Reactivity of chiral exocyclic N-acyliminium ions with aromatic derivatives
摘要:
Chiral N-acyliminium ions obtained from optically active N-[1-(phenylsulfonyl)alkyl]oxazolidin-2-ones at low temperature in the presence of titanium tetrachloride react with electron-rich aromatic compounds to afford the corresponding adducts in good yields and variable diastereoselectivities. Chemoselective cleavage of the oxazolidin-2-one ring with lithium/ammonia affords the corresponding benzylamines in enantioenriched form. The utilization of 4-benzyloxazolidin-2-one as a chiral auxiliary leads to intramolecular cyclization with exclusive formation of one diastereomer. The obtained tricyclic derivatives possess the core structure of some aza analogs of the anticancer drug podophyllotoxin. (C) 2003 Elsevier Science Ltd. All rights reserved.
N-[1-(Phenylsulfonyl)alkyl]oxazolidin-2-ones are successfully prepared by condensation of the corresponding optically active oxazolidin-2-ones with aldehydes and benzenesulfinic acid. At low temperature, in the presence of titaniumtetrachloride, these sulfones are converted into N-acyliminium ions, which react with allyltrimethylsilane with a variable degree of stereoselectivity. The best results
Reactivity of chiral exocyclic N-acyliminium ions with aromatic derivatives
作者:Tiziana Mecozzi、Marino Petrini、Roberto Profeta
DOI:10.1016/s0957-4166(03)00123-x
日期:2003.5
Chiral N-acyliminium ions obtained from optically active N-[1-(phenylsulfonyl)alkyl]oxazolidin-2-ones at low temperature in the presence of titanium tetrachloride react with electron-rich aromatic compounds to afford the corresponding adducts in good yields and variable diastereoselectivities. Chemoselective cleavage of the oxazolidin-2-one ring with lithium/ammonia affords the corresponding benzylamines in enantioenriched form. The utilization of 4-benzyloxazolidin-2-one as a chiral auxiliary leads to intramolecular cyclization with exclusive formation of one diastereomer. The obtained tricyclic derivatives possess the core structure of some aza analogs of the anticancer drug podophyllotoxin. (C) 2003 Elsevier Science Ltd. All rights reserved.