氨水介质中金属锌促进醛的(口片)呐偶联反应

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.     

金属锌促进羰基化合物水相嚬呐偶合反应

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。     

金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相噤呐偶合反应。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噘呐偶合反应，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，噘呐醇产率由53％提高到87％。但噘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噘呐偶合反应，得到产率较高的噘呐醇，但非对映异构体选择性差，而脂肪族醛化合物得到的噘呐醇产率较低，在同样条件下，酮类化合物不能顺利进行噘呐偶合反应。     

不对称呐醇偶联反应新进展

综述了近年来不同催化体系的不对称合成呐醇的方法, 并总结了不同的催化效率和对映选择性的差异.     

微波辐射FeCl3催化无溶剂条件下的呐醇重排

通过微波辐射, 以FeCl3为催化剂进行无溶剂条件下的呐醇重排反应, 1 min产率可达86%～96%. 该方法具有操作简便、反应时间缩短、对环境友好等优点.     

醛酮还原偶联合成(口片)呐醇的进展

综述了由醛酮还原偶联生成(口片)呐醇的进展,引用文献71篇.     

手性方酰胺基醇钛合物诱导的芳醛的不对称呐醇偶联反应

合成了两个手性方酰胺基醇, 与TiC1₄(THF)₂-Zn形成了手性配合物, 并用来催化芳醛的不对称呐醇偶联反应, 反应取得很高的化学产率和较高的光学收率, 同时考察了芳醛结构和共还原剂对反应的化学产率和光学收率影响.     

不对称(口片)呐醇偶联反应新进展

综述了近年来不同催化体系的不对称合成呐醇的方法,并总结了不同的催化效率和对映选择性的差异.     

水溶液中锌电极诱发芳香醛的还原偶联反应

以锌片为电极芳香醛为底物在酸性条件下电合成呐醇,探讨了电流密度、反应时间、盐酸浓度对产率的影响.最佳反应条件如下:电流密度2.4A/dm2,反应时间60min,盐酸用量(5mL)2mol/L,呐醇的产率范围14%～80%.     

Negishi偶联反应的研究进展

对有机锌试剂参与的Negishi偶联反应机理进行了简要概述,并详细综述了Negishi偶联反应的研究进展,主要介绍了Pd、Ni催化剂以及新型Fe、Co催化剂参与的Negishi偶联反应。展望了新型催化剂的发展趋势。     

Pinacol Coupling Reaction of Aromatic Aldehydes Mediated by Aqueous Vanadium(II) Solution Under Ultrasound Irradiation

Pinacol coupling of aromatic aldehydes by aqueous vanadium(II) solution under ultrasound irradiation at room temperature can lead to the corresponding pinacols in 54–93% yields within 15–30 min.     

Pinacol Coupling of Aromatic Aldehydes and Ketones in Ethyl Acetate Mediated by TiCl4‐Mg

Titanium tetrachloride in ethyl acetate can be reduced by Mg powder to the corresponding low‐valent titanium complexes, which can reduce some aromatic aldehydes and ketones to the corresponding pinacols in 38–85% yields within 15–60 min at rt with stirring.     

Coupling Reaction of Carbonyl Compounds Mediated by Gallium Metal in Aqueous Media

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.     

Enantioselective Pinacol Coupling of Aromatic Aldehydes Mediated by TiCl4（THF）2／Zn with Tartaric Ester

Asymmetric pinacol coupling of aromatic aldehydes mediated by low valent titanium complexes of chiral ligands derived from natural tartaric acid provided corresponding pinacols in good yields with excellent diastereoselectivities and moderate enantioselectivities.     

Highly meso-Diastereoselective Pinacol Coupling of Aromatic Aldehydes Mediated by Al Powder/Copper Sulfate in Water

Pinacol-type coupling reaction products presenting a high meso-diastereoselectivity (the ratio dl/meso was 4/96 up to 1/99) were obtained in fair to good yields (24–69%) using several aromatic aldehydes as starting materials and aluminium powder/copper sulfate as catalysts, in water, under reflux conditions.     

Enantioselective Pinacol Coupling of Aromatic Aldehydes Induced by Chiral Titanium Complexes

The reductive coupling of carbonyl compounds catalyzed by the transition metal is an important group of carbon-carbon bond forming reaction. The pinacol coupling reaction of aldehydes is one of the most efficient methods for synthesis of vicinal diols1. L…