2-Bromo-3-methyl-2-cyclopenten-1-ol → 2-Ethyl-3-methyl-cyclopent-2-enol

Participants

Reaction Steps

The alcohol (Intermediate V2, 16 mmol) in THF (30 mL) at 0 EC was treated with ethyl magnesium bromide (40 mmol). The catalyst, 1,3-bis(diphenylphosphino)propane nickel (II) chloride (0.75 mmol) (NiCl2dppp) was added in one portion and the mixture was heated to reflux for 3 hours following the procedure of Organ et al. J. Org. Chem. 1997, 62, 1523, incorporated herein by reference.) The reaction mixture was cooled to rt and quenched with sat. NH4Cl solution. The mixture was filtered and partitioned between brine and diethyl ether. The organic layer was removed and dried over Na2SO4, filtered and concentrated under vacuum. The oil was purified by chromatography on SiO2 with 20% EtOAc:Hx to yield 2-ethyl-3-methyl-cyclopent-2-enol (Intermediate V3). Use of the alcohol (Intermediate V3) in the applicable steps of Method A and Method P produced 4-(2-ethyl-3-methyl-cyclopent-2-enylmethyl)-1,3-dihydro-imidazol-2-one (Compound 64). 1H NMR (300 MHz, CD3OD-d4): δ 6.03 (s, 1H), 2.88 (brs, 1H), 2.65-2.59 (m, 1H), 2.27-1.83 (series of m, 6H), 1.62 (s, 3H), 1.54-1.45 (m, 1H), 0.97 (t, J=6 Hz, 3H).

Provenance & Evidence