Solid-Phase Synthesis of Tetrahydro-β-carbolines and Tetrahydroisoquinolines by Stereoselective IntramolecularN-Carbamyliminium Pictet–Spengler Reactions
作者:Frederik Diness、Jürgen Beyer、Morten Meldal
DOI:10.1002/chem.200600138
日期:2006.10.25
a spontaneous intramolecular Pictet-Spengler reaction with the liberated aldehyde. The reaction proceeded with a high degree of stereoselectivity affording tetrahydro-beta-carbolines with a de (de=diastereomeric excess) above 95 % and purity in the range of 90-99 %. This reaction has been extended to a range of other aromatic C-nucleophiles, including substituted indoles, benzenes, pyrene, furan, thiophenes
提出了一种固相合成三环,四环和五环化合物的方法,该化合物包含四氢β-咔啉,四氢异喹啉或类似的骨架。反应通过中间体N-氨基甲酰基亚胺离子以高立体选择性进行,该中间体仅转化为具有各种C-亲核试剂的Pictet-Spengler型产物。由氨基酸,氨基醇或2-硝基苯甲醛合成了被3-Boc-(1,3)-恶嗪烷(Box)掩盖的氨基醛。这些被掩盖的醛的氨基部分已被转化为氨基甲酸五氟苯基酯,以用作尿素前体。通过尿素形成,将结构单元掺入树脂负载的二肽的N-末端。随后用酸处理定量地释放醛。倒数第二个色氨酸残基出现,在乙酸条件下,与释放的醛发生自发的分子内Pictet-Spengler反应。反应以高度的立体选择性进行,得到四氢-β-咔啉,其de(de =非对映异构体过量)高于95%,并且纯度在90-99%的范围内。该反应已扩展到其他芳族C-亲核试剂,包括取代的吲哚,苯,pyr,呋喃,噻吩和苯并噻吩,具有相当的立