Synthesis of 1,2-Oxazinanes via Hydrogen Bond Mediated [3 + 3] Cycloaddition Reactions of Oxyallyl Cations with Nitrones
作者:Lingbowei Hu、Michael Rombola、Viresh H. Rawal
DOI:10.1021/acs.orglett.8b02301
日期:2018.9.7
the development of [3 + 3] cycloaddition reactions between oxyallyl cations and nitrones to yield 1,2-oxazinane heterocycles. Oxyallyl cation intermediates, generated in situ from α-tosyloxy ketones in the presence of hexafluoro-2-propanol (HFIP), a cosolvent, and a base, are found to react with a range of nitrones to afford 1,2-oxazinanes in good to high yields. The reactions are catalyzed by hydrogen-bond
本文报道了在氧烯丙基阳离子和硝酮之间[3 + 3]环加成反应的发展,以产生1,2-恶嗪烷杂环。发现在六氟-2-丙醇(HFIP),助溶剂和碱的存在下,由α-甲苯磺酰氧基酮原位生成的草酸烯丙基阳离子中间体可与多种硝酮反应,从而提供良好的1,2-恶嗪二酮高产。该反应由氢键供体(例如苯酚和方酸酰胺)催化,观察到4-硝基苯酚的非对映选择性大大提高。