作者:Ruben Bartholomäus、Janina Bachmann、Christian Mang、Lars Ole Haustedt、Klaus Harms、Ulrich Koert
DOI:10.1002/ejoc.201201279
日期:2013.1
A synthesis of the AB-ring substructure of granaticin A was developed. The pyranolactone moiety was stereoselectively accessed by Sharpless asymmetric dihydroxylation and subsequent oxa-Pictet–Spengler cyclization. The use of BF3·OEt2 resulted in the formation of the cis pyranolactone, whereas the combination of BF3·OEt2 with trifluoroacetic acid led to the trans isomer. The resulting hydroquinones
开发了granaticin A的AB环亚结构的合成。通过 Sharpless 不对称二羟基化和随后的 oxa-Pictet-Spengler 环化,可以立体选择性地获得吡喃内酯部分。BF3·OEt2 的使用导致了顺式吡喃内酯的形成,而BF3·OEt2 与三氟乙酸的结合导致了反式异构体的形成。所得氢醌通过臭氧分解选择性裂解为二羧酸。芳基格氏试剂可以区域选择性地添加到不对称酸酐中。作为构建 B 环的替代策略,可以建立苯-呋喃环加成反应。