Highly stereoselective access to novel 2,2,4-substituted tetrahydrofurans by halocyclization: Practical chemoenzymatic synthesis of Sch 51048, a broad-spectrum orally active antifungal agent
作者:Anil K Saksena、Viyyoor M Girijavallabhan、Raymond G Lovey、Russell E Pike、Haiyan Wang、Ashit K Ganguly、Brian Morgan、Alexsey Zaks、Mohinder S Puar
DOI:10.1016/0040-4039(95)00143-z
日期:1995.3
A convenient synthesis of (−)-(2R)-cis-tosylate 2 is reported via stereoselective 5-exo iodocyclization of the optically active 2,2-disubstituted olefin 9a. Enzymatic desymmetrization of the homoallylic diol 4 with Novo SP435 allowed optimal pro-(S) selectivity to provide the desired (−)-(S)-monoacetate 9a. Under the irreversible reaction conditions, the presence of a bulky aryl substituent on the
的一种方便的合成( - ) - (2R) -顺式-tosylate 2报道经由光学活性的2,2-二取代的烯烃的立体选择性5 -外iodocyclization 9A。用Novo SP435对均烯丙基二醇4进行酶促脱对称可实现最佳的pro-(S)选择性,以提供所需的(-)-(S)-单乙酸酯9a。在不可逆的反应条件下,在2,2-二取代的烯烃上存在庞大的芳基取代基似乎决定了这些卤代环化反应的立体化学结果。