Carbonylation of Alkynyl Epoxides: Synthesis of 5-Hydroxy-2,3-dienoate Esters and 2,3-Dihydrofuran-3-ol Derivatives
摘要:
The carbonylation of alkynyl oxiranes catalyzed by (MePh2)(4)Pd in the presence of 20 atm of carbon monoxide in methanol gives methyl 5-hydroxy-2,3-pentadienoates in good yields. When the reaction is performed on alkynyl oxiranemethanol derivatives, 4,5-dihydrofuran-3-ol derivatives are obtained stereoselectively. These products arise from the spontaneous cyclization of a dihydroxyallenyl ester intermediate.
Simultaneous Synthesis of Both Rings of Chromenes via a Benzannulation/<i>o</i>-Quinone Methide Formation/Electrocyclization Cascade
作者:Nilanjana Majumdar、Keith A. Korthals、William D. Wulff
DOI:10.1021/ja210655g
日期:2012.1.18
A new route to the chromene ring system has been developed which involves the reaction of an α,β-unsaturated Fischer carbenecomplex of chromium with a propargyl ether bearing an alkenyl group on the propargylic carbon. This transformation involves a cascade of reactions that begins with a benzannulation reaction and is followed by the formation of an o-quinone methide, and finally results in the emergence
开发了一种色烯环体系的新路线,该路线涉及铬的α,β-不饱和费歇尔卡宾络合物与在炔丙碳上带有烯基的炔丙醚的反应。这种转化涉及一系列反应,从苯并环化反应开始,然后形成邻醌甲基化物,最后在电环化时产生色烯。通过使用芳基卡宾络合物,该反应被扩展以提供通路。这是色烯的首次合成,其中色烯系统的两个环均在一步中生成,并在 lapachenole 和维生素 E 的合成中得到突出体现。
Rh-Catalyzed [5+1] and [4+1] Cycloaddition Reactions of 1,4-Enyne Esters with CO: A Shortcut to Functionalized Resorcinols and Cyclopentenones
novel Rh‐catalyzed [n+1]‐type cycloadditions of 1,4‐enyne esters, which involve an acyloxy migration as a key step. The efficient preparation of functionalized resorcinols, including biaryl derivatives, from readily available 1,4‐enyne esters and CO was achieved by Rh‐catalyzed [5+1] cycloaddition accompanied by 1,2‐acyloxy migration. When enyne esters had an internal alkyne moiety, the reaction proceeded
我们开发了新颖的1,4-烯炔酯的Rh催化[ n +1]型环加成反应,其中涉及酰氧基迁移是关键步骤。通过Rh催化的[5 + 1]环加成并伴有1,2-酰氧基迁移,可以从容易获得的1,4-烯炔酯和CO中有效制备功能化间苯二酚,包括联芳基衍生物。当烯炔酯具有一个内部炔烃部分时,该反应会通过[4 + 1]型环加成反应进行,涉及1,3-酰氧基迁移,从而生成环戊烯酮。
Palladium-catalysed heteroannulation of acetylenic compounds: a facile method for the synthesis of benzofurans
作者:Nitya G. Kundu、Manojit Pal、Jyan S. Mahanty、Swapan K. Dasgupta
DOI:10.1039/c39920000041
日期:——
A convenient and general method for the synthesis of benzofurans from o-iodophenol and acetylenic compounds under palladium-catalysed conditions is described.
carbonylative cycloadditionreaction has been developed using a Rh complex as catalyst. This reaction can convert readily available 3-acyloxy-1,4-enynes and CO to a wide range of functionalized resorcinols in good yields. A mechanism involving Rh-catalyzed cyclocarbonylation of 3-acyloxy-1,4-enynes accompanied by a 1,2-acyloxy shift is proposed for the present [5+1] type cycloadditionreaction.
Palladium-catalysed heteroannulation with acetylenic compounds: synthesis of benzofurans1
作者:Nitya G. Kundu、Manojit Pal、Jyan S. Mahanty、Mahuya De
DOI:10.1039/a703305b
日期:——
A detailed study of the heteroannulation of o-iodophenol with acetylenic substrates through palladium–copper catalysis leading to the synthesis of the 2-substituted benzofurans 21–29 is reported. An acylic compound 30 has been isolated and proved to be an intermediate in the synthesis of the benzofurans. Some of the benzofurans have been transformed into biologically active compounds.