p-Toluenesulfonic acid → HCID 15709511, compound

Temperature

0 °C

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.

1. temperatureat reflux in a 500 mL flask that
2. customhad been fitted with a Dean-Stark condenser
3. temperatureAfter 4 h the solution was cooled
4. concentrationconcentrated under reduced pressure
5. dissolutionThe residue was dissolved in 50 mL of benzene
6. additionthe solution was added dropwise to 500 mL flask
7. additioncontaining a rapidly stirring solution of 5.40 g (50 mmole) of freshly sublimed benzoquinone in 50 mL of benzene
8. additionThe solution grew hot during the addition
9. customa red precipitate formed
10. customThe reaction mixture was partitioned between ether and water
11. washthe ether layer was washed with saturated NaHCO3 solution and saturated NaCl solution
12. washThe aqueous layers were washed sequentially with ether
13. dry with materialthe combined extracts were dried over magnesium sulfate
14. concentrationconcentrated
15. customThe residue was purified by flash chromatography (12 cm column)

ORD record

ord-04b040b8d37640fda9934e1ee430639b

Source dataset

uspto-grants-1990_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04978679