Nucleophilic additions toN-glycosylnitrones part IV Asymmetric synthesis ofN-hydroxy-?-aminophosphonic and ?-aminophosphonic acids
作者:Rolf Huber、Andrea Vasella
DOI:10.1002/hlca.19870700603
日期:1987.9.23
proved inert towards the phosphite anions, they reacted with P(OSiMe3)3 under catalysis by Lewis acids. Thus, P(OSiMe3)3 reacted with the crystalline (Z)-N-glycosylnitrones 2 and 8 to give the optically active N-hydroxy-α-aminophosphonic acids 4 and 10, respectively, and hence the α-aminophosphonic acids 5 and 11 in yields up to 92% and with an enantiomeric excess (e.e.) up to 97% (Scheme 1). The absolute
添加亚磷酸阴离子和三(三甲基硅烷基)亚磷酸酯(P(OSiMe 3)3),以Ñ -glycosyl- Ç -arylnitrones检查。尽管这些硝酮对亚磷酸根阴离子呈惰性,但它们在路易斯酸催化下与P(OSiMe 3)3反应。因此,P(OSiMe 3)3与结晶的(Z)-N-糖基硝酮2和8反应,得到旋光的N-羟基-α-氨基膦酸4和10。因此,α-氨基膦酸5和11的产率最高为92%,对映体过量(ee)最高为97%(方案1)。膦酸酯的绝对构型取决于性质,在一种情况下取决于催化剂的量(图)。在HCIO 4或Zn(OTF)2催化下,将p(OSiMe 3)3添加到2中,在两种情况下均得到(+)-(R)-苯基磷酸甘氨酸5(光学纯度分别为79–84和90–93%)。光学纯度(op)几乎不受这些催化剂的量(0.02-; 1当量)的影响。但是,用ZnCl 2催化可得到痕量的催化剂,(-)-(S)-5(op 79%),而等摩尔量的ZnCl