Metal-Catalyzed Cycloisomerization and Tandem Oxycyclization/Hydroxylation of Alkynols: Synthesis of Nonfused, Spiranic and Fused Oxabicyclic β-Lactams
作者:Benito Alcaide、Pedro Almendros、Teresa Martínez del Campo、Rocío Carrascosa
DOI:10.1002/ejoc.201000710
日期:2010.9
2-Azetidinone-tethered alkynols, readily prepared from the corresponding aldehydes or ketones, were used as starting materials for the oxycyclization reaction catalyzed by precious metals. AgOAc exclusively affords dihydrofurans, methylenetetrahydrofurans, or methylenetetrahydro-2H-pyrans through specific 5-endo, 5-exo, or 6-exo pathways, respectively. Interestingly, in the presence of a catalytic amount of Pt"
2-氮杂环丁酮链炔醇,很容易从相应的醛或酮制备,被用作贵金属催化氧环化反应的原料。AgOAc 分别通过特定的 5-endo、5-exo 或 6-exo 途径专门提供二氢呋喃、亚甲基四氢呋喃或亚甲基四氢-2H-吡喃。有趣的是,在催化量的 Pt" 或 Au III 盐的存在下,环化反应优先通过炔醇的串联氧环化/羟基化发生,以中等至高产率提供各种非稠合、螺旋和稠合氧杂双环 β-内酰胺。此外,已经观察到可以完成串联金催化的甲氧基甲基炔基醚的环醚化/羟基化。