✦ LIBER ✦
Diastereofacial selectivity in ketene [2+2] cycloaddition to endocyclic enecarbamates bearing a chiral auxiliary. Synthesis of the (−)-Geissman-Waiss lactone
✍ Scribed by Paulo Cesar M.L. Miranda; Carlos Roque D. Correia
- Book ID
- 104262416
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- French
- Weight
- 201 KB
- Volume
- 40
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
The diastereofacial selectivity of enecarbamates bearing a chiral auxiliary was evaluated for the [2+2]cycloaddition with dichloroketenes. Diastereofacial selectivity ranged from zero (bornyl and menthyl) to 60% (Greene's auxiliary and 8-phenylmenthyl). Chromatography separation of the diastereomeric azacyclobutanones derived from the 8-phenylmenthyl enecarbamate permitted an enantiodivergent synthesis of the (-)-Geissman-Waiss lactone, a key intermediate in the synthesis of necine bases.