1-(Tert-butoxy)-4-ethenylbenzene → (1R,2R)-2-(4-tert-Butoxy-phenyl)-cyclopropanecarboxylic acid ethyl ester

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Reaction Steps

The title compound is prepared from 4-tert-butoxystyrene (4.3 g, 24.4 mmol) in a manner analogous to that described for Intermediate 4, step 1, using (S,S)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline) (72 mg, 0.24 mmol) as the ligand (yield 6.4 g). LC (GC METHOD 1): tR=11.47 min; Mass spectrum (EI+): m/z=262 [M]+, e.e. 94% by chiral HPLC. (Column: Daicel Chiralcel OJ-H, 4.6×250 mm, 5 μm Mobile phase: hexane:ethanol 95:5, 1 mL/min, 25° C.) tR=8.94 (9.93) min

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