✦ LIBER ✦
Optically active cyclopropanols by samarium(II) iodide induced intramolecular reductive cyclisation of β-chloro-substituted amides.
✍ Scribed by Antoine Fadel
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 258 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0957-4166
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✦ Synopsis
Samarium diiodide promotes under mild conditions, intramolecular reductive cyclisation of /3-chloro-substituted amides, and leads with an excellent diastereomeric excess and high yield to functionalked optically active cyclopropamls.
We have recently reported that cyclopropanone hemiketal Is, readily available from sodium induced cyclisation of P-halo esters 2 in the presence of Me3SiCl. 1 underwent a one pot asymmetric Strecker synthesis to give the (R)or (S)-2.3-methanovaline 3 (R=R'= CH3) 2a.b an useful herbicide. ~JZ Unfortunately this cyclisation did not allow, access to the corresponding amino alcohol lb which in turn would constitute a more straightforward precursor of chiral methanoamino acids 3.