Concise asymmetric routes to 2,2,4-trisubstituted tetrahydrofurans via chiral titanium imide enolates: Key intermediates towards synthesis of highly active azole antifungals SCH 51048 and SCH 56592
作者:Anil K Saksena、Viyyoor M Girijavallabhan、Haiyan Wang、Yi-Tsung Liu、Russel E Pike、Ashit K Ganguly
DOI:10.1016/0040-4039(96)01203-8
日期:1996.8
approaches to the key (−)-(2R)-cis-tosylate 1 and its (+)-(2S)-enantiomer 15 via generation of chiral imide enolates having a 2,2-disubstituted olefin functionality in the β-position, are described. In a “protecting group free” sequence, reaction of the titanium enolate generated from (4R)-benzyl-2-oxazolidinone derived imide 5b with s-trioxane provided a convenient intermediate 19 which could be directly
通过生成β-中具有2,2-二取代的烯烃官能度的手性酰亚胺烯醇化物,可对键(-)-(2 R)-顺式甲苯磺酸酯1及其(+)-(2S)-对映异构体15采取两种互补的方法位置,进行说明。在“无保护基”的序列中,由(4R)-苄基-2-恶唑烷酮衍生的酰亚胺5b生成的烯醇钛与s-三恶烷的反应提供了方便的中间体19,该中间体可以直接进行2,4-非对映选择性碘环化。