Regioselective nucleophilic ring opening of epoxides and aziridines derived from homoallylic alcohols

✍ Scribed by David Tanner; Thomas Groth

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 468 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)10053-9

✦ Synopsis

The regioselectivity of nucleophilic ring opening of some 3,4-epoxy and 3,4-aziridino alcohols has been studied. The nucleophiles chosen were complex hydrides (LiAIH4, Red-Al and DIBAL) and Lipshutz-or Gilman-type organocuprate reagents. The C-4 substituent in the substrates was varied in order to study steric and electronic effects on the ring opening reactions.

For alkyl substituents at C-4, most of the results can be explained on the basis of intramolecular delivery of the nucleophile to C-3 via a six-membered transition state, leading to 1,4-diols or 1,4amino alcohol derivatives. In general, the epoxy alcohols gave poorer regioselectivity than the Ntosyl aziridino alcohols, for which selectivities of >95:5 were routinely obtained. The activating effect of a phenyl group at C-4 led to a switch in regiochemistry, with the 1,3-diol or 1,3-amino alcohol derivative as the major product.