p-Toluenesulfonic acid → HCID 15709511, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 6.80 g (51.1 mmole) of 4-(methoxymethyloxy)butanal, 5.10 g, (60 mmole) of piperidine and 0.5 g (2.9 mmole) of p-toluene-sulfonic acid in 200 mL of benzene was heated at reflux in a 500 mL flask that had been fitted with a Dean-Stark condenser. After 4 h the solution was cooled and concentrated under reduced pressure. The residue was dissolved in 50 mL of benzene and the solution was added dropwise to 500 mL flask containing a rapidly stirring solution of 5.40 g (50 mmole) of freshly sublimed benzoquinone in 50 mL of benzene. The solution grew hot during the addition and a red precipitate formed. After 4 h the solids were dissolved by the addition of 100 mL of dry THF. The solution was cooled to 0° C. in an ice bath and to the solution were added 11.2 g (100 mmole) of potassium t-butoxide and 5.4 mL (75 mmole) of allyl bromide. The mixture was stirred for 48 h, until alkylation was complete. The reaction mixture was partitioned between ether and water and the ether layer was washed with saturated NaHCO3 solution and saturated NaCl solution. The aqueous layers were washed sequentially with ether and the combined extracts were dried over magnesium sulfate and concentrated. The residue was purified by flash chromatography (12 cm column) using 20% ethyl acetate/hexane to afford 6.73 g (48%) of a pale orange oil. All attempts to distill this product and subsequent intermediates resulted in thermally induced Claisen rearrangement to the o-allyl phenols.

Provenance & Evidence