3, 3-dimethyl-7-methylenecycloocta-1, 5-dione, a versatile building block for the preparation of substituted cyclooctadienones and δ-valerolactones

JA Bajgrowicz, M Petrzilka

Index: Bajgrowicz, Jerzy A.; Petrzilka, Martin Tetrahedron, 1994 , vol. 50, # 25 p. 7461 - 7472

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Abstract

De Mayo reaction of dimedone with allene results in the formation of 3, 3-dimethyl-7- methylenecycloocta-1, 5-dione 6 together with the corresponding head-to-tail adduct 5 which spontaneously dimerizes to the hetero Diels-Alder adduct 7. Reduction of 6 together with sodium borohydride or Grignard reagents affords the transannular hemiketals 9 which can easily be isomerized (DBU) to their conjugated analogues 10. Depending on the ...