Synthesis of Pipecolic Acid-Based Spiro Bicyclic Lactam Scaffolds as β-Turn Mimics
作者:Ravindranadh V. Somu、Rodney L. Johnson
DOI:10.1021/jo050529k
日期:2005.7.1
A series of 6.5.5 spiro bicyclic lactam scaffolds were synthesized from pipecolic acid in a sequence of reactions that was initiated with the α-allylation of tert-butoxycarbonyl pipecolic acid. Oxidative cleavage of the olefin to give an aldehyde followed by condensation with d-cysteine methyl ester gave a mixture of pipecolyl thiazolidines. Cyclization of the pipecolyl thiazolidines with Mukaiyama's
在一系列的反应中,从叔丁酸合成了一系列的6.5.5螺双环内酰胺支架,该反应是由叔丁氧基羰基哌可酸的α-烯丙基化引发的。烯烃的氧化裂解得到醛,然后与d-半胱氨酸甲酯缩合,得到哌啶基噻唑烷的混合物。用Mukaiyamayama试剂环化胡椒基噻唑烷,得到螺双环内酰胺4a - d。对于在该位置具有S立体化学的那些螺双环内酰胺支架,在酸性条件下观察到7'a桥头碳的差向异构体。在6.5.5螺双环内酰胺骨架与3'小号,6' - [R,7'a R立体化学模仿了II型β-转角,而具有3 'S,6 'S,7'a R立体化学的支架模仿了右手的聚d-脯氨酸II螺旋。