(RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzaldehyde → 2-cyclopropyl-7,8-dimethoxy-2H-chromene-5-carbaldehyde

HRID 964970Notes

Reaction equation

[CH:1]1([CH:4]([O:7][C:8]2[CH:9]=[C:10]([CH:13]=[C:14]([O:18][CH3:19])[C:15]=2[O:16][CH3:17])[CH:11]=[O:12])[C:5]#[CH:6])[CH2:3][CH2:2]1>C(N(CC)C1C=CC=CC=1)C>[CH:1]1([CH:4]2[CH:5]=[CH:6][C:9]3=[C:10]([CH:11]=[O:12])[CH:13]=[C:14]([O:18][CH3:19])[C:15]([O:16][CH3:17])=[C:8]3[O:7]2)[CH2:3][CH2:2]1

Participants

Conditions

Temperature: 200 °C

Procedure

2.4 g of (RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzaldehyde were dissolved in 20 ml of N,N-diethyl-aniline, heated to 200° C. under argon and stirred at 200° C. for a further 1 hr. The solvent was distilled off at 90° C./1 mbar and the residue was extracted: 2×100 ml of diethyl ether, 2×100 ml of 1N HCl, 2×100 ml of saturated NaCl. The crude product was purified by two-fold silica gel chromatography with dichloromethane and, respectively, ethyl acetate/hexane 5:1. (RS)-2-Cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-carbaldehyde was obtained as a brown oil (HPLC 96%).

Workup

distillationThe solvent was distilled off at 90° C./1 mbar
extractionthe residue was extracted
customThe crude product was purified by two-fold silica gel chromatography with dichloromethane

Sources & evidence

ORD record: ord-b8cc833b29334574ad08fd6bbbabde0b
Source dataset: uspto-grants-1998_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05773446

Reaction notes

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