Ethyl (11bR)-4-Amino-2,6-bis(3,5-di-tert-butylphenyl)-4,5-dihydro-3H-cyclohepta[1,2-a:7,6-a']dinaphthalene-4-carboxylate

Experimental procedure:
To a stirred solution of 1 (10 mol%), N-chlorosuccinimide (1.5 eq.) in toluene is added α-alkyl-β-ketocarboxylic acid (1 eq.) and the reaction mixture is stirred under darkness. After completion, the resulting mixture is subjected directly silica gel column chromatography (hexane:dichloromethane) to give the corresponding α-chloroketone.

Typical Procedure (synthesis of 2-fluoro alcohol; Ar=Ph, R¹=CH₃):
To a solution of the chiral amine catalyst [E1267] (20 mg, 0.026 mmol, 10 mol%) in toluene (0.54 mL) is added 3,5-dinitrobenzoic acid (5.5 mg, 0.026 mmol, 10 mol%), 2-phenylpropionaldehyde (52 mg, 0.39 mmol, 1.5 eq.), and N-fluorobenzenesulfonimide (NFSI) (0.26 mmol, 82 mg, 1 eq.) at 0 °C. The reaction mixture is stirred at 0 °C for 48 h, then poured into CH₃OH/CH₂Cl₂ (1:4, 1.3 mL) at 0 °C. To this solution, NaBH₄ (1.6 mmol, 6 eq.) is added, and the mixture is stirred at room temperature for 1 h. The reaction is quenched with saturated aq.NH₄Cl, and the mixture is extracted with Et₂O. The organic layer is dried over Na₂SO₄, and concentrated. The residue is purified by silica gel chromatography (eluent: hexane/ethyl acetate = 3/1) to give (S)-2-fluoro-2-phenylpropan-1-ol (34.5 mg, 86% yield based on NFSI, 95% ee) as a white solid.