Palladium‐Catalyzed Decarboxylative Cycloaddition of Vinylethylene Carbonates with Formaldehyde: Enantioselective Construction of Tertiary Vinylglycols

Abstract

An efficient method for the enantioselective construction of tertiary vinylglycols through a palladium-catalyzed asymmetric decarboxylative cycloaddition of vinylethylene carbonates with formaldehyde was developed. By using a palladium complex generated in situ from [Pd 2 -(dba) 3 ]·CHCl 3 and a phosphoramidite ligand as a catalyst under mild reaction conditions, the process allows conversion of racemic 4-substituted 4-vinyl-1,3-dioxolan-2-ones into the corresponding 1,3-dioxolanes, as methylene acetal protected tertiary vinylglycols, in high yields with good to excellent enantioselectivities.

Advances in Stereoconvergent Catalysis from 2005 to 2015: Transition-Metal-Mediated Stereoablative Reactions, Dynamic Kinetic Resolutions, and Dynamic Kinetic Asymmetric Transformations

“…225 Their approach utilizes racemic vinyl-substituted ethylene carbonates as substrates that undergo CO 2 extrusion upon exposure to catalytic Pd 2 (dba) 3 ·CHCl 3 and ( S , S , S )-phosphoramidite 174 (Figure 20), leading to a rapidly interconverting dynamic system comprising of diastereomeric π-allylpalladium intermediates. Formaldehyde then reversibly captures the Pd-alkoxide intermediate, generating a new pair of diastereomeric Pd-allyl complexes, which is much slower to equilibrate.…”

A Mechanistic Analysis of the Palladium‐Catalyzed Formation of Branched Allylic Amines Reveals the Origin of the Regio‐ and Enantioselectivity through a Unique Inner‐Sphere Pathway

“…[6] Recently,P d-catalyzed efficient decarboxylative transformations of vinylethylene carbonates (VCCs) with various electrophiles and (pro)nucleophiles have been reported. [7][8][9][10] In this context, Kleij, Maseras and co-workers developed aP d-catalyzed allylic substitution of VCCs 1 with aryl-and alkyl-amines (Scheme 1c). [8] Notably,w ith the diphosphine ligand L1,c omplete linear regioselectivity and high (Z)stereoselectivity was observed, thus providing ag eneral method for the stereoselective construction of tri-and tetrasubstituted allylic amines (Z)-2.Adetailed reaction mechanism was also provided by DFT calculations,a nd the computational results showed that the reaction follows ag enerally accepted outer-sphere pathway in line with the experimental results.A talater stage,K leij and co-workers found that the regioselectivity of this reaction can be switched towards the branched product through ligand control.…”

Palladium‐Catalyzed Decarboxylative Asymmetric Allylic Alkylation: Development, Mechanistic Understanding and Recent Advances

“…Formaldehyde could also be used efficiently in the decarboxylative [3+2] cycloaddition with VECs 215 to form 1,3‐dioxolanes 243 with excellent enantioselectivities using the chiral phosphoramidite ligand 239 . The methylene acetal‐protected tertiary vinylglycol products 243 are useful chiral precursors for natural products as they can be readily deprotected, forming the corresponding tertiary vinylglycols without erosion of enantioselectivity (Scheme A).…”