.beta.-Trichlorostannyl ketones and aldehydes. Preparation and facile amine-induced dehydrostannation leading to .alpha.-methylene ketones and aldehydes
摘要:
Ring-opening reactions of siloxycyclopropanes 1 with SnCl4 take place under mild reaction conditions and site-selectively to give beta-trichlorostannyl ketones and aldehydes 3 in high yields. The beta-trichlorostannyl ketones and aldehydes thus obtained readily undergo base-induced dehydrotrichlorostannation at room temperature to give the corresponding alpha-methylene ketones and aldehydes 4. The reactions are quite general for amines, such as pyridine, triethylamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), and 1,4-diazabicyclo[2.2.2]octane (DABCO), and the yields are good to high. One-pot conversion from siloxycyclopropanes 1 to alpha-methylene ketones or aldehydes 4 by consecutive treatment of 1 with SnCl4 and TMEDA is also successful. The H-1 NMR, C-13 NMR, Sn-119 NMR, and IR spectral properties of beta-stannyl ketones and aldehydes are also reported.
The application of several 1-butyl-3-methylimidazolium (BMIM) salt ionic liquids as solvent in the α-methylenation of carbonyl compounds at room temperature is reported. The ionic liquid [BMIM][NTf2] gave a clean reaction in a short time and good yields of several α-methylene carbonyl compounds. This ionic liquid was reused without affecting the reaction rates or yields over seven runs.
Copper-Catalyzed Enantioselective Henry Reaction of Enals and Subsequent Iodocyclization: Stereoselective Construction of Chiral Azatricyclic Frameworks
作者:Yirong Zhou、Yuequan Zhu、Shaobai Yan、Yuefa Gong
DOI:10.1002/anie.201305148
日期:2013.9.23
In the frame: A cascade sequence combining an asymmetric Henryreaction and a stereoselective intramolecular iodocyclization provides direct access to an enantioenriched tricyclic hexahydrochromeno[4,3‐b]pyrrole framework (see scheme). The Henryreaction is catalyzed by copper in the presence of L1.
在框架中:级联序列结合了不对称的亨利反应和立体选择性的分子内碘环化作用,可直接进入对映体富集的三环六氢色素[4,3- b ]吡咯骨架(参见方案)。在L1存在下铜催化了亨利反应。
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。
Carbon-Carbon Bond Formation by the Use of Chloroiodomethane as a C<sub>1</sub>Unit. III. A Convenient Synthesis of the Mannich Base from Enol Silyl Ether by a Combination of Chloroiodomethane and<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-Tetramethylmethanediamine
a combination of chloroiodomethane (CH2ClI) and N,N,N′,N′-tetramethylmethanediamine (TMMD) in DMSO as the solvent at ambient temperature. The mechanism of the transformation is discussed on the basis of product analysis and 1H NMR spectral studies. The reagent system CH2ClI/TMMD also provides a convenient route to the Eschenmoser’s salt (Me2\overset+N=CH2,\overset−I).
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.