Alkylation

About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.

Iron-Catalyzed Carbometalation of Propargylic and Homopropargylic Alcohols

Abstract: Nucleophilic addition to alkynes represents an attractive approach to the synthesis of olefins. Obstacles to this strategy include the low reactivity of alkynes toward many organometallic reagents and difficulties associated with controlling the regioselectivity of addition. Here we demonstrate that Fe(III) salts are effective precatalysts for the carbometalation of alkynes. Primary and secondary propargylic and homopropargylic alcohols react with alkyl and aryl Grignard reagents to provide Z-allylic and -homoallylic alcohols as single stereo and regioisomers. Alkylation and arylation occur distal to the alcohol. Common oxygen protecting groups and tertiary nitrogens are tolerated. The intermediate vinyl magnesium or iron species can be trapped with a variety of electrophiles including aldehydes, allyl bromide, and N-bromosuccinimide. Diyne substrates undergo an unusual addition/cyclization reaction to generate cyclic dienes. A brief discussion of mechanism is included.

Synthesis of ketones from biomass-derived feedstock.

Abstract: Cyclohexanone and its derivatives are very important chemicals, which are currently produced mainly by oxidation of cyclohexane or alkylcyclohexane, hydrogenation of phenols, and alkylation of cyclohexanone. Here we report that bromide salt-modified Pd/C in H2O/CH2Cl2 can efficiently catalyse the transformation of aromatic ethers, which can be derived from biomass, to cyclohexanone and its derivatives via hydrogenation and hydrolysis processes. The yield of cyclohexanone from anisole can reach 96%, and the yields of cyclohexanone derivatives produced from the aromatic ethers, which can be extracted from plants or derived from lignin, are also satisfactory. Detailed study shows that the Pd, bromide salt and H2O/CH2Cl2 work cooperatively to promote the desired reaction and inhibit the side reaction. Thus high yields of desired products can be obtained. This work opens the way for production of ketones from aromatic ethers that can be derived from biomass. Conversion of biomass-derived chemicals to industrially relevant products can allow sustainable production of organic compounds. Here the authors report that aromatic ethers, which can be derived for biomass, can be converted into various cyclohexanones via a bromide salt-modified palladium catalyst.