Stereoselective access to tubuphenylalanine and tubuvaline: improved Mn-mediated radical additions and assembly of a tubulysin tetrapeptide analog
作者:Gregory K Friestad、Koushik Banerjee、Jean-Charles Marié、Umesh Mali、Lei Yao
DOI:10.1038/ja.2016.7
日期:2016.4
N-acylhydrazones, and generates the chiral amines in high yield with complete stereocontrol. Reductive N-N bond cleavage and alcohol oxidation converted these amino alcohols into the corresponding γ-amino acids. The route to Tuv proceeded via peptide coupling with serine methyl ester, followed by a high-yielding sequence to convert the serine amide to a thiazole. Finally, peptide bond construction established
在未保护的羟基官能团存在的情况下,使用自由基加成反应已改善了微管束苯丙氨酸和微管素(Tuv)(微管溶素家族的抗有丝分裂化合物的α-取代的γ-氨基酸结构单元)的合成。关键的碳-碳键结构需要手性N-酰基hydr的C = N键将烷基碘立体选择性地由Mn介导的光解加成,并以完全的立体控制高产率地产生手性胺。还原性NN键裂解和醇氧化将这些氨基醇转化为相应的γ-氨基酸。到达Tuv的途径是通过肽与丝氨酸甲酯偶联,然后是高产序列将丝氨酸酰胺转化为噻唑。最后,肽键的构建以C末端醇类似物的形式建立了微管溶素框架。尝试氧化为C末端的羧酸盐未成功;用二肽18进行的对照实验表明环化干扰了所需的氧化过程。