Iodine → Lithium diisopropylamide

Participants

Reaction Steps

LDA was prepared by addition of n-BuLi (1.56 mol/l hexane solution) 1.08 ml to a solution of diisopropylamine 255 μl in dry tetrahydrofuran 3 ml at −70° C. Then, a solution of compound (20-1) 500 mg in dry tetrahydrofuran 2 ml was added at that temperature to the mixture, which was stirred for 2 h. Then, a solution of iodine 426 mg in dry tetrahydrofuran 2 ml was added and the mixture was stirred for 2 h. Ice was added to the reaction mixtures, which was extracted with chloroform. The extracts were washed with brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue obtained was chromatographed on aluminum oxide in ethyl acetate:hexane (1:5) to give the titled compound as colorless crystals 514 mg. Yield 76%. This was recrystallized from from acetone-isopropyl ether to give colorless crystals, m.p. 136-137° C.

Provenance & Evidence