Novel Asymmetric Synthesis of Atropisomeric 6-Aryl Pyrazinones via an Unusual Chirality Transfer Process
作者:John Tulinsky、B. Vernon Cheney、Stephen A. Mizsak、William Watt、Fusan Han、Lester A. Dolak、Thomas Judge、Ronald B. Gammill
DOI:10.1021/jo9811930
日期:1999.1.1
Cyclization of (S,S)-alpha-[(1-phenylethyl)amino]-alpha-(2-iodophenyl)acetonitrile with (COCl)(2) in toluene or chlorobenzene afforded the atropisomeric pyrazinone (aS,S) 6-(2-alpha-iodophenyl)-3,5-dichloro-1-(1-phenylethyl)-2(1H)-pyrazinone in 57% yield. With smaller ortho substituents (F, Cl, CH(3), CF(3), OCH(3)) on the aromatic ring, mixtures of atropisomers were obtained from the cyclization reaction
(S,S)-α-[(1-苯乙基)氨基]-α-(2-碘苯基)乙腈与(COCl)(2)在甲苯或氯苯中的环化反应,得到阻转异构的吡嗪酮(aS,S)6-( 2-α-碘苯基)-3,5-二氯-1-(1-苯乙基)-2(1H)-吡嗪酮,产率为57%。在芳环上具有较小的邻位取代基(F,Cl,CH(3),CF(3),OCH(3)),可以从环化反应中获得阻转异构体的混合物。制备的所有单个阻转异构体在室温下均稳定。除了邻氟取代的阻转异构体以外,所有其他在高温下都是稳定的。本文描述了吡嗪酮的立体选择性合成,并提出了一种通过有趣的手性转移形成机制。