Work

Iron-Catalyzed Carbometalation of Propargylic and Homopropargylic Alcohols

Year: 2006

Type: article

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.

Source: Journal of the American Chemical Society

DOI: 10.1021/ja0647708

Authors: Donghui Zhang, Joseph M. Ready

Institution: The University of Texas Southwestern Medical Center

Language: English

Topic: Catalytic Alkyne Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funder: National Institute of General Medical Sciences

Awards: Catalytic Synthesis of alpha-Branched Carbonyl Compounds, G5564226626