Use of Planar Chiral Ferrocenyl­phosphine‐Gold(I) Complexes in the Asymmetric Cycloisomerization of 3‐Hydroxylated 1,5‐Enynes

Abstract

Chiral monodentate phosphines based on ortho‐disubstituted ferrocene units have been prepared and used for the synthesis of gold(I) complexes. These complexes are highly active catalysts for the cycloisomerization of 3‐hydroxy‐1,5‐enynes into bicyclo[3.1.0]hexanones. Their high catalytic activity is ascribed to their structural analogy to the biaryl‐based Buchwald phosphines. This paper discloses the first enantioselective variant of these reactions based on gold catalysis (ee's up to 80 %).

Why is Ferrocene so Exceptional?

“…The extremely rich reactivity of ferrocene has allowed the synthesis of very useful and currently widely utilized ligands, especially a large variety of ferrocenylphosphines that are accessible either from lithioferrocene and 1,1′‐dilithioferrocene (Scheme ) or through direct Friedel–Crafts reactions with ferrocene in the presence of aluminum chloride . The achiral diphosphine 1,1′‐bis(diphenylphosphino)ferrocene (dppf) is especially widely used in catalysis; in particular, its palladium complex [Pd II Cl 2 (dppf)] is used for palladium‐coupling reactions with industrial applications in pharmaceuticals and agrochemistry.…”

Ferrocenyl Gold Complexes as Efficient Catalysts

“…In 2016, Marinetti, Voituriez and co-workers reported a series of MOPF ligands synthesized starting from (S,R p )-1-iodido-2-p-tolylsulfinylferrocene (60, Scheme 19). [43] Hence, through a Suzuki coupling of (S,R p )-60 with three different boronic These complexes were then evaluated in the cycloisomerization of 3-hydroxy-1,5-enynes 64 into bicyclo[3.1.0]hexan-3ones 65. Best results were achieved by catalyst 63 c in dichloromethane and AgOTf as the activator salt.…”

Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis

“…In 2016, Voituriez and Marinetti [28] demonstrated asymmetric cycloisomerization of 3‐hydroxylated 1,5‐enynes catalyzed by planar chiral ferrocenylphosphine‐gold(I) complexes. As aryl‐monophosphino ferrocenes (MOPF) were previously adopted for Pd‐MOPF and Cu–MOPF catalysts, [29] the use of Au‐MOPF complexes for asymmetric catalysis remains rare [30] .…”