Method for preparing alpha-alkylated ketone by coupling alcohol with alpha-methyl/methylene ketone

Abstract

The invention relates to a method for preparing alpha-alkylated ketone by coupling alcohol with alpha-methyl / methylene ketone. The method comprises the following steps: sequentially adding alpha-methyl / methylene ketone compounds and alcohol compounds into a reaction solvent, then, adding 2mol% of catalyst bistriphenylphosphine rhodium carbonyl chloride (RhCl (CO) (PPh3) 2), finally adding an inorganic alkali, and reacting at 50-100 DEG C to obtain reaction liquid after the reaction is completed; and filtering, concentrating and column chromatography separating the reaction liquid according to a conventional method to obtain the alpha-alkylated ketone. The method provided by the invention is efficient, rapid and environmental-friendly.

Description

technical field [0001] The invention relates to α-alkyl ketones in the field of organic synthetic chemistry, in particular to a method for preparing α-alkylated ketones by coupling alcohols with α-methyl / methylene ketones. Background technique [0002] The coupling reaction of α-methyl ketones with alcohols is an important pathway for C-C bond formation. It has been widely concerned for a long time, and transition metal-catalyzed alcohols as alkylating reagents are the focus of attention of chemists from all over the world in the research of organic synthesis! This kind of reaction not only has a high atom utilization rate, but also the by-product is water, which has no pollution to the environment and is green and environmentally friendly. At present, many achievements have been made in the coupling reaction of α-methyl ketone and alcohol. Studies on such reactions have been reported for a long time, but there are certain limitations. In 2002, the Cho group used RuCl 2 ...

AI Technical Summary

Problems solved by technology

Studies on such reactions have been reported for a long time, but there are certain limitations

In 2002, Cho's group used RuCl2(PPh3) (Tetrahedron Letters 2002, 43, 7987–7989) as a catalyst to synthesize α-alkyl ketones, but the reaction It is necessary to add a hydrogen acceptor such as dodecene or decene; in 2005, they used Pd / C (Journal of Molecular Catalysis A: Chemical 240 (2005) 55–60) as a catalyst to synthesize α-alkyl ketone, but the reaction needs 40h to complete; in 2003, the Ishii group used [Ir(cod)Cl]2 / PPh3 (J. Am. Chem. Soc . 2004, 126,72-73) as a catalyst also synthesized the substance, but the reaction requires nitrogen protection; in 2008, the Yus group used Ni NPs (Eur. J. Org. Chem. 2008, 4908–4914) as a catalyst, The compound was also synthesized, but in this reaction, a part of the reduction product was generated; in 2012, the Ryu group used RuHCl(CO)(PPh3)3 (Org. Lett. 2012, 14, 4703-4705) as a catalyst, Cs2CO3 as a base, also efficiently synthesized α-alkyl ketones, but the reaction temperature was higher , requires 140°C

As can be seen from the above method, the previous method has the following problems: (1) need to add hydrogen acceptor; (2) long reaction time; (3) reaction needs nitrogen protection; (4) complex reaction product; (5) relatively high reaction temperature