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A synthesis of 1,6-dioxaspiro[4.5]dec-3-enes.

✍ Scribed by Richard Whitby; Philip Kocieński

Publisher
Elsevier Science
Year
1987
Tongue
French
Weight
205 KB
Volume
28
Category
Article
ISSN
0040-4039

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✦ Synopsis

Base-catalysed rearrangement of a 2-alkynyl-tetrahydropyran generates an allenol ether intermediate which undergoes acid-catalysed cyclisation to the 1,6-dioxaspiro[4S]dec-3-ene system.

We recently described a synthesis of the 1,7-dioxaspiro[5S]undec-4-ene system (4)' which made strategic use of the stereoselective protonation2 of the 1,3-dialkylalkoxyallene

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Spiroketal equilibration: Interconversio
Spiroketal equilibration: Interconversion of 1,6-dioxaspiro[4.4]nonanes and 1,6-dioxaspiro[4.5]decanes. Implications for the synthesis of cephalostatin 7
✍ Jae Uk Jeong; P.L. Fuchs 📂 Article 📅 1994 🏛 Elsevier Science 🌐 French ⚖ 279 KB

Acid-catalyzed equilibration of spiroketals 5SHp6 and 55Haj3 involves a two stage process whereby the 1,6-dioxaspiro]4.4]nonanes can be equilibrated under mild conditions to a pair of 1,6\_dioxaspiro[45]decanes with preservation of the adjacent C-20 methyl stereocenter. Under more forcing conditions