221482-76-4Relevant academic research and scientific papers
Diastereoselective Diels-Alder reaction of 2-(α,β-unsaturated)acyl-3- phenyl-1-menthopyrazoles
Kashima, Choji,Fukusaka, Kiyoshi,Takahashi, Katsumi,Yokoyama, Yukihiro
, p. 1108 - 1114 (1999)
The reaction of 2-(α,β-unsaturated)acyl-3-phenyl-1-menthopyrazoles (9) with dienes gave Diels-Alder adducts in good yield. The addition of MgBr2 · OEt2 or ZnCl2 accelerated these reactions through the formation of chelating bonds such as N ··· Mg ··· O=C or N ··· Zn ··· O=C. The structural fixation by these catalysts also promoted the endo and diastereoselectivities of the Diels-Alder addition on the Re-face of the dienophiles. These results were supported by PM3 calculations, in which the heats of formation of the transition states anticipated the remarkable differences between the Re- and Si-facial attacks of the dienes.
