1250863-06-9Relevant academic research and scientific papers
Rearrangements of the [2+2]-cycloadducts of DDQ and 2-ethynylpyrroles
Trofimov, Boris A.,Sobenina, Lyubov N.,Stepanova, Zinaida V.,Ushakov, Igor A.,Mikhaleva, Albina I.,Tomilin, Denis N.,Kazheva, Olga N.,Alexandrov, Grigorii G.,Chekhlov, Anatolii N.,Dyachenko, Oleg A.
, p. 5028 - 5031 (2010)
The [2+2]-cycloadducts of DDQ and 2-ethynylpyrroles, upon ethanolysis (reflux, 15 min or room temperature, 4 h), rearrange from bicyclo[4.2.0] octadienediones to bicyclo[3.2.0]heptadienone- and cyclobutenyl- dihydrofuranone moieties in 55-83% yields, the former rearrangement being the major direction. Benzoquinone ring cleavage is regioselective to afford mostly bicyclo[3.2.0]heptadienone-pyrrole ensembles (85-90% selectivity) in 39-78% yields. The only exception is when the starting compounds contain an ethoxycarbonyl substituent and the pyrrole counterpart is a 4,5,6,7- tetrahydroindole fragment. In this case, the ratio of the rearrangement products is 1:1.2 in a total yield of 83%. An important feature of the dihydrofuranone pathway rearrangement is its 100% diastereoselectivity.
