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Chiral Lactols, XIV. Stereoselective Fusion of Five-Membered Ring Lactols to the Bornane Ring System

✍ Scribed by Noe, Christian R. ;Knollmüller, Max ;Gärtner, Peter ;Mereiter, Kurt ;Steinbauer, Gerhard

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
748 KB
Volume
1996
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

Condensation of d‐camphor (b) with diethyl oxalate and subsequent ester hydrolysis yielded camphoroxalic acid 3. endo‐Fused lactone 9 was obtained by reduction of 3 with zinc followed by reduction with NaBH~4~ and ring closure with H~2~SO~4~. exo‐Fused lactone 16, the crystal structure of which was determined, was prepared by reduction of 3 with NaBH~4~ under basic conditions followed by catalytic hydrogenation and ring closure with HCl. Reduction of 9 and 16 with DI‐BALH and application of acidic work‐up conditions yielded the self‐condensed reduction products (lactol anhydrides) 10 and 17, which are useful reagents in racemate resolution and stereoselective synthesis.

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An Improved Method for the endo-Fusion o
An Improved Method for the endo-Fusion of Five-Membered Ring Lactones to the Bornane Ring System
✍ Max Knollmüller; Peter Gärtner; Mathias Ferencic; Christian R. Noe; Kurt Mereite 📂 Article 📅 1998 🏛 John Wiley and Sons 🌐 English ⚖ 154 KB 👁 2 views

endo-Fused lactone 3 was obtained in high yield from the mechanism of its formation and reactivity were investigated. Lactone 3 serves as key intermediate for lactol 1 which is a camphoracetic acid 2 with thionyl chloride and a subsequent reduction of intermediate 5 with tributyltin hydride. The use