A nitrogen-containing Lewis base catalyzed highly regioselective [4 + 2] cycloaddition of allene ketones or α-methyl allene ketones with unsaturated pyrazolones has been disclosed to give the corresponding tetrahydropyrano [2,3-c] pyrazoles in moderate to good yields under mild conditions. High regioselectivity, 100% atom-economy, broad substrate scope and good functional group tolerance are attractive
已经公开了含氮的路易斯碱催化的烯丙基酮或α-
甲基烯丙基酮与不饱和
吡唑酮的高度区域选择性[4 + 2]环加成反应,在温和的条件下,以中等至良好的收率得到相应的
四氢吡喃并[2,3- c ]
吡唑情况。高区域选择性,100%原子经济性,宽泛的底物范围和良好的官能团耐受性是该方法的诱人之处,使其成为一种实用且用途广泛的转化方法。