Generation of α-phosphonovinyl radicals and development of a new route to highly functionalized vinylphosphonates and vinylphosphonate-incorporated carbocyclic or heterocyclic compounds via a radical trapping sequence
作者:Takafumi Ageno、Tatsuo Okauchi、Toru Minami、Masaru Ishida
DOI:10.1039/b416394j
日期:——
of synthetically useful alpha-phosphonovinyl radicals was achieved by treatment of alpha-phosphonovinyl halides with a tributyltin radical. The alpha-phosphonovinyl radicals 2a-d were trapped with electron-rich olefins and an electron-deficient olefin to produce alpha-functionalized vinylphosphonates 3a-f in 16-55% yields. The alpha-phosphonovinyl radicals 7e-g containing the YCH2CH=CH2 (Y = O, CH2,
可通过用三丁基锡自由基处理α-膦酰乙烯基卤化物来实现合成有用的α-膦酰乙烯基自由基的第一直接产生。用富含电子的烯烃和缺电子的烯烃捕获α-膦酰基基团2a-d,以16-55%的产率产生α-官能化的乙烯基膦酸酯3a-f。在β-位含有YCH2CH = CH2(Y = O,CH2,S)取代基的α-膦酰基基团7e-g提供了5-exo和6-endo环化产物5e-g和6e-g的混合物。良品率高。5-exo / 6-endo产物比率按以下β-取代基顺序增加:OCH2CH = CH2> CH2CH2CH = CH2> SCH2CH = CH2。讨论了β-取代基对环化反应的影响。在β位上带有功能基团(例如香叶基氧基,香叶基硫基和(2-环己烯-1-基)硫基)的α-膦酰基基团的自由基环化提供了5-exo,5-exo和6-endo以及顺式稠合-5,6-环环化产物分别以良好的产率在环内结合了α,β-不饱和膦酸酯单元。对