3,4-dihydro-2H-pyran → HCID 22405689, compound

A modification of a procedure reported by Grandberg (Chem. Abstr. 1973, 79,918895) was used. Thus, to a suspension of 4-bromophenylhydrazine hydrochloride (56.0 g, 0.25 mol) in 200 mL of 2-methoxyethanol was added 3,4-dihydro-2H-pyran (25.5 mL, 0.28 mol) over ca. 5 min and the resulting mixture was heated to reflux under Ar for 3.5 h. The cooled reaction mixture was evaporated and the residual oil was poured into 500 mL of cold water. The aqueous mixture was extracted with ether (2×250 mL) and the ethereal extract was washed with H2O (250 mL), 1N HCl (2×250 mL) and brine (250 mL). The organic phase was then dried (Na2SO4) and evaporated to give a dark orange-brown oil. This oil was purified on a 10×15 cm SiO2 pad (elution with CH2Cl2 then CH2Cl2 -ethyl acetate, 1:1) to give the title compound (43.7 g, 69%) as a viscous orange-brown oil: IR (neat) 3570, 3430, 3300 (br), 1460 cm-1 ; 1H NMR (CDCl3, 200 MHz) δ0.11 (br s, 1H), 7.73 (d, J=1.8 Hz, 1H), 7.30-7.18 (m, 2H), 6.97 (s, 1H), 3.72 (t, J=6.4 Hz, 2H), 2.80 (t, J=7.5 Hz, 2H), 2.03-1.89 (m, 2H), 1.68 (br s, 1H).

1. temperaturethe resulting mixture was heated
2. temperatureto reflux under Ar for 3.5 h
3. customThe cooled reaction mixture
4. customwas evaporated
5. additionthe residual oil was poured into 500 mL of cold water
6. extractionThe aqueous mixture was extracted with ether (2×250 mL)
7. extractionthe ethereal extract
8. washwas washed with H2O (250 mL), 1N HCl (2×250 mL) and brine (250 mL)
9. dry with materialThe organic phase was then dried (Na2SO4)
10. customevaporated
11. customto give a dark orange-brown oil
12. customThis oil was purified on a 10×15 cm SiO2 pad (
13. washelution with CH2Cl2

ORD record

ord-5f23215a82a44937a78fc8ece0be5da6

Source dataset

uspto-grants-1995_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05382592