Enantioselective synthesis of axially chiral 1-(1-naphthyl)isoquinolines and 2-(1-naphthyl)pyridines through sulfoxide ligand coupling reactions
作者:Robert W. Baker、Simon O. Rea、Melvyn V. Sargent、Elisabeth M.C. Schenkelaars、Tjitjik Srie Tjahjandarie、Angela Totaro
DOI:10.1016/j.tet.2005.02.008
日期:2005.4
coupling reactions of (R)-(+)- and (S)-(−)-2-[(4′-methylphenyl)sulfinyl]-3-methylpyridines, (R)-(+)-17 and (S)-(−)-17, with 2-methoxy-1-naphthylmagnesium bromide providing (−)- and (+)-2-(2′-methoxy-1′-naphthyl)-3-methylpyridines, (−)-18 and (+)-18, in 53 and 60% ee, respectively. The free energy barriers to internal rotation in 3b and 18 have been determined, and the isoquinoline (R)-(−)-12 examined as a
外消旋1-(1'-异喹啉基)-2-萘甲醇rac - 12是通过外消旋1-(叔丁基亚磺酰基)异喹啉rac - 7与1-萘格氏试剂10的配体偶联反应制备的。的分辨率外消旋- 12通过野老-内半缩醛衍生物的色谱分离来实现14和15,提供(- [R )- ( - ) - 12 > 99%ee的和(的小号(+) - - ) 12 90%ee的。光学富集亚砜(S)-(-)- 7的配体偶联反应。(62%ee)与Grignard试剂10一起提供了rac - 12,没有由于亚砜7竞争性快速消旋而导致的立体诱导。旋光富集的(S)-(-)- 7与2-甲氧基-1-萘基溴化镁的反应还伴随着亚砜7的外消旋化,并提供了旋光性(+)-1-(2'-甲氧基-1' -萘基)异喹啉(+)- 3b,对映体纯度低(ee为14%)。(+)- 3b的绝对构型分配为R使用圆二色光谱法,基于Bijvoet方法校正了较早的分配,但是没有重原子