4-(6,7-Dimethyl-2-naphthyl)butanoic acid → 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene

HRID 1656871Notes

Reaction equation

[CH3:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][C:11]=1[CH3:12])[CH:8]=[C:7]([CH2:13][CH2:14][CH2:15][C:16]([OH:18])=O)[CH:6]=[CH:5]2>CS(O)(=O)=O>[CH3:12][C:11]1[CH:10]=[C:9]2[C:4](=[CH:3][C:2]=1[CH3:1])[CH:5]=[CH:6][C:7]1[CH2:13][CH2:14][CH2:15][C:16](=[O:18])[C:8]2=1

Participants

Conditions

Temperature: 90 °C

Procedure

4-(6,7-Dimethyl-2-naphthyl)butanoic acid (6.21 g, 0.026 mole) was added to 40 ml of CH3SO3H. The mixture was heated to 90° C. until all solid material disappeared (about 30 min.). The mixture was poured into ice and then extracted twice with ethylacetate. Combined ethylacetate solution was dried over anhydrous Na2SO4 and then concentrated. After flash chromatography on silica gel, 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene was obtained as a pale yellow solid material (4.96 g, 0.022 mole, 85% yield). mp 114.0°-115.0° C., 1H NMR (CDCl3)δ 2.12-2.20 (m,2H), 2.41 (s,3H), 2.47 (s,3H), 2.77 (t, J=6.4 Hz,2H), 3.09 (t, J=6.4 Hz,2H), 7.21 (d, J=8.3 Hz,1H), 7.54 (s,1H), 7.31 (d, J=8.3 Hz,1H), 9.20 (s,1 H), IR (KBr) cm-1 2930, 1669, 1590, 1510, Anal. Calcd. for C16H16O: C, 85.67; H, 7.19. Found: C, 86.00; H, 7.18.

Workup

custom(about 30 min.)
additionThe mixture was poured into ice
extractionextracted twice with ethylacetate
dry with materialCombined ethylacetate solution was dried over anhydrous Na2SO4
concentrationconcentrated

Sources & evidence

ORD record: ord-cea51c471876486b9f04f0913d966b94
Source dataset: uspto-grants-1993_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05256293

Reaction notes

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