Toluene → 2-Methyl-4-(propan-2-yl)cyclohex-3-en-1-one

HRID 2163626Notes

Reaction equation

HRID 2163626 reaction equation
[C:1]1(C)C=CC=CC=1.[O:8]1[C:14]2(C)[CH:9]1[CH:10]1[C:16]([CH3:18])([CH3:17])[CH:11]1[CH2:12][CH2:13]2>CCOCC.[Zn+2].[Br-].[Br-]>[CH3:1][CH:9]1[CH:10]=[C:11]([CH:16]([CH3:17])[CH3:18])[CH2:12][CH2:13][C:14]1=[O:8]

Participants

5

Reactant 2

HCID 1140Toluene2×HCID 576910HCID 576910, compound

Product 1

HCID 227507372-Methyl-4-(propan-2-yl)cyclohex-3-en-1-one

Reagents, catalysts & solvents 2

HCID 10421208Zinc bromideCatalystHCID 3283Diethyl EtherSolvent

Procedure

Approximately 20 mg of ZnBr2 (Fisher Certified-not fused) was added to 3 mL of toluene which had been distilled and stored over molecular sieves. The mixture was brought to reflux with vigorous stirring (to disperse the solid zinc bromide) in an apparatus which had been well flushed with nitrogen and equipped with a drying tube. Three quarters of a mixture of 2,3-epoxycarane (150 mg, 0.98 mmol) and 3 mL of toluene was added immediately. After 10 min the remaining one quarter was added over a 10 min period. Forty minutes after initial oxide addition the reaction mixture was cooled, taken up in 30 mL of ether, washed successively with water (2 × 10 mL), saturated NaHCO3 (1 × 10 mL), saturated NaCl (1 × 10 mL) and dried over anhydrous Na2SO4. Partial removal of solvent under reduced pressure afforded an oily residue from which 2-methyl-4-isopropylcyclohex-3-en-1-one (MICO) was isolated by preparative VPC. IR (CCl4) 2975, 1720, 1360, 1200, 1180(d), 970 and 930 reciprocal centimeters; UV (95% EtOH) lambda (max) 290 nm (extinction coefficient = 90.9); NMR (DCCl3) PPM 1.04 (d, 6H, J = 7 Hz, CH3 --C--CH3), 1.14 (d, 3H, J = 7 Hz, CH3 --C--), 2.3 (quintet, 1H, J = 7 Hz), 2.46 (n, M, 4H), 2.88 (br, Q with additional splitting H--C--C=O), 5.37 (n, M, 1H, H--C=C); MS m/e (rel. intensity) 153(4), 152(42), 135(5), 100(65), 109(10), 96(11), 95(100), 81(30), 68(10), 67(25), 55(11). Anal. calcd. for C10H16O: C, 78.89; H, 10.59. Found: C, 79.08; H, 10.41. An IR of the major product of the reaction showed a peak at 1720 reciprocal centimeters, attributed to the presence of a nonconjugated carbonyl. The product MICO exhibited a cool, refreshing menthol fragrance with a slight raspberry note which finds utility for the compound in odorant compositions.

Workup

  1. distillationhad been distilled
  2. temperatureto reflux
  3. additionto disperse the solid zinc bromide) in an apparatus which
  4. customhad been well flushed with nitrogen
  5. customequipped with a drying tube
  6. additionwas added immediately
  7. additionAfter 10 min the remaining one quarter was added over a 10 min period
  8. temperaturewas cooled
  9. washwashed successively with water (2 × 10 mL), saturated NaHCO3 (1 × 10 mL), saturated NaCl (1 × 10 mL)
  10. dry with materialdried over anhydrous Na2SO4
  11. customPartial removal of solvent under reduced pressure

Sources & evidence

ORD record
ord-02c1457d48ad4676a87b2ecb74664d47
Source dataset
uspto-grants-1979_01
Patent number
US04136119

Reaction notes

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