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首页> 外文期刊>Journal of the American Chemical Society >trans-RhCl(CO)(PPh_3)_2-Catalyzed Monomeric and Dimeric Cycloisomerization of Propargylic 2,3-Dienoates. Establishment of α,β-Unsaturated δ-Lactone Rings by Cyclometallation
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trans-RhCl(CO)(PPh_3)_2-Catalyzed Monomeric and Dimeric Cycloisomerization of Propargylic 2,3-Dienoates. Establishment of α,β-Unsaturated δ-Lactone Rings by Cyclometallation

机译：反式RhCl（CO）（PPh_3）_2-催化丙炔基2,3-二烯酸酯的单体和二聚环化。环金属化建立α，β-不饱和δ-内酯环

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摘要

Cyclometallation of two unsaturated carbon-carbon bonds usually requires the application of low-valent metal catalysts, which could cleave the propargylic ester linkage. Thus, it is desirable to identify a catalyst which could undergo cyclometallation without cleaving the propargylic ester linkage. In this paper, we used trans-RhCI(CO)(PPh_3)_2 to realize the cyclometallation of propargylic 2,3-dienoates. The substituents at the 4-position of allenoate moiety nicely control the reaction pathway: when the 4-position of propargylic 2,3-dienoate 1 was monosubstituted with an aryl group, the bicyclic intermediate 7 formed by the cyclometallation could highly selectively undergo carbometalation with the alkyne moiety in the second molecule of propargylic 2,3-dienoate 1 to afford metallabicyclic intermediates 8a or 8b. Subsequent reductive elimination would afford 9, which could undergo an intramolecular Diels-Alder reaction resulting in the formation of polycyclic bis(δ-lactone)-containing structures 2. The intermediate could be trapped by adding 3-methoxyprop-1-yne affording cyclization-aromatization product 4p highly selectively. If the substituent at the 4-positon of the 2,3-allenoate moiety has a β-H atom, sequential unimolecular cyclometallation/β-H elimination/reductive elimination occurs to afford cross-conjugated 5(Z)-alkylidene-4-alkenyl-5,6-dihydro-pyran-2-ones. The Z-stereochemistry of the exo double bond was determined by the cyclometallation. Some of the α,β-unsaturated δ-lactones could be easily converted to other synthetically useful compounds via reduction reaction, hydrogenation, and iodination/coupling protocol.
机译：两个不饱和碳-碳键的环金属化通常需要使用低价金属催化剂，这可能会裂解炔丙基酯键。因此，希望鉴定出可以进行环金属化而不会裂解炔丙基酯键的催化剂。在本文中，我们使用反式RhCI（CO）（PPh_3）_2来实现炔丙基2,3-二烯酸酯的环金属化。脲酸酯部分4位的取代基很好地控制了反应路径：当炔丙基2,3-二烯酸酯1的4位被芳基单取代时，由环金属化形成的双环中间体7可以高度选择性地进行碳金属化。在炔丙基2，3-二烯酸酯1的第二个分子中的炔基部分得到金属脂环中间体8a或8b。随后的还原消除将得到9，其可进行分子内Diels-Alder反应，从而形成含多环双（δ-内酯）的结构2。可通过添加3-甲氧基丙-1-炔以提供环化作用来捕集中间体。高度选择性地芳构化产品4p。如果在2,3-脲基酸酯部分的4-位上的取代基具有β-H原子，则会发生连续的单分子环金属化/β-H消除/还原消除，从而得到交叉共轭的5（Z）-亚烷基-4-烯基-5,6-二氢-吡喃-2-酮。外环双键的Z-立体化学由环金属化确定。通过还原反应，氢化和碘化/偶联方案，某些α，β-不饱和δ-内酯可以轻松转化为其他合成有用的化合物。

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  • 来源
    《Journal of the American Chemical Society》 |2007年第37期|11600-11607|共8页
  • 作者

    Xuefeng Jiang; Shengming Ma;

  • 作者单位

    Contribution from the State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, P. R. China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
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