Menthol → Ethyl 2-phenylcyclopropane-1-carboxylate

HRID 1611559Notes

Reaction equation

HRID 1611559 reaction equation
C=CC1C=CC=CC=1.[N+](=CC(OCC)=O)=[N-].[C:17]1([C@@H:23]2[CH2:25][C@H:24]2[C:26]([O:28][CH2:29][CH3:30])=[O:27])[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1.C1(C)CCC(C(C)C)C(O)C1.C1([C@@H]2C[C@H]2C([O-])=O)C=CC=CC=1>ClCCl>[C:17]1([CH:23]2[CH2:25][CH:24]2[C:26]([O:28][CH2:29][CH3:30])=[O:27])[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1

Participants

7

Reactant 5

HCID 1254MentholHCID 7501StyreneHCID 12192Ethyl diazoacetateHCID 252496Ethyl trans-2-phenylcyclopropanecarboxylateHCID 6931403trans-2-Phenylcyclopropanecarboxylate

Product 1

HCID 316914Ethyl 2-phenylcyclopropane-1-carboxylate

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent3×

Procedure

To a mixture of styrene (2.15g, 20.7 mmol) and Rh2(4S-BNOX)4 (0.0113 g, 0.0131 mmol) in 5.0 mL of anhydrous dichloromethane was added, by syringe at room temperature, ethyl diazoacetate (0298 g, 2.62 mmol) in 3.0 mL of dichloromethane under nitrogen and at an addition rate of 0.8 mL/h (syringe pump). After addition was complete, the dichloromethane solution was passed through a plug of neutral alumina to separate the catalyst, and solvent and excess styrene were removed under reduced pressure Gas chromatographic separation of the trans-isomer produced a material whose specific rotation was −6.4° which corresponded to an enantiomeric excess of the ethyl (1R,2R)-2-phenylcyclopropanecarboxylate. Conversion of the ethyl esters to the 1-menthyl esters by base hydrolysis, acid chloride formation, and esterification with (−)-menthol provided a gas chromatographically separable mixture that showed 25% enantiomeric excess for the (1R,2R)-enantiomer of the trans-2-phenylcyclopropanecarboxylate.

Workup

  1. additionwas added, by syringe at room temperature
  2. additionAfter addition
  3. customto separate the catalyst, and solvent and excess styrene
  4. customwere removed under reduced pressure Gas chromatographic separation of the trans-isomer
  5. customproduced a material whose specific rotation
  6. customwas −6.4°
  7. customprovided a gas chromatographically separable mixture that

Sources & evidence

ORD record
ord-8202430d3f54493e994621d19819d012
Source dataset
uspto-grants-2006_01
Patent number
USRE038947E1

Reaction notes

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