methyl 7-[(3S)-3-hydroxy-5-oxocyclopenten-1-yl]heptanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: When an equivalent quantity of methyl 7-(3(RS)-hydroxy-5-oxocyclopent-1-en--yl)heptanoate is substituted for the methyl 7-(3(S)-hydroxy-5-oxocyclopent-1-en-1-yl)-heptanoate and the procedure detailed in Part A substantially repeated, there is obtained methyl 7-(3(RS)-tetrahydropyran-2-yloxy-5-oxocyclopent-1-en-1-yl)heptanoate.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Substitution of an equivalent quantity of methyl 7-(3(R)-hydroxy-5-oxocyclopent-1-en-1-yl)heptanoate for the methyl 7-(3(S)-hydroxy-5-oxocyclopent-1-en-1-yl)heptanoate and substantial repetition of the procedure detailed above affords methyl 7-(3(R)-tetrahydropyran-2-yloxy-5-oxocyclopent-1-en-1-yl)heptanoate.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1.74 parts of methyl 7-(3(S)-hydroxy-5-oxocyclopent-1-en-1-yl)heptanoate in 12 parts by volume of dry benzene is added 0.005 part of p-toluenesulfonic acid and 1.74 parts of dihydropyran. The reaction mixture is stirred for 5 minutes under a nitrogen atmosphere and then allowed to stand at room temperature for a further 2 hours. The resulting solution is diluted with ethyl acetate, washed with water, dried over anhydrous sodium sulfate, and stripped of solvent under reduced pressure to afford methyl 7-(3(S)-tetrahydropyran-2-yloxy-5-oxocyclopent-1-en-1-yl)-heptanoate. to stand at room temperature for a further 2 hours washed with water dried over anhydrous sodium sulfate