Cyclization Reactions of 3,4-Diazaheptatrienyl Metal Compounds. Pyridines from an Anionic Analogue of the Fischer Indole Synthesis: Experiment and Theory
作者:Tillmann Kleine、Roland Fröhlich、Birgit Wibbeling、Ernst-Ulrich Würthwein
DOI:10.1021/jo200487v
日期:2011.6.3
N′-bisalkylidene hydrazines 7a,b, 10a–c and 13, which are accessible in good to excellent yields from hydrazones 6, 9, and 12 and commercially available α,β-unsaturated carbonyl compounds, are converted into 3,4-diazaheptatrienyl anions 14a,b, 16a–c, and 18 by treatment with KO-t-Bu as base. These anionic species form pyridines 15a,b, 5,6-dihydrobenzo[h]quinolones 17a–c, and bipyridine 19 in moderate yields. We
不对称Ñ,Ñ '-bisalkylidene肼7A,7B,10A-C和13,这是在良好的从腙优异的产率接近6,9,和12和可商购的α,β不饱和羰基化合物中,被转换成3,以KO- t- Bu为碱处理的4-二氮杂庚三烯基阴离子14a,b,16a - c和18。这些阴离子形成吡啶15a,b,5,6-二氢苯并[ h ]喹诺酮17a–c和联吡啶19产量中等。我们通过量子化学计算来解释这些反应的热力学和动力学,并讨论这种多步阴离子重排,其基于具有莫比乌斯芳香族过渡结构22,N–N键裂变(25)和6- exo - trig的电环形成考虑NICS和NBO费用计算的结果,将环化(27)作为关键步骤。这个新颖的阴离子反应序列与(阳离子)费歇尔吲哚合成的机理有一个有趣的类比。前体10c和产物16c可以通过X射线衍射表征。