A Practical Synthesis of Homoallylic Diene Halides: Versatile Synthons for the Preparation of the Taxane A-Ring System

Abstract

A concise and efficient synthesis of two homoallylic halides, which are useful precursors for the preparation of the taxane A-ring system is reported. Contrary to the synthetic routes reported in the literature, this procedure does not employ expensive tetramethylethylene as a starting material. The synthetic route uses readily available and inexpensive ethyl acetoacetate, 1,2-dibromoethane, methyltriphenylphosphonium iodide and methylmagnesium bromide as starting materials. The key step in the synthesis is the acid-mediated ring opening of a cyclopropyl tertiary alcohol to afford the corresponding homoallylic diene halides. The corresponding Grignard reagent, derived from the bromide, is used in the synthesis of an enone previously used as a precursor of taxadienone by reaction with the enol ethyl ether of 1,3-cyclohexanedione.

Key words

taxanes - diene - cyclopropyl alcohol - Diels–Alder

Publication History

Received: 08 September 2023

Accepted after revision: 21 November 2023

Accepted Manuscript online:
21 November 2023

Article published online:
13 December 2023

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