titanium carbenoid reagents (Schrock carbenes) followed by acid-induced cyclisation of the resulting enol ethers constitutes a new method for the preparation of [4.4], [4.5] and [5.5] spiroacetals (1,6-dioxaspiro[4.4]nonanes, 1,6-dioxaspiro[4.5]decanes and 1,7-dioxaspiro[5.5]undecanes, respectively, sometimes termed 5,5-, 5,6- and 6,6-spiroketals). The titanium carbenoids are easily generated from readily
内酯与功能化
钛类卡宾试剂(Schrock卡宾)进行烷基化,然后酸诱导的烯醇醚环化,构成了一种新的制备[4.4],[4.5]和[5.5]螺
缩醛(1,6-dioxaspiro [ 4.4]
壬烷,1,6-二氧杂
螺[4.5]癸烷和1,7-二氧杂螺[5.5]
十一烷,有时被称为5,5-,5,6-和6,6-螺酮。易于从容易获得的
硫缩醛中生成
钛类化合物。