A peculiar transition-metal-free cyclodimerization of propargylic alcohols to vinyl bicyclic ketals
摘要:
Propargylic alcohols, alkylaryl(hetaryl)ethynyl carbinols, under transition-metal-free conditions (KOH/DMSO, 70-80 degrees C, 10-15 min) unexpectedly undergo stereoselective cyclodimerization to 7-methylene-6,8-dioxabicyclo[3.2.1]octanes having the scaffold of known insect pheromones and marine toxins. Under acetylenic pressure the yields of bicyclic ketals reach 80%. In all the cases, the cyclodimers are formed exclusively as one diastereomer. (C) 2011 Elsevier Ltd. All rights reserved.
the starting bicyclooctanes. Sulfur derivatives of 6,8-dioxabicyclo[3.2.1]octanes related to a number of natural products have been synthesized by the click hydrothiolation (AIBN or UV irradiation) of 7-methylene-6,8-dioxabicyclo[3.2.1]octanes, assembled from acetylene and ketones in a one-pot transition-metal-free synthetic operation. An unusual feature of this free-radical reaction is that it is
Superbase-Promoted Selective Cascade Cyclization Reaction of 1,5-Diketones with Acetylenes to Methylene-6,8-dioxabicyclo[3.2.1]octanes
作者:Elena Yu. Schmidt、Ivan A. Bidusenko、Nadezhda I. Protsuk、Igor A. Ushakov、Boris A. Trofimov
DOI:10.1002/ejoc.201201700
日期:2013.4
1,5-Diketones are readily cyclized in the presence of various alkali-metal superbases with acetylenes at 70 °C in a one-pot cascade reaction to give methylene-6,8-dioxabicyclo[3.2.1]octanes in up to 92 % yield. In the case of symmetrical 1,5-diketones, only one diastereomer is formed, whereas unsymmetrical diketones afford two diastereomers in a ratio corresponding to that of the starting ketones.
1,5-二酮在各种碱金属超强碱存在下与乙炔在 70 °C 的一锅级联反应中很容易环化,得到高达 92% 的亚甲基-6,8-二氧杂双环 [3.2.1] 辛烷屈服。在对称的 1,5-二酮的情况下,仅形成一种非对映异构体,而不对称的二酮以对应于起始酮的比例提供两种非对映异构体。该结果表明关键的级联环化序列是立体选择性的。
Synthesis of Functionalized 3,4-Dihydropyrans via Rearrangement of the Products of a One-Pot Diastereoselective Assembly of Ketones and Acetylene
作者:Elena Yu. Schmidt、Boris A. Trofimov、Nadezhda V. Zorina、Albina I. Mikhaleva、Igor A. Ushakov、Elena V. Skital'tseva、Olga N. Kazheva、Grigorii G. Alexandrov、Oleg A. Dyachenko
DOI:10.1002/ejoc.201001229
日期:2010.12
The products of the one-pot assembly of ketones and acetylene, 7-methylene-6,8-dioxabicyclo[3.2.1]octanes, congeners of an insect pheromone frontalin, undergo an acid-catalyzedrearrangement to diastereomerically pure 2-acetyl-3,4-dihydropyrans in excellent yields. The synthesis is realizable in a one-pot manner procedure directly from ketones and acetylene.
Acetylene-based two-step diastereoselective synthesis of bridgehead dihydro-oxadiazines using ketones and hydrazine as the only reactants
作者:Elena Yu. Schmidt、Nadezhda V. Semenova、Elena V. Ivanova、Inna V. Tatarinova、Igor’ A. Ushakov、Alexander V. Vashchenko、Boris A. Trofimov
DOI:10.1039/c9cc00315k
日期:——
4-oxadiazines are synthesized in up to 94% yield by the acid-catalyzed diastereoselective reaction of hydrazine hydrate with 6,8-dioxabicyclo[3.2.1]octanes (6,8-DOBCOs), the products of the superbase-promoted self-organization of acetylene with ketones. The synthesis covers a diverse range of alkylaromatic ketones having F-, Cl-, Br-, alkoxy-, CF3- and aryl substituents in different positions of the aromatic
Alkanethiol-promoted stereoselective radical rearrangement of 7-methylidene-6,8-dioxabicyclo[3.2.1]octanes to 2-acetyl-3,4-dihydropyrans
作者:B. A. Trofimov、E. Yu. Schmidt、I. A. Bidusenko、N. A. Cherimichkina
DOI:10.1134/s1070428016070253
日期:2016.7
structural analogs of insect pheromones [2, 3] and mammalian hormones [4, 5]. This one-pot transformation of simple and readily accessible reagents to complex functionalized heterocyclic systems combining bicyclic acetal and vinylether moieties in a single molecule opens unexpected prospects for the development of organic synthesis where the synthon (building block) approach is now increasingly used for the