The addition of organolithium reagents to pyrylium tetrafluoroborate  followed by in situ electrocyclic ring opening of the  intermediate 2H-pyrans gives the title Z,E-dienals with  high stereoselectivity.
                                    将
有机锂试剂添加到四
氟硼酸酯吡啶中,然后在原位进行中间体
2H-吡喃的电环开环反应,能够高立体选择性地生成标题中的Z,E-二烯醛。