Effects of base strength on the copper-catalyzed cycloisomerization of propargylic acetates to form indolizines: A DFT study
2017
Yuan, Binfang | He, Rongxing | Shen, Wei | Li, Ming
Our calculations find that the base strength is the primary factor that controls the catalytic capability of cocatalysts CH3CN, Propargylic acetates (1a) and Et3N. In the proton-transfer process, the trend of catalytic activity increases in the order: Et3N > 1a > CH3CN, which matches well with the enhanced trend of base strength (Et3N > 1a > CH3CN). Et3N is the most appropriate for the present Cu-catalyzed cycloisomerization of propargylic acetates, which is in agreement with the experimental phenomena. Besides, our calculations give a reasonable explanation for the effects of terminal substituents (H- vs. Ph-) of alkyne on the catalytic reaction.
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