A method for a concise assembly of oxazine rings based on a Lewis acid-promoted hetero-Cope rearrangement is described. The hetero-Cope rearrangement features the first examples of the [3,3]-sigmatropic transpositions involving the nitroso group. A variety of functionalized substrates have been subjected to the reaction. The described method has a strong potential for the synthesis of marine natural products containing oxazine rings.
Strong Counteranion Effects on the Catalytic Activity of Cationic Silicon Lewis Acids in Mukaiyama Aldol and Diels−Alder Reactions
作者:Kenji Hara、Ryuto Akiyama、Masaya Sawamura
DOI:10.1021/ol052206g
日期:2005.12.1
[GRAPHICS]A toluene-coordinated silyl borate, [Et3Si(toluene)]B(C6F5)(4), demonstrated catalytic activities significantly higher than those of Me3SiOTf and Me3SiNTf2 in Mukaiyama aldol and Diels-Alder reactions.