Sodium Hydroxide → HCID 54228219, compound

Participants

Reaction Steps

10 mL of 0.5M solution of ethynylmagnesium chloride (5 mmoles) in tetrahydrofuran (purchased from Aldrich Chemical Co., Milwaukee, Wis.) was added to a 100 mL 3-neck reaction flask fitted with an addition funnel and an adapter connected to an apparatus similar to that described by Johnson and Schneider [Org. Synth., 30, 18 (1950)] so that the mixture in the flask could be protected from atmospheric moisture, et al. throughout the course of the reaction. After sweeping the system briefly with a stream of nitrogen gas and placing the flask in an ice-water bath (0° C.), a solution of 600 mg (2.91 mmoles) of 4-oxo-beta-ionone (prepared as described in Example V) in 4.0 mL of anhydrous tetrahydrofuran was added rapidly to the stirred Grignard reagent. The resulting mixture was stirred at 0° C. for an additional 60 minutes; after which it was diluted with 5 mL of hexane and the excess organometallic reagent was destroyed by slow, dropwise addition of 6 mL of saturated aqueous ammonium chloride. Isolation of the product as described in the procedure of Example III afforded 703 mg of a mixture of products, the major component of which was shown by proton NMR analysis to be the named keto alkynol (characterized by a singlet at δ 1.158--ascribed to the two methyls bonded to C-4). The other product was shown to be a diyne-diol (i.e., the bis Grignard adduct obtained by addition of ethynylmagnesium chloride to both carbonyl groups in 4-oxo-beta-ionone). The systematic name of the latter by-product is 1-ethynyl-3-(3-hydroxy-3-methylpent-1-en-4-ynyl)-2,4,4-trimethylcyclohex-2-en-1-ol; and its proton NMR spectrum is characterized by a singlet at δ 1.02--ascribed to the two methyls bonded to C-4. Upon treatment with powdered NaOH in a non-polar organic solvent at room temperature, the latter diyne-diol was converted to the desired product, the named keto alkynol. As described by the following procedure, this transformation can be conducted without the need for separation of the above mixture of products.

Provenance & Evidence