Synthetic Studies on (−)-Lemonomycin: An Efficient Asymmetric Synthesis of Lemonomycinone Amide
作者:Yan-Chao Wu、Guillaume Bernadat、Géraldine Masson、Cédric Couturier、Thierry Schlama、Jieping Zhu
DOI:10.1021/jo8027449
日期:2009.3.6
Asymmetric synthesis of lemonomycinone amide (2) was accomplished from readily accessible starting materials. Enantioselective alkylation of N-(diphenylmethylene)glycine tert-butyl ester (11) by 5-tert-butyldimethylsilyloxy-2,4-dimethoxy-3-methylbenzyl bromide (10) in the presence of Corey-Lygo’s phase transfer catalyst [O-(9)-ally-N-(9′-anthracenylmethyl) cinchonidium bromide, 0.1 equiv] afforded
柠檬霉素酰胺(2)的不对称合成是从容易获得的起始原料完成的。的对映选择性烷基化ñ - (二苯基亚甲基)甘氨酸叔丁基酯(11)由5-叔-butyldimethylsilyloxy -2,4-二甲氧基-3-甲基苄基溴(10在科里-Lygo的相转移催化剂的存在下[)O-( 9)-ally- ñ - (9'-蒽)cinchonidium溴化物,0.1当量]得到,亚胺功能的化学选择性水解(THF / H后2 O / AcOH中),取代的升-叔丁基苯基丙氨酸13收率达85%。14与苄氧基乙醛(15)的Pictet-Spengler反应以单一非对映异构体的形式提供了1,3-顺式-二取代的四氢异喹啉16的产率为85%。受阻仲胺16与氨基酸9的偶联是在精心控制的条件下完成的,以提供酰胺22,然后将其转化为半胱氨酸24。三氟甲磺酸late催化的半胱氨酸转化为α-氨基硫醚,然后由四氟硼酸银促进的分子内曼尼希反应