Studies on K2CO3-Catalyzed 1,4-Addition of 1,2-Allenic Ketones with Diethyl Malonate: Controlled Selective Synthesis of β,γ-Unsaturated Enones and α-Pyrones
摘要:
The K2CO3 (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized beta,gamma-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation of beta,gamma-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only beta,gamma-unsaturated enones 3 with an immigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-beta,gamma-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of beta,gamma-unsaturated enones 3 and 4 were formed. alpha-Pyrone derivatives were synthesized via the K2CO3-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition-carbon-carbon double bond migration-lactonization process.
Efficient Synthesis of 3-Chloromethyl-2(5<i>H</i>)-furanones and 3-Chloromethyl- 5,6-dihydropyran-2-ones via the PdCl<sub>2</sub>-Catalyzed Chlorocyclocarbonylation of 2,3- or 3,4-Allenols
作者:Xin Cheng、Xuefeng Jiang、Yihua Yu、Shengming Ma
DOI:10.1021/jo8015677
日期:2008.11.21
was formed between the center carbon atom of the allene moiety and the hydroxyl oxygen, which was established by the X-ray single crystal diffraction study of gamma-lactone 3p. The highly opticallyactive 3-chloromethyl-2(5H)-furanones could be easily prepared from the readily available opticallyactive 2,3-allenols. A mechanism for this reaction was proposed.
Catalytic Asymmetric Allenylation of Malonates with the Generation of Central Chirality
作者:Qiankun Li、Chunling Fu、Shengming Ma
DOI:10.1002/anie.201204346
日期:2012.11.19
Water plays an important role in a palladium‐catalyzed allenylation of diethyl malonate with 2,3‐allenyl acetates to yield centrallychiral allenyl malonates bearing synthetically useful functional groups (see scheme). The products were formed with 92–96 % ee in the presence of a bulky, electron‐rich biphenyl ligand at room temperature.
A CONVENIENT SYNTHESIS OF α-HYDROXYALLENES BY THE REACTION OF PROPARGYL IODIDES WITH ALDEHYDES IN THE PRESENCE OF STANNOUS HALIDE
作者:Teruaki Mukaiyama、Taira Harada
DOI:10.1246/cl.1981.621
日期:1981.5.5
In the presence of stannous halide, propargyl iodides react with aldehydes in an aprotic solvent to yield α-hydroxyallenes as major products, particularly in the cases of γ-substituted propargyl iodides, along with β-hydroxyacetylenes.
A practical procedure of propargylation of aldehydes
作者:Papiya Ghosh、Angshuman Chattopadhyay
DOI:10.1016/j.tetlet.2012.07.021
日期:2012.9
An operationally simple procedure of propargylation of aldehydes in moist solvent (distilled THF) has been developed through direct addition of propargyl bromide to aldehyde substrates mediated with low valent iron or tin. The metals were spontaneously prepared in situ employing bimetal redox strategy. Using different aldehydes as substrates (3a–k) both these metal mediated reactions took place producing
Pd(0)-Catalyzed Insertion−Cyclization Reaction of 2,3-Allenols with Aryl or Alkenyl Halides. Diastereoselective Synthesis of Highly Optically Active <i>trans</i>-2,3-Disubstituted Vinylic Oxiranes
作者:Shengming Ma、Shimin Zhao
DOI:10.1021/ja9904888
日期:1999.9.1
Pd(0)-catalyzed insertion-cyclization reaction of 2,3-allenols with aryl or alkenyl halides. Diastereoselective synthesis of highly optically active trans-2,3-disubstituted vinylic oxiranes.