Radical cyclisation of the vinyl ether bromides (2) and (7) in the presence of tri-n-butylstannane produces precursors [ (3) and (8)] to the β-oxy-γ-butyrolactones (6) and (9) in high yields (80°). By contrast, treatment of (2) and (7) with -(dimethylglyoximato)(pyridine)cobalt(I) chloride followed by oxidation of the intermediates (5) and (11) led to the corresponding β-oxy-γ-butyrolactones (4) and
在三正
丁基锡烷的存在下,
乙烯基醚
溴化物(2)和(7)的自由基环化产生β-氧基-
γ-丁内酯(6)和(9)的前体[ (3)和(8)]。高产(80°)。相比之下,用(二甲基乙二酰
肟基)(
吡啶)
钴(I)
氯化物处理(2)和(7),然后氧化中间体(5)和(11),得到相应的β-氧基-
γ-丁内酯( 4)和(12)。