The dye-sensitized photo-oxygenation of (-)-vincadifformine (1) and (-)-tabersonine (3) is described. Reaction takes place through the intermediate formation of 16-hydroperoxyindolenines, which decompose to give 2,16-seco-products or which can be efficently trapped by reductants to give a new stereoselective synthesis of the 16-hydroxy-[3H]indoles (10) and (14). These compounds are the key precursors to the ebumane alkaloids vincamine (4) and △14-vincamine (6). Suitable experimental conditions give compounds (4) and (6) in good yields directly from their Aspidosperma precursor.
Dye-sensitized photo-oxygenation of the aspidosperma alkaloids vincadifformine and tabersonine. A new, convenient approach to vincamine / L. Calabi, B. Danieli, G. Lesma, G. Palmisano. - In: JOURNAL OF THE CHEMICAL SOCIETY. PERKIN TRANSACTIONS. I. - ISSN 0300-922X. - (1982), pp. 1371-1379.
Dye-sensitized photo-oxygenation of the aspidosperma alkaloids vincadifformine and tabersonine. A new, convenient approach to vincamine
B. DanieliSecondo
;G. LesmaPenultimo
;
1982
Abstract
The dye-sensitized photo-oxygenation of (-)-vincadifformine (1) and (-)-tabersonine (3) is described. Reaction takes place through the intermediate formation of 16-hydroperoxyindolenines, which decompose to give 2,16-seco-products or which can be efficently trapped by reductants to give a new stereoselective synthesis of the 16-hydroxy-[3H]indoles (10) and (14). These compounds are the key precursors to the ebumane alkaloids vincamine (4) and △14-vincamine (6). Suitable experimental conditions give compounds (4) and (6) in good yields directly from their Aspidosperma precursor.
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