Diels–Alder reactions of alkyl-substituted dienes with acrylonitriles give good yields and endo-selectivities if catalyzed by (organo)aluminum, (organo)boron or gallium halides. The activity of these group IIIa Lewisacids in this reaction correlates with the coordination strength of their nitrile complexes, which deactivate Lewisacids sufficiently, so that the subsequently added diene partner undergoes
Fate of the Intermediate Diradicals in the Caldera: Stereochemistry of Thermal Stereomutations, (2 + 2) Cycloreversions, and (2 + 4) Ring-Enlargements of <i>cis</i>- and <i>trans</i>- 1-Cyano-2-(<i>E</i> and <i>Z</i>)-propenyl-<i>cis</i>-3,4-dideuteriocyclobutanes
作者:W. von E. Doering、Xueheng Cheng、Kyuwang Lee、Zisen Lin
DOI:10.1021/ja0206083
日期:2002.10.1
This paper addresses the decades-old problem of gaining a measure of intellectual control over the fate of the diradical intermediate in not-obviously-concerted thermalrearrangements. It focuses mainly on the stereochemistry of the thermalrearrangement of cis- and trans-1-cyano-2-trans-propenylcyclobutane to the related ring-enlarged products, 4-cyano-3-methylcyclohexenes. The complete stereochemical