SYNTHETIC METHODS .21. REGIOCHEMISTRY OF HALOGEN AZIDE ADDITION TO ALLENES
SYNTHETIC METHODS .21. REGIOCHEMISTRY OF HALOGEN AZIDE ADDITION TO ALLENES
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DOI：
10.1021/jo00364a027
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发表时间：
1986-07-11
影响因子：
3.6
通讯作者：
KEOGH, J
中科院分区：
文献类型：
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作者：
HASSNER, A;KEOGH, J
碘叠氮化物被发现进行单加成到烷基取代的烯8-11，产生区域选择性烯丙基叠氮化物，可以进行[3，3]-重排。Aliene本身是一个例外，它在室温下加入IN 3形成双加合物，显示出具有偕-二叠氮化物结构，并衍生自乙烯基叠氮化物单加合物。BrN 3在-65 ℃下倾向于表现为类似于IN 3的离子试剂，但在室温下，它以自由基方式与异烯加成，导致不稳定的双加合物，并且可以爆炸性地分解。这些实验室以前的工作表明，卤代叠氮化物通常区域和立体选择性地加成到烯烃上，导致加成物是许多功能基团以及小环和大环杂环的有用前体。2用这些试剂研究aliene底物不仅从定义区域化学和机械因素3的角度，而且作为潜在的合成亚甲基氮杂环丙烷和亚甲基氮杂环丙烷的途径，都是有意义的。4例如，卤素叠氮化物XN 3与丙二烯1的离子加成，如果类似于Br 2与该底物的加成，5应产生3，其可能是丙二烯叠氮化物4的前体，因此是亚甲基庚二烯5的前体。另一方面，XN 3与1的自由基加成可产生2，其作为烯丙基卤化物预期通过还原或用膦6处理转化为亚甲基氮丙啶6。由于我们已经表明，IN 3通常通过三元碘鎓离子中间体7加成到烯烃上，而BrN 3可以以离子或自由基的方式加成，后者受到非极性溶剂的青睐，我们决定研究这些卤代叠氮化物对某些异烯烃的行为。
Iodine azide was found to undergo monoaddition to alkyl-substituted alienes 8-11, producing regioselectively allyl azides that can undergo [3, 3]-rearrangement. Aliene itself is an exception and adds IN3 at room temperature to form a bisadduct, shown to have a gem-diazide structure and to be derived from a vinyl azide monoadduct. BrN3 tends to behave as an ionic reagent analogous to IN3 at-65 C, but at room temperature it adds to alienes in a free radical manner, leading to bisadducts which are unstable and can decompose explosively. The chemistry of the adducts was briefly explored.Previous work in these laboratories has shown that halogen azides usually add regio-and stereoselectively to alkenes, leading to adducts that are useful precursors to many functioned groups as well as to small and larger ring heterocycles. 2 A study of aliene substrates with these reagents is of interestnot only from the point of view of defining regiochemical and mechanisticfactors3 governing such additions to cumulative double bonds but also as potential syntheticroutes to methyleneazirines and me-thyleneaziridines. 4 For instance, ionic addition of halogen azide XN3 to aliene 1, if analogous to Br2 addition to this substrate, 5 should lead to 3, which might be a precursor to allenic azide 4 and hence to methyleneazirine 5. On the other hand free radical addition of XN3 to 1 could lead to 2, which as an allylic halide is expected to be converted by reduction or treatment with a phosphine6 to a methy-leneaziridine 6. Since we have shown that IN3 usually adds to olefinsvia a three-membered iodonium ion interme-diate, 7 while BrN3 can add either in an ionic or a free radical fashion, the latter being favored by nonpolar sol-vents, 21’we decided to examine the behavior of these halogen azides toward some alienes.