One-Pot Vinylation of Azlactones: Fast Access to Enantioenriched α-Vinyl Quaternary Amino Acids
作者:Massimo Serra、Eric Bernardi、Giorgio Marrubini、Lino Colombo
DOI:10.1002/ejoc.201700353
日期:2017.5.26
We report a fast one-pot protocol for the direct vinylation of azlactones [oxazol-5-(4H)-ones] by using as a key step an aldol addition with 2-(phenylselenenyl)acetaldehyde followed by dehydroxyselenation. The acid hydrolysis of the oxazolone ring gave the desired fully deprotected α-vinyl quaternary α-amino acids in almost quantitative yields. An enantioselective variant of the method was also developed
我们报告了快速的一锅协议,直接将氮杂内酯[oxazol-5-(4 H)-ones]直接乙烯基化,方法是将醛醇与2-(苯基硒烯基)乙醛加成醛,然后进行脱羟基硒化反应,这是关键步骤。恶唑酮环的酸水解以几乎定量的产率得到了所需的完全脱保护的α-乙烯基季α-氨基酸。还通过使用催化手性碱开发了该方法的对映选择性变体。使用Sharpless配体(DHQD)2 PHAL可以产生较高的总收率(62–78%),且ee值高达86%的最终季铵氨基酸。将优化方案放大为克数量不会影响产量和ee价值观。我们还证明,安装在恶唑酮环上的乙烯基部分可被用作通过Heck偶联反应连接芳基的手柄。