reaction of easily accessible 3,5‐dichloro‐2H‐1,4‐oxazin‐2‐one with 14 a as a key step. Furthermore, it is demonstrated that dehydroantofine is a promising candidate as a new antimalarial agent in a biological assay with chloroquine‐resistant Plasmodium falciparum.
通过采用新颖的区域选择性氮杂杂Diels-Alder反应(可轻松获得的3,5-二氯-2 H -1,4-恶嗪-2-1与14 a为关键步骤)实现了脱氢黄嘌呤的总合成。此外,在抗氯喹抗性恶性疟原虫的生物检测中,证明了脱氢黄嘌呤是一种有前途的候选药物,可作为一种新型抗疟药。
MEERPOEL, LIEVEN;HOORNAERT, GEORGES, SYNTHESIS,(1990) N0, C. 905-908
作者:MEERPOEL, LIEVEN、HOORNAERT, GEORGES
DOI:——
日期:——
A General Synthesis of 3,5-Dihalo-2<i>H</i>-1,4-oxazin-2-ones from Cyanohydrins
作者:Lieven Meerpoel、Georges Hoornaert
DOI:10.1055/s-1990-27049
日期:——
In a novel approach starting from O-trimethylsilyl protected or unprotected cyanohydrins and oxalyl chloride or bromide, a series of unknown 6-substituted 3,5-dihalo-2H-1,4-oxazin-2-ones were prepared. The method was shown to be efficient for various types of cyanohydrins; however cyclization was not obtained with cyanohydrins containing bulky substituents, electron-rich aryl or heteroaryl groups. A mechanism is proposed.
Cycloaddition of Olefinic Compounds to 2<i>H</i>-1,4-Oxazin-2-ones: Synthesis of 2-Oxa-5-azabicyclo[2.2.2]oct-5-en-3-ones
作者:C. Fannes、L. Meerpoel、S. Toppet、G. Hoornaert
DOI:10.1055/s-1992-26205
日期:——
The [4 + 2] cycloaddition reactions of 2H-1,4-oxazin-2-ones 5 to olefins and the generation of new 2-oxa-5-azabicyclo [2.2.2]oct-5-en-3-ones of type 6 is studied. The cycloaddition is promoted by the 5-Cl substituent in the oxazinone and can be performed with electron-poor as well as with electron-rich alkenes. The NMR data for the isolated compounds show exclusive formation of endo adducts for symmetrically disubstituted olefins; this is interpreted in terms of secondary orbital interactions and repulsion between the lactone function and both substituents in the exo-transition state. The lower endo selectivity observed for some monosubstituted alkenes is in agreement with the expected decrease of this repulsion factor. The addition of the electron poor methyl acrylate shows rather low regioselectivity but addition of other dienophiles is always highly regioselective, the ortho regioisomer being favoured.