Germanium(II)-Mediated Reductive Cross-Aldol Reaction of Bromoaldehydes with Aldehydes: NMR Studies and ab Initio Calculations
作者:Shin-ya Tanaka、Nobuo Tagashira、Kouji Chiba、Makoto Yasuda、Akio Baba
DOI:10.1021/jo800904u
日期:2008.8.1
A highly practical reductive cross-aldol reaction of α-bromoaldehydes with various aldehydes has been developed using Ge(II)Cl2 to produce aldehyde germanium(IV) aldolates, which were directly transformed to various multifunctionalized compounds. A remarkable change in stereoselectivity depended on the α-bromoaldehydes employed; secondary α-bromoaldehydes gave syn selectivities, while tertiary α-bromoaldehydes
已经开发了使用Ge(II)Cl 2来生产α-溴醛与各种醛的高度实用的还原性醛缩醛反应,可制得醛化锗(IV)醛酸酯,将其直接转化为各种多功能化合物。立体选择性的显着变化取决于所用的α-溴代醛。仲α-溴醛可产生顺式选择性,而叔α-溴醛可完成具有季碳中心的抗选择性羟醛产物的合成。NMR研究和X射线分析强烈表明,α-溴醛2h与GeCl 2反应形成了烯醇锗。-二恶烷。详细的机械研究,包括NMR分析和从头算计算,表明生成稳定的醛缩醛锗,这是由于锗(IV)的路易斯酸度极低所致。