Asymmetric total synthesis from cyclopentene-1,2-diones: Characterisation of a diastereomerically pure michael adduct
✍ Scribed by Richard T. Brown; Mark J. Ford
- Book ID
- 104222175
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- French
- Weight
- 237 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
A key cyclopentenolone intermediate in the asymmetric synthesis of alkaloids and seco-iridoids has been prepared from reaction of a chiral5,7-dioxoperhydro-1 ,Coxazepine with a cyclopentene-1,2-dione dimer; the absolute configuration at the induced chiral centres has been assigned from n. 0. e. experiments. The iridoid glucoside secologanin 1 is the key biological precursor for virtually all monoterpenoid indole and related alkaloids. In its transformations in vivo and in vitro it behaves as the trisaldehyde 2 for which we have devised a synthetic equivalent in the lactol 3. The latter was prepared' in racemic form from the novel dimer 6 via the cyclopentenolone 4, and converted into representative. alkaloids: (f)-hirsutine, protoemetine and related base&s.
Racemic dihydrosecologanin aglucone, E-secologanin aglucone and elenolide have also been obtained from 4 using a novel decarbomethoxylation procedured.