共查询到17条相似文献,搜索用时 125 毫秒
1.
报道了一种简便、有效的水相嚬呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中,用金属锌促进羰基化合物进行水相嚬呐偶合反应,其中加入的少量季铵盐或季磷盐有助于显著提高反应产率,嚬呐醇产率由53%提高到87%。但嚬呐偶合反应的产率受羰基周围环境的立体位阻影响较大,在此条件下,金属锌可有效地促进芳香族醛化合物进行水相嚬呐偶合反应,得到产率较高的嚬呐醇,但非对映异构体选择性差,而脂肪族醛化合物得到的嚬呐醇产率较低,在同样条件下,酮类化合物不能顺利进行嚬呐偶合反应。 相似文献
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传统的呐偶合反应必须在无水有机溶剂条件下, 由金属或金属化合物促进羰基化合物进行呐偶合反应. 曾经报道过金属锌在强碱介质或弱酸介质中, 促进羰基化合物进行水相呐偶合反应. 本文报道一种简便、有效的水相呐偶合反应, 它是在含有少量冠醚的稀氨水溶液中, 使用锌粉促进醛基化合物进行水相呐偶合反应, 其中加入少量的冠醚有助于提高反应的产率, 呐醇产率由63%提高到84%. 然而, 呐偶合反应的产率受到羰基周围环境的立体位阻影响较大, 在此条件下, 锌粉能有效地促进芳香族醛类化合物进行水相呐偶合反应, 得到的呐醇产率高, 但非对映异构体选择性差, 而脂肪族醛类化合物得到的呐醇产率较低, 在同样的条件下, 酮类化合物不能顺利进行呐偶合反应. 相似文献
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传统的(口片)呐偶合反应必须在无水有机溶剂条件下,由金属或金属化合物促进羰基化合物进行(口片)呐偶合反应.曾经报道过金属锌在强碱介质或弱酸介质中,促进羰基化合物进行水相(口片)呐偶合反应.本文报道一种简便、有效的水相(口片)呐偶合反应,它是在含有少量冠醚的稀氨水溶液中,使用锌粉促进醛基化合物进行水相(口片)呐偶合反应,其中加入少量的冠醚有助于提高反应的产率,(口片)呐醇产率由63%提高到84%.然而,(口片)呐偶合反应的产率受到羰基周围环境的立体位阻影响较大,在此条件下,锌粉能有效地促进芳香族醛类化合物进行水相(口片)呐偶合反应,得到的(口片)呐醇产率高,但非对映异构体选择性差,而脂肪族醛类化合物得到的(口片)呐醇产率较低,在同样的条件下,酮类化合物不能顺利进行(口片)呐偶合反应. 相似文献
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氮气保护条件下,纳米铝在0.1 N NH4Cl溶液中,能有效地促进羰基化合物与烯丙基溴进行Barbier-Grignard型烯丙基化反应,得到相应高烯丙醇。芳香族醛或酮的烯丙基化产率较高,而脂肪族羰基化合物反应产率低,反应产率受羰基空间位阻影响大,在同样条件下,邻羟基羰基化合物烯丙基化产物主要是赤式-邻二醇。 相似文献
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报道了2mol/L的盐酸水溶液中锌粉促进芳香族羰基化合物的Pian呐醇偶联。该 反应条件温和、操作简便、产率高。 相似文献
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在三乙胺存在下,鉮盐与苯硫基氯化物反应,然后与醛反应,产生相应的α-苯硫基-α,β-不饱和羰基化合物,构型以(Z)-型为主,产率良好. 相似文献
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以水为反应介质、NBS为氧化剂,在水相无催化剂条件下实现了醇的氧化.芳香醇、脂肪醇都可以达到95%以上的醛(或酮)产率,但该体系对一些含供电子取代基的醇的反应活性不高,选用salen-Co(Ⅲ)配合物作为催化剂,可拓宽反应的底物适用范围. 相似文献
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A simple and effective pinacol coupling of various aromatic aldehydes mediated by gallium in good yields has been carried out. The reaction is highly effective in water in the prurience of KOH or HCl and was strongly affected by the steric environ-ment surrounding the carbonyl group. Aliphaflc aldehydes, ke-tones and aromatic ketones appear inert under the same reac-tion conditions. 相似文献
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In the presence of a catalytic amount of iodine, metallic samarium mediated pinacol coupling of carbonyl compounds has been carried out under saturated aqueous NH4Cl-THF conditions at room temperature. It gives corresponding 1,2-diols in good yields. 相似文献
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A convenient pinacol coupling of aromatic aldehydes and aryl methyl ketones has been achieved with high yields by aluminum powder in the presence of oxalic acid in water. However, the diastereoselectivities of pinacols were not satisfying, and most aliphatic aldehydes and diaryl ketones have been found to be unreactive under the same conditions. 相似文献
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Room temperature-stable inorganic electride [Ca(24)Al(28)O(68)](4+)4e(-) was employed for a pinacol coupling reaction in aqueous media. Ca-Al-O gel formed by the destruction of the crystal structure of an electride by water media played a key role in transferring the electron to electrophilic aldehydes. Aromatic aldehydes reacted smoothly with moderate to high yields. 相似文献
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Asymmetric pinacol coupling of aromatic aldehydes with TiCl2/enantiopure amine or hydrazine reagents
《Tetrahedron: Asymmetry》2000,11(19):3861-3865
Asymmetric pinacol coupling of aromatic aldehydes under homogeneous conditions with TiCl2 in the presence of enantiopure amines or hydrazines afforded 1,2-diols in moderate to excellent yields with good dl-diastereoselectivities and enantioselectivities in the range of 6–65% ee. A non-linear temperature effect (‘principle of isoinversion’) has been examined. 相似文献
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Jiangtao Sun Zhenya Dai Changsi Li Xu Pan Chengjian Zhu 《Journal of organometallic chemistry》2009,694(20):3219-3221
The asymmetric pinacol coupling of aromatic aldehydes by chiral salan–vanadium complexes as effective catalysts is reported. Chiral 1,2-diols were obtained with high diastereoselectivities (up to 90/10) and moderate to high enantioselectivities (up to 82% ee). The possible mechanism of the pinacol coupling reaction is also discussed. 相似文献