3-Penten-2-one, 5-(2,2,3-trimethyl-3-cyclopenten-1-yl)- → 4-Penten-2-one, 5-(2,2,3-trimethyl-3-cyclopenten-1-yl)-

Participants

Reaction Steps

The ketone, 5-(2,2,3-trimethylcyclopent-3-en-1-yl)pent-3-en-2-one, which had been prepared by using the procedure of U.S. Pat. No. 4,052,341, Example II-2, was reacted essentially following the procedure described in Example I for isomerizing the α,β double bond to the β,γ position. In this case the ketone (28.8 g, 0.15 mole) was reacted with potassium t-butoxide (25.8 g, 0.23 mole) in 1,2-dimethoxyethane (DME) (125 ml). The reaction was quenched by addition of aqueous 20% acetic acid (115 ml), extracted as in Example I and the oil distilled at reduced pressure to yield 19.0 g (66% yield) of 5-(2,2,3-trimethylcyclopent-3-en-1-yl)pent-4-en-2-one as a mixture of Z- (21%) and E- (69%) isomers: bp 80°-100° C. (0.5 mm); mol. wt. 192 (MS); IR 3040 cm-1 (olefin), 1720 (carbonyl), 800 (trisubstituted olefin).

Provenance & Evidence