Efficient π-facial control in the ene reaction of nitrosoarene, triazolinedione, and singlet oxygen with tiglic amides of the bornane-derived sultam as chiral auxiliary:: An economical synthesis of enantiomerically pure nitrogen- and oxygen-functionalized acrylic acid derivatives

被引:33
作者
Adam, W [1 ]
Degen, HG [1 ]
Krebs, O [1 ]
Saha-Möller, CR [1 ]
机构
[1] Univ Wurzburg, Inst Organ Chem, D-97074 Wurzburg, Germany
关键词
D O I
10.1021/ja026640e
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The ene reaction of 4-nitronitrosobenzene (ArNO), N-phenyl-1,2,4-triazoline-3,5-dione (PTAD), and singlet oxygen (1O2) with the optically active tiglic-acid derivatives of Oppolzer's bornane-derived sultam affords the respective ene products regioselectively in excellent diastereoselectivity (de up to 99%) and in good yield (55-90%). The enophiles ArNO and PTAD give with the methyl-substituted substrate exclusively the like-configured ene adduct, while 1O2 leads to an 83:17 diastereomeric mixture. With the sterically more demanding isopropyl-substituted derivative even the smallest enophile 1O2 forms exclusively the like diastereomer. The high diastereoselectivity is rationalized in terms of the proper conformational alignment of the substrate and a preferred enophilic attack from the C(β)-re face of the double bond. This concept offers an efficient synthetic route to enantiomerically pure nitrogen- and oxygen-functionalized acrylic acid derivatives. Copyright © 2002 American Chemical Society.
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页码:12938 / 12939
页数:2
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