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A NOVEL PROCESS FOR THE THREE STEP PROTECTING GROUP FREE SYNTHESIS OF(+)-CARDIOBUTANOLIDE OF FORMULA (1)
 

This invention relates to a process for preparing (+)-cardiobutanolide of formula (1) comprising the following steps:

  1. Treating D-glucono-δ-lactone formula (2)

    with hydrogen bromide in acetic acid followed by Zn powder in 50% acetic acid in water at ambient temperature to obtain (3R,4R)-3,4-Dihydroxy-5-hexenoic acid-γ-lactone of formula (3).

  2. Olefin cross metathesis reaction between hydroxyl lactone (3) obtained in step (a) and commercially available (S)-phenyl vinyl carbinol (4) using Grubbs-Hoveyda second generation catalyst in anhydrous CH2Cl2 under conditions effective to yield a olefinic compound of formula (5)
  3. Dihydroxylation using K2OsO4.2H2O and N-methylmorpholine-N-oxide on olefin compound (5) obtained in step (b) in acetone and water under conditions effective to obtain (+)-cardiobutanolide (1) and its diastereomer of formula (6) in 4:1 ratio

Indian patent application no. 1780/MUM/2012

Inventors: Rodney A. Fernandes, K.Pullaiah