A titanoxycyclopropane as intermediate in a highly stereoselective homoaldol type addition syntheses of -substituted tetrahydrofuran derivatives
作者:Hans-Ulrich Reissig、Hiltrud Holzinger、Gabriele Glomsda
DOI:10.1016/s0040-4020(01)80140-x
日期:1989.1
Reaction of methyl 2-siloxycyclopropanecarboxylate 4 with TiCl4 provides the unique titanoxycyclpropane whose structure could be elucidated by means of NMR-spectroscopy. Its additions to aldehydes and acetophenone occur with high stereoselectivity to afford homoaldol products like . These intermediates can further be transformed to highly substituted tetrahydrofuran derivatives by activation with BF3-OEt2
2-甲硅烷氧基环丙烷甲酸甲酯4与TiCl 4的反应提供了独特的钛氧基环丙烷,其结构可以通过NMR光谱进行阐明。它在醛和苯乙酮中的加成反应具有很高的立体选择性,从而提供了类似的醛缩醛缩醛产品。通过用BF 3 -OEt 2活化并分别与HSiEt 3或甲硅烷基化的碳亲核试剂反应,可以将这些中间体进一步转化为高度取代的四氢呋喃衍生物。该取代涉及氧碳鎓离子并以优异的非对映选择性进行。