stereoselective technique for additions to syn-β-alkyl-β-hydroxy-α-methyl ketones is now available. The methodology is based on the conversion of the starting material into a trichlorotitanium alkoxide derivative, which is able to assume a stable cyclic arrangement exhibiting high stereofacial discrimination towards nucleophilic alkyl transfer by an appropriate organometallic species. The use of Grignard
现在可以使用一种高效的立体选择性技术来添加到合成-β-烷基-β-羟基-α-甲基酮。该方法基于将起始材料转化为三
氯钛醇盐衍
生物,该衍
生物能够呈现稳定的环状排列,对通过适当的有机
金属物质进行的亲核烷基转移表现出高度的立体面区分。
格氏试剂的使用有严重的局限性;事实上,高位阻和碱性试剂不适用于可烯醇化底物。有机
铈化合物可以避免这些缺点,因为诸如烯醇化或与
钛 (IV) 的相互作用等副过程几乎完全被抑制。该方法允许引入多种碳系统,包括伯、仲和叔烷基链,