Enantioselective C H Amination with Ruthenium II Catalysts

Allylic C H insertion proceeds with complete selectivity for the C H bond, and competing aziridination is not observed. In contrast to the Rh2(S nap)4 catalyst system, a preference for trans olefins is observed under these conditions. Thus, trans olefin is converted to oxathiazinane 49 in good yield (60%) and selectivity (89% ee). Conversely, cis olefins are not good substrates for this catalyst. 

Disfavored steric clash between phenyl group and ligand 

A 10 ml round bottom flask was charged with sulfamate 34s (0.50 mmol), catalytic Rh2(S nap)4 (0.01 mmol, 0.02 equiv), powdered 3 A molecular sieves (265 mg), and 1.0 ml of CH2CI2. A single portion of Ph 1—0 (0.60 mmol, 1.2 equiv) was then added and the resulting pink suspension was stirred for 2 h. The reaction mixture was loaded directly onto silica gel and purified by chromatography (4 1 hexanes/FtOAc). The chiral oxathiazinane 34 was obtained as a white solid in 98% yield and 92% ee (Chiralcel OD H, 10% isopropanol/hexanes, l.Oml/min, 210nm, tr(minor) 

A 25 ml round bottom flask was charged with olefin 49s (82 mg, 0.046 mmol), bis (tert butylcarbonyloxy) iodobenzene (0.206 g, 0.506 mmol, 1.1 equiv), magnesium oxide (0.039 g, 1.07 mmol, 2.3 equiv), catalyst 43 (0.016 g, 0.023 mmol, 5 mol%), and silver triflate (6 mg, 0.023 mmol, 5 mol%). Benzene (3 ml) was added, and the resulting suspension was stirred at 22 °C for 24h. The reaction was then quenched by the addition of methanol (2.0 ml) and filtered over celite. The filter cake was washed with ethyl acetate (3 x 15 ml) and DCM (2 x 15 ml). The filtrate was con centrated under reduced pressure, and the crude oil purified by chromatography on silica gel (3 1 hexanes/EtOAc) afforded oxathiazinane 49 as a colorless oil (49 mg, 60%, 89% ee). GC (CHIRASIL DEX CB column) tr(major) =47.9 min, tr(minor) 

Starting from chiral alcohol 51, suggest synthesis of p amino add 52. 

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