To a stirring solution of 1-(4-Bromo-benzyl)-pyrrolidine (Lednicer, Daniel; Lyster, Stanley C.; Duncan, Gordon W. Mammalian antifertility agents. IV. Basic 3,4-dihydronaphthalenes and 1,2,3,4-tetrahydro-1-naphthols. Journal of Medicinal Chemistry (1967), 10(1), 78–84, J. Org. Chem; EN; 46; 17; 1981; 3571–3574) (0.71 g, 2.96 mmol) in THF (13 mL) at −78° C. (isopropanol/CO2) was added a solution of n-butyl lithium (1.6 mL, 3.93 mmol, 2.5 M hexanes). After 15 minutes a pre-cooled (−78 □C) solution of 3-pyrrolidin-1-ylmethyl-cyclobutanone (Intermediate 6, General procedure B Step C) (0.2 g, 1.3 mmol, in 3 mL THF) was added down the side of the flask. After TLC analysis indicated complete consumption of starting material the reaction was quenched cold by the addition of a saturated solution of NH4Cl. The reaction was then warmed to room temperature and diluted with CH2Cl2. The layers were separated and the aqueous layer was extracted with CH2Cl2. The combined organic layers were discarded. The aqueous layer was then extracted with 3:1 (CHCl3:isopropyl alcohol) and the combined organic layers were dried over magnesium sulfate, filtered through a fritted funnel, and concentrated under reduced pressure. The material was purified by trituration using ether:hexanes to yield the title compound (0.24 mg, 58% yield) as a colorless solid and a mixture of cis:trans isomers.
