Chem. 1961, 2215; (3) Wittig, G.;
Pohmer, L. Ber. 1956, 89, 1334.