Les bis-silanes bis-propargyliques comme précurseurs de bis(vinylidène) oxanes et oxépanes
摘要:
The preparation of bis-silanes Me3SiCH2-C=C-(CH2)(n)-C=C-CH2SiMe3 (n = 1, 2) is described. These silanes allow one to prepare bis(vinylidene)oxanes when n = 1 and bis(vinylidene)oxepanes when n = 2.
Amino-propargyl silanes condense with carbonyl compounds to form imines and subsequently cyclize to form allenylidene tetrahydroquinolines. The cyclocondensations are catalyzed by a variety of Brønsted acids, among which phosphoric acids provide the highest yields. Subsequent intramolecular and intermolecular additions to the allene moiety provide complex polycyclic amines.
Syntheses of Strychnine, Norfluorocurarine, Dehydrodesacetylretuline, and Valparicine Enabled by Intramolecular Cycloadditions of Zincke Aldehydes
作者:David B. C. Martin、Lucas Q. Nguyen、Christopher D. Vanderwal
DOI:10.1021/jo2020246
日期:2012.1.6
base-mediated intramolecular Diels–Alder cycloadditions of tryptamine-derived Zincke aldehydes is described. This important complexity-generating transformation provides the tetracyclic core of many indole monoterpene alkaloids in only three steps from commercially available starting materials and played a key role in short syntheses of norfluorocurarine (five steps), dehydrodesacetylretuline (six steps), valparicine
A sequential cycloaddition strategy for the synthesis of Alsmaphorazine B traces a path through a family of Alstonia alkaloids
作者:Allen Y. Hong、Christopher D. Vanderwal
DOI:10.1016/j.tet.2016.11.004
日期:2017.7
Driven by a new biogenetic hypothesis, the first totalsynthesis of alsmaphorazine B and several related indolealkaloids has been achieved. Numerous early approaches proved unsuccessful owing to unproductive side reactivity; nevertheless, they provided important clues that guided the evolution of our strategy. Critical to our success was a major improvement in our Zincke aldehyde cycloaddition strategy
在新的生物遗传学假说的推动下,首次实现了阿司马佛嗪 B 和几种相关吲哚生物碱的全合成。由于副反应性低下,许多早期方法被证明是不成功的。尽管如此,它们还是提供了指导我们战略演变的重要线索。我们成功的关键是我们的 Zincke 醛环加成策略的重大改进,该策略允许高效地克级规模合成 akuammicine。akuammicine 的连续化学选择性氧化导致关键的氧化重排,在生成阿司马佛嗪 B的过程中也产生了几种生物遗传学相关的吲哚生物碱。
Propargyltrimethylsilanes as Allene Equivalents in Transition Metal-Catalyzed [5 + 2] Cycloadditions
作者:Paul A. Wender、Fuyuhiko Inagaki、Magnus Pfaffenbach、Matthew C. Stevens
DOI:10.1021/ol501114q
日期:2014.6.6
including metal-catalyzed [5 + 2] cycloadditions. We report herein that rhodium-catalyzed [5 + 2] cycloadditions of propargyltrimethylsilanes and vinylcyclopropanes provide, after in situ protodesilylation, a highly efficient route to formal allene cycloadducts. Propargyltrimethylsilanes function as safe, easily handled synthetic equivalents of gaseous allenes and hard-to-access monosubstituted allenes
Enantioselective synthesis of butadien-2-ylcarbinols via (silylmethyl)allenic alcohols from chromium-catalyzed additions to aldehydes utilizing chiral carbazole ligands
作者:María Durán-Galván、Shilpa A. Worlikar、Brian T. Connell
DOI:10.1016/j.tet.2010.07.065
日期:2010.9
alcohols are obtained by treatment of aldehydes with (4-bromobut-2-ynyl)trimethylsilane in the presence of a catalytic amount of CrCl3 or CrCl2. Several new tridentate bis(oxazolinyl)carbazole ligands were synthesized and evaluated as the source of chirality. The synthesis of chiral allenic alcohols can be achieved in good yields (58–88%) and enantioselectivities (55–78% ee). Allenic alcohols may be
描述了通过使用中间体(三甲基甲硅烷基)甲基烯丙醇来合成手性,非外消旋丁二烯基羰基醇。通过在催化量的CrCl 3或CrCl 2存在下用(4-溴丁-2-炔基)三甲基硅烷处理醛来获得烯丙醇。合成了几种新的三齿双(恶唑啉基)咔唑配体,并将其评估为手性来源。手性烯丙醇的合成可以实现良好的收率(58-88%)和对映选择性(55-78%ee)。可用TBAF或2 M HCl处理烯丙醇,以43-86%的收率提供所需的二烯。或者,当用N-碘代琥珀酰亚胺处理时,(三甲基甲硅烷基)甲基烯丙醇提供碘丁二烯基甲醇。