Terrein, an optically active prostaglandin synthon of fungal origin. II. Chemical conversion to 4(R)-acetoxy-2-cyclopentenone.
✍ Scribed by L.A. Mitscher; G.W. Clark III; P.B. Hudson
- Book ID
- 104245849
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- French
- Weight
- 166 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
Synthetic approaches to the prostaglandins are still of high interest because natural sources are unable to supply the projected needs. Recent efforts in several laboratories have been devoted to chiral processes in an effort to avoid wasteful resolution steps. The recent establishment of 4(R)-acetoxy-2cyclopentenone, 1, by Kurozumi, et al. --(Table I) as a prostaglandin synthon by use of a combined chemical-microbiological process is a case in point.' Stork, et al. had previously published a prostaglandin synthesis based upon a similar--ly substituted but racemic intermediate. 3 We wish to report a convenient preparation of the optically active Kurozumi synthon of Aspergillus fischerii 4-8 which has the correct prostaglandin synthesis. Terrein, 2_, was converted selectively to its crystalline 5-acetyl deriva-from terrein, 2, a metabolite absolute configuration for tive, 3, in 75% yield, by warming at 650 for 48 hr. in a THF, acetic anhydride (1 equivalent), sodium acetate (1.5 equivalents) slurry [mp 96.5-970, xz',l3 278 nm (~=28,600), m/e 196 (M+)l. Reduction of 2, in acetone with chromous chloride solution 10,ll afforded 4 as a clear yellow oil in 99% yield [X2:13 270 nm (~=17,600); m/e 138 (M+); pmrCDC13 2.36(dd, J = 2,20 Hz, lH, H..=C-C=O), 2.86(dd, J = 5,20 Hz, lH, HbC-C=O),and 5.26(dd, J = 5,2 Hz, H,C-CH2-C=O)].