Palladium‐Catalyzed Allylation of Vinylethylene Carbonates with β‐Ketophosphonates: Stereoselective Synthesis of (Z)‐Homoallylic Phosphonates

Abstract

A first simple palladium catalyzed allylation of vinylethylene carbonates with β‐ketophosphonates has been developed. This method provides access to (Z)‐tri‐ and tetrasubstituted homoallylic phosphonates with exclusive regioselectivity, chemoselectivity and (Z)‐stereoselectivity. The reaction tolerates a wide substrate scope of vinylethylene carbonates and β‐ketophosphonates with electron‐donating and electron‐withdrawing groups and works well on the gram scale.

Stereoselective Synthesis of (Z)‐Dihomoallylic Phosphonates with Quaternary Carbon Center by Palladium‐Catalyzed Bisallylation of Vinylethyene Carbonates with β‐Ketophosphonates

“…The success of these transformations lies in the in situ formation of a highly reactive zwitterionic π ‐allylic palladium intermediate, which can readily undergo nucleophilic substitution to generate allylic manifolds. Most recently, we discovered a palladium‐catalyzed allylation of vinylethylene carbonates with β ‐ketophosphonates to produce monohommoallylic phosphonates [18] . We speculated if further screening conditions, the dihomoallylic phosphonates bearing a quaternary carbon centers could be obtained in this transformation (scheme 1).…”

“…Most recently, we discovered a palladium-catalyzed allylation of vinylethylene carbonates with β-ketophosphonates to produce monohommoallylic phosphonates. [18] We speculated if further screening conditions, the dihomoallylic phosphonates bearing a quaternary carbon centers could be obtained in this transformation (scheme 1). Given the formidable challenge of diallylation, we believed this investigation should be of great interest.…”

Cross-coupling of aldehydes and α-bromophosphonates to modularly access α-substituted-β-ketophosphonates under dual nickel/photoredox catalysis

“…However, comparatively, there are relatively very few methods to conveniently and directly obtain α-substituted-β-ketophosphonates (Scheme 1). Generally, they have to be prepared from β-ketophosphonates via enolization with strong bases and subsequent nucleophilic substitution with active alkyl halides 10 or via α-functionalization with a transition metal catalyst 11 (Scheme 1a). Despite several additional studies with sporadic examples of α-substituted-β-ketophosphonate formation, 12 apparently, a modular and facile method to deliver this type of product is still highly demanded.…”