Binaphthalene‐Derived Iminium Salt Catalysts for Highly Enantioselective Asymmetric Epoxidation

Abstract

Enantiomerically enriched epoxides are useful intermediates that have found many applications in asymmetric synthesis, and development of efficient catalysts for asymmetric epoxidation has received considerable attention. In this manuscript we describe the design, preparation, and use of new highly selective iminium salt organocatalysts for asymmetric

Green Organocatalytic Oxidative Methods using Activated Ketones

“…[32] Along the lines of oxaziridines, Bulman Page and co-workers have spent most of their research in the epoxidation of alkenes by using iminium salts such as 13 and 14 ( Figure 1). [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] More recently,i n2 013, Bulman Page managed to extend the use of catalyst 15 in heterogeneousc atalysis, while showing the first resultso fk inetic resolution in the epoxidation reaction by employing iminium salt catalysis,b yw hich enantiomeric excess values of up to 99 %f or the epoxidation of racemic cischromenes could be achieved (Scheme 11). Furthermore, a new familyo fc arbohydrate-based dihydroisoquinolinium salts 14 and 16 has been reported,a nd most recently,B ulman Page and co-workersh ave developed the first examples of the asymmetrice poxidation of dihydroquinoline substrates with iminium salt catalysts (Scheme 12).…”

An Unexpected Oxidative C-O Bond Formation: 11,17a-Dihydrobenzo[4,5]oxazolo[3,2-A]dinaphtho[2,1- C:1',2'-E]azepine

“…As a chiral precursor, we prepared dibromide (R)-1 in three steps from (R)-BINOL according to Bulman Page et al [16] and Rosini et al [17] (Scheme 1). We then attempted to synthesize aminophenol 2 under standard conditions but observed formation of dihydrooxazole 3, obviously the oxidation product of 2.…”

Enantioselective catalytic lithiation using a chiral binaphthyl derivative as electron carrier

“…35,36 (S)-2,2'-Bis(trifluoromethanesulfonyloxy)-1,1'-binaphthalene (10, 1 g, 1.8 mmol) and bis(triphenylphosphine)-nickel(II) chloride (84 mg, 0.13 mmol) were placed in a 50 mL round-bottom flask under argon, and dry Et 2 O (12 mL) was subsequently added. The reaction mixture was cooled to 0 ºC and MeMgBr (sol.…”