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Updated: Nov 26, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
The allylic oxidation of tigliane esters
Hawraz Ibrahim M Amin1, Chiara Maioli1, Giuseppina Chianese2
1Università del Piemonte Orientale, Dipartimento di Scienze del Farmaco, Largo Donegani 2, 28100 Novara, Italy.
Abstract:
As part of a study on the structure-activity relationships of the anticancer agent tigilanol tiglate (EBC-46, 2), the allylic oxidation of phorbol triacetate (1c) and of the acetonide of its 3αH-dihydroderivative (5) was investigated. The aim was to introduce an oxygen function at C-5 en route to point-like analogues of 2, but functionalization of C-10 was instead observed. This was followed by oxidative fragmentation of ring B to the 9,10-secotigliane derivative 6 and oxidation of the endocyclic Δ6 double bond to the C-6/C-10 oxygen bridged 7-oxotigliane 7. Despite the over-functionalization of ring B, these observations suggest the possibility to modify positions overlooked in the oxidase phase of tigliane biosynthesis and explore novel areas of the phorbol chemical space.
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