The synthesis of racemic cedannycin B, an antibiotic from Streptomyces sp. TP-A0456 was achieved firstly from γ- butyrolactone. The key step was a Barbier-type addition of 3-bromomethyl-5H-furan-2-one to formaldehyde...The synthesis of racemic cedannycin B, an antibiotic from Streptomyces sp. TP-A0456 was achieved firstly from γ- butyrolactone. The key step was a Barbier-type addition of 3-bromomethyl-5H-furan-2-one to formaldehyde mediated by zinc, which afforded the sole γ-addition product 4-hydroxymethyl-3-methylene-dihydrofuran-2-one. The final compound was confirmed by 1H NMR, 13C NMR and HRMS. 2009 Xiao Hua Xu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
In the presence of active metal bismuth (Bi) which was prepared from the combination of bismuth trichloride and sodium borohydride,aldehydes have been found to react with allyl bromide in aqueous media,and the corresp...In the presence of active metal bismuth (Bi) which was prepared from the combination of bismuth trichloride and sodium borohydride,aldehydes have been found to react with allyl bromide in aqueous media,and the corresponding homoallylic alcohols were obtained in excellent yields with high chemo-and stereoselectivity.展开更多
This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media. The selectivity and possible mechanism of these reactions are discussed. The yields of products...This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media. The selectivity and possible mechanism of these reactions are discussed. The yields of products for reaction of propargyl bromide are 31 similar to 71%. The ratios of allenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3. The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52 similar to 84%.展开更多
Copper was found to be able to promote the SnCl2-mediated carbonyl allylation reactions in water, giving the corresponding homoallylic alcohol products in very high yields. Detailed studies showed that the reaction co...Copper was found to be able to promote the SnCl2-mediated carbonyl allylation reactions in water, giving the corresponding homoallylic alcohol products in very high yields. Detailed studies showed that the reaction could be applied to a variety of carbonyl compounds including those with hydroxyl, amino and nitro groups. It was also found that this reaction showed good regioselectivities for some substrates. Furthermore, carefully controled ex-periments and in situ NMR measurements provided important insights into the mechanism of the newly developed reaction.展开更多
Barbier allylation and Friedel-Crafts alkylation of （un）substituted benzaldehydes, allylbromide and phenols can be combined in a one-pot process in ionic liquid （BuPyC1/SnC12·2H2O） to directly synthesize 4-（...Barbier allylation and Friedel-Crafts alkylation of （un）substituted benzaldehydes, allylbromide and phenols can be combined in a one-pot process in ionic liquid （BuPyC1/SnC12·2H2O） to directly synthesize 4-（2-hydroxyphenyl）- 4-[（un）substituted phenyl]but-1-ene compounds, which were applied to the synthesis of 4-（substituted phenyl）- chromans through intramolecular cyclization reactions.展开更多
Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent resul...Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.展开更多
基金the National Science Foundation of China(Nos.20421202,20572055)for financial support
文摘The synthesis of racemic cedannycin B, an antibiotic from Streptomyces sp. TP-A0456 was achieved firstly from γ- butyrolactone. The key step was a Barbier-type addition of 3-bromomethyl-5H-furan-2-one to formaldehyde mediated by zinc, which afforded the sole γ-addition product 4-hydroxymethyl-3-methylene-dihydrofuran-2-one. The final compound was confirmed by 1H NMR, 13C NMR and HRMS. 2009 Xiao Hua Xu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘In the presence of active metal bismuth (Bi) which was prepared from the combination of bismuth trichloride and sodium borohydride,aldehydes have been found to react with allyl bromide in aqueous media,and the corresponding homoallylic alcohols were obtained in excellent yields with high chemo-and stereoselectivity.
文摘This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media. The selectivity and possible mechanism of these reactions are discussed. The yields of products for reaction of propargyl bromide are 31 similar to 71%. The ratios of allenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3. The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52 similar to 84%.
基金Project supported by Chinese Academy of Sciences (No. KJCXZ-SW-04) and the National Natural Science Foundation of China (No. 20332020).
文摘Copper was found to be able to promote the SnCl2-mediated carbonyl allylation reactions in water, giving the corresponding homoallylic alcohol products in very high yields. Detailed studies showed that the reaction could be applied to a variety of carbonyl compounds including those with hydroxyl, amino and nitro groups. It was also found that this reaction showed good regioselectivities for some substrates. Furthermore, carefully controled ex-periments and in situ NMR measurements provided important insights into the mechanism of the newly developed reaction.
文摘Barbier allylation and Friedel-Crafts alkylation of （un）substituted benzaldehydes, allylbromide and phenols can be combined in a one-pot process in ionic liquid （BuPyC1/SnC12·2H2O） to directly synthesize 4-（2-hydroxyphenyl）- 4-[（un）substituted phenyl]but-1-ene compounds, which were applied to the synthesis of 4-（substituted phenyl）- chromans through intramolecular cyclization reactions.
基金Project supported by the National Natural Science Foundation of China (No. 20332020).
文摘Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.
