Very short highly enantioselective Grignard synthesis of 2,2-disubstituted tetrahydrofurans and tetrahydropyrans
作者:Claudio Monasterolo、Helge Müller-Bunz、Declan G. Gilheany
DOI:10.1039/c9sc00978g
日期:——
synthesis of tertiary alcohols. In turn this enables the simple, short and highly enantioselective (up to 96% ee) preparation of chiral 2,2-disubstituted THFs and THPs. Thus, asymmetric addition of Grignard reagents to γ-chlorobutyrophenones and δ-chlorovalerophenones takes place in the presence of a chiral diaminocyclohexyl-derived tridentate ligand and subsequent base-promoted intramolecular cyclisation
具有细长链的苯酚是配体促进的不对称格利雅(Grignard)叔醇合成的优良底物。反过来,这可以实现简单,短暂和高度对映选择性(ee高达96%)制备手性2,2-二取代的THF和THP。因此,在存在手性二氨基环己基衍生的三齿配体的情况下,将格氏试剂不对称地添加到γ-氯代丁酮和δ-氯代戊烯酮中,随后发生碱基促进的分子内环化反应,并完全保留了不对称性。作为方法学的例子,我们报道了棉酚,γ-乙基-γ-苯基丁内酯和δ-甲基-δ-甲苯基戊内酯的最短合成,波维尼安A的联合最短且灵活的合成以及波维尼安B和yingzhaosu的最短形式合成C。