Addition of a Reformatsky reagent to N-anthracene-9-sulfonyl and related imines: Synthesis of protected β-amino acids
作者:Andrew J. Robinson、Peter B. Wyatt
DOI:10.1016/s0040-4020(01)81815-9
日期:1993.1
derivatives 2d. Anthracene-9-sulfonamide (6) is readily available by sulfonation and chlorination of anthracene, and condenses with aldehydes [RCHO; R = Ph, 4-FC6H4, 4-MeOC6H4, 4-NCC6H4, 2-furyl, (E)-styryl], e.g. in the presence of TiCl4/Et3N, to yield imines 7a–7f, which after addition of tert-butoxycarbonylmethylzinc bromide give protected amino acids 8a–8f; however, 8f cyclizes to the sultam 9via a spontaneous
Reformatsky试剂叔丁氧基羰基甲基溴化锌可通过苯甲醛二甲基乙缩醛与甲磺酰胺,甲苯-4-磺酰胺,4-(甲氧基羰基)苯磺酰胺和磺酰胺缩合生成的N-磺酰亚胺类化合物,例如1a-1d,可提高收率。β-氨基酸2a–2d。对于2b和2c,N-脱保护以还原性(Na-萘;低产率)发生,或者对于磺酰胺衍生物2d以水解方式(回流吡啶水溶液;在叔丁酯酸水解后氨基酸3a的产率为76%)发生。蒽9-磺酰胺(6)很容易通过蒽的磺化和氯化得到,并与醛缩合[RCHO; R = PH,4-FC 6 H ^ 4,4-MeOC 6 H ^ 4,4-NCC 6 ħ 4,2-呋喃基,(ë) -苯乙烯基],例如在的TiCl存在4 / ET 3 N,到屈服亚胺7a-7f,在加入叔丁氧基羰基甲基溴化锌后,得到保护的氨基酸8a-8f;然而,8F环化到磺内酰胺9经由自发的分子内Diels-Alder反应。N-蒽-9-磺酰基的还原裂解