Thermal electrocyclic ring-opening of cyclobutenes: stereoselective routes to functionalised conjugated (Z,E)- and (E,E)-2,4-dienals
作者:Falmai Binns、Roy Hayes、Stephen Ingham、Suthiweth T. Saengchantara、Ralph W. Turner、Timothy W. Wallace
DOI:10.1016/s0040-4020(01)89013-x
日期:——
The cyclobutenecarbaldehyde 12 undergoes thermal electrocyclic ring-opening at low temperature, producing the (2Z,4E)-hexadienal 13 exclusively. By contrast, unsymmetrical derivatives of cis-3-cyclobutene-1,2-dicarboxylic acid undergo ring-opening at 80–110°C with low levels of stereoselectivity, which vary according to the balance of the electronic and, to a lesser extent, the steric nature of the
所述cyclobutenecarbaldehyde 12所经历热电环开环在低温下,制造(2 Ž,4 ë)-hexadienal 13只。相比之下,顺式-3-环丁烯-1,2-二羧酸的不对称衍生物在80–110°C时会以低的立体选择性开环,这取决于电子的平衡,并且程度较小。位于再杂化碳原子上的取代基的空间性质。