Torquoselective Ring Opening of Fused Cyclobutenamides: Evidence for a Cis,Trans-Cyclooctadienone Intermediate

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• 作者：Xiao-Na Wang ; Elizabeth H. Krenske ; Ryne C. Johnston ; K. N. Houk ; Richard P. Hsung
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：July 16, 2014
• 年：2014
• 卷：136
• 期：28
• 页码：9802-9805
• 全文大小：398K
• ISSN：1520-5126

文摘

Electrocyclic ring opening of 4,6-fused cyclobutenamides 1 under thermal conditions leads to cis,trans-cyclooctadienones 2-E,E as transient intermediates, en route to 5,5-bicyclic products 3. Theoretical calculations predict that 4,5-fused cyclobutenamides should likewise undergo thermal ring opening, giving cis,trans-cycloheptadienones, but in this case conversion to 5,4-bicyclic products is thermodynamically disfavored, and these cyclobutenamides instead rearrange to vinyl cyclopentenones.