Water → 3,3a,4,5,6,6a-hexahydro-2H-pentalen-1-one

HRID 462773Notes

Reaction equation

HRID 462773 reaction equation
COC(CCC/C=[C:9]1/[C:10](=[O:17])[CH:11]2[CH:15]([CH2:16]/1)[CH2:14][CH2:13][CH2:12]2)=O.[OH-].[Li+].O>CO>[CH:11]12[CH2:12][CH2:13][CH2:14][CH:15]1[CH2:16][CH2:9][C:10]2=[O:17]

Participants

5

Reactant 3

HCID 962WaterHCID 3939Lithium HydroxideHCID 867400973-[(E)-4-methoxycarbonylbutylidene]bicyclo[3,3,0]octan-2-one

Product 1

HCID 1406313,3a,4,5,6,6a-hexahydro-2H-pentalen-1-oneYield 95.1%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

A stirred solution of 6-[(E)-3-cyclohexyl-(mixture of 3α and 3β)-hydroxyprop-1-enyl]-3-[(E)-4-methoxycarbonylbutylidene]bicyclo[3,3,0]octan-2-one (20 mg), prepared as described in Example 8 and predominantly in the 6β-configuration, otherwise known as (±)-methyl(5E,13E)-(9S),[mixture of (15R) and (15S)]-6a-oxo-6,9-methano-15-cyclohexyl-15-hydroxy-16,17,18,19,20-pentanorprosta-5,13-dienoate, in methanol (3.2 ml) was treated with lithium hydroxide (33.8 mg) and water (1.1 ml) at 20° C. and stirred for 2 hours. The mixture was then concentrated in vacuo. The resulting residue was diluted with water (5 ml) and then acidified to pH 3 by treatment with dilute hydrochloric acid (2N). The aqueous layer was then extracted with ethyl acetate (5×5 ml). The combined organic extracts were dried over anhydrous sodium sulphate and concentrated in vacuo. The resulting residue was subjected to chromatography on a silica gel column, using a mixture of ethyl acetate, hexane and formic acid (50:50:1 by volume) as eluant, to give 3-[(E)-4-carboxybutylidene]-6-[(E)-3-cyclohexyl-(mixture of 3α and 3β)-hydroxyprop-1-enyl]bicyclo[3,3,0]octan-2-one (10 mg), predominantly in the 6β-configuration, otherwise known as (±)-(5E,13E)-(9S),[mixture of (15R) and (15S)]-6a-oxo-6,9-methano-15-cyclohexyl-15-hydroxy-16,17,18,19,20-pentanorprosta-5,13-dienoic acid [NMR in deuterochloroform: multiplets at 6.5, 5.5, 4.2-3.5, 3.0-0.7 p.p.m⟧

Workup

  1. concentrationThe mixture was then concentrated in vacuo
  2. additionThe resulting residue was diluted with water (5 ml)
  3. extractionThe aqueous layer was then extracted with ethyl acetate (5×5 ml)
  4. dry with materialThe combined organic extracts were dried over anhydrous sodium sulphate
  5. concentrationconcentrated in vacuo
  6. additiona mixture of ethyl acetate, hexane and formic acid (50:50:1 by volume) as eluant

Sources & evidence

ORD record
ord-6531be4909ea48b68e1c40289d055a64
Source dataset
uspto-grants-1985_05
Patent number
US04517202

Reaction notes

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