Ru(II)-Catalysis in preparation of sterically congested and stereochemically homogeneous heterospiranes
- 1 January 1999
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 12,p. 1677-1684
- https://doi.org/10.1039/a901913h
Abstract
Sterically highly crowded dienes may undergo RCM reactions to furnish heterocyclic bispiranes in high yields. The diene substrates were C1-bridged bis[(2R)-5-alkenyl-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazines]. The carbonyl or hydroxymethyl bridges were prepared in stereoselective reactions. A free hydroxy group in the present series was incompatible with the RCM reaction. The ring closure proceeded readily after O-methylation. The course of the stereochemical transformations has been verified by X-ray analyses.Keywords
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