A Convenient Synthesis of Optically Active 5,5-Disubstituted 4-Amino- and 4-Hydroxy-2(5H)-furanones from (S)-Ketone Cyanohydrins
作者:Holger Bühler、Andreas Bayer、Franz Effenberger
DOI:10.1002/1521-3765(20000717)6:14<2564::aid-chem2564>3.0.co;2-f
日期:2000.7.17
cyclized by LHMDS to give 5,5-disubstituted (S)-4-amino-2(5H)-furanones (S)-4 and (S)-5. Different substituents (H. Me, OBn, OH) in the 3-position of the furanones were introduced by selecting the appropriate acylating agent, which in the case of benzyloxyacetyl chloride led to the novel structure type of 4-amino-3-hydroxyfuranones (S)-5. For the synthesis of 5,5-disubstituted (S)-tetronic acids (S)-8, ketone
(S)-酮氰醇(S)-2可通过使用Manihot esculenta的羟基腈裂解酶((S)-MeHNL)作为生物催化剂,通过对酮1的对映选择性HCN加成而获得。(S)-2酰化得到相应的(S)-酰氧基腈(S)-3,可通过LHMDS环化得到5,5-二取代(S)-4-氨基-2(5H)-呋喃酮(S )-4和(S)-5。通过选择合适的酰化剂,在呋喃酮的3-位引入不同的取代基(H. Me,OBn,OH),对于苄氧基乙酰氯而言,这导致了新型结构类型的4-氨基-3-羟基呋喃酮( S)-5。为了合成5,5-二取代的(S)-四氢代酸(S)-8,首先将酮氰醇(S)-2转化为相应的2-羟基酯(S)-6。将(S)-6酰化,得到2-酰氧基酯(S)-7,通过用LHMDS或LDA处理,以高收率和过量的对映异构体提供了tetronic酸(S)-8。通过苄氧基乙酰氧基衍生物(S)-8e,f的脱苄基反应,生成了新的维生素C类似