Intramolecular allylboration of γ-(ω-formylalkoxy)allylboronates for syntheses of trans- or cis-2-(ethenyl)tetrahydropyran-3-ol and 2-(ethenyl)oxepan-3-ol
give 3-alkoxy-1-alkenylboronates 5. The latter gave (E)-3-alkoxyallylboronates (8: (E)-(MeO)2CHCH2(CH2)nCH2OCHCHCH2Bpin, n=1–3) when they were subjected to iridium-catalyzed isomerization of the double bond. The corresponding (Z)-isomers 10 were synthesized by nickel-catalyzed isomerization of 5. Both allylboronates underwent intramolecular allylboration leading to the formation of trans-2-(ethen
Stereoselective synthesis of alcohols. Part LIII. (E)-γ-Alkoxyallylboronates: generation and application in intramolecular allylboration reactions
作者:Reinhard W. Hoffmann、Jochen Krüger、David Brückner
DOI:10.1039/b003551n
日期:——
subjected to the Matteson–Brown homologation with LiCH2Cl, give rise to the (E)-γ-alkoxyallylboronates 3 in good yield. This reaction sequence has been used to generate the (E)-γ-alkoxyallylboronates 14, 21, 26 and 31, which were the starting point for intramolecularallylborationreactions leading to the trans-disubstituted tetrahydropyrans 8 and 22, as well as hydrooxepans 27 and 32.