Titanium isopropoxide-mediated cis-selective synthesis of 3,4-substituted butyrolactones from CO2
Aleksi Sahari1, Cuong Dat Do2, Jere K Mannisto1
1Department of Chemistry, University of Helsinki, FI-00014 University of Helsinki, Finland. timo.repo@helsinki.fi.
Abstract:
We report a Ti(OiPr)4-mediated multicomponent reaction, which produces 3,4-substituted cis-δ-lactones from alkyl magnesium chloride, benzaldehyde and CO2. The key intermediate, titanacyclopropane, is formed in situ from Ti(OiPr)4 and a Grignard reagent, which enables 1,2-dinucleophilic reactivity that is used to insert carbon dioxide and an aldehyde. An alternative reaction route is also described where a primary alkene is used to create the titanacyclopropane. A computational analysis of the elementary steps shows that the carbon dioxide and the aldehyde insertion proceeds through an inner-sphere mechanism. A variety of cis-butyrolactones can be synthesized with up to 7 : 1 diastereoselectivity and 77% yield.
Related Concept Videos
Preparation of Epoxides
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of...
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
Hydroboration-Oxidation of Alkenes
Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide


