One-Carbon Chain Extension of Esters to α-Chloroketones: A Safer Route without Diazomethane
作者:Dengjin Wang、Mark D. Schwinden、Lilian Radesca、Bharat Patel、David Kronenthal、Ming-Hsing Huang、William A. Nugent
DOI:10.1021/jo035733r
日期:2004.3.1
The reaction of a variety of methyl esters with dimethylsulfoxonium methylide at 0−25 °C affords the chain-extended β-keto dimethylsulfoxonium ylides. Subsequent treatment with hydrogen chloride in THF proceeds with loss of DMSO to afford the corresponding α-chloroketones. This sequence has been utilized to convert the methyl esters of CBZ-protected alanine and valine to the anti N-protected α-amino
各种甲酯在0-25°C下与二甲基亚砜基亚甲基反应,得到链增长的β-酮基二甲基亚砜基亚烷基。随后用氯化氢的THF溶液处理,损失DMSO,得到相应的α-氯酮。该序列已被用于将CBZ保护的丙氨酸和缬氨酸的甲酯转化为抗N保护的α-氨基环氧化物,它们是重要的药物中间体。当相同的方案应用于BOC保护的苯丙氨酸甲酯时,发生差向异构化,因此需要使用反应性更高的芳基酯。这种化学方法为避免使用有毒易爆的重氮甲烷提供了一条生产α-氯酮的实用途径。