Department of Chemistry , University of Chicago , 5735 South Ellis Avenue , Chicago , Illinois 60637 , United States.
Org Lett. 2018 Sep 7;20(17):5384-5388. doi: 10.1021/acs.orglett.8b02301. Epub 2018 Aug 22.
Reported herein is 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 donors such as phenols and squaramides, and dramatically higher diastereoselectivities are observed with 4-nitrophenol.
本文报道了偕氧烯阳离子与硝酮之间的[3 + 3]环加成反应，生成 1,2-噁嗪烷杂环。偕氧烯阳离子中间体由α-对甲苯氧基酮在六氟异丙醇（HFIP）、共溶剂和碱存在下原位生成，发现其与一系列硝酮反应，以良好至高的收率得到 1,2-噁嗪烷。反应由氢键供体如酚和酰亚胺酰胺催化，而 4-硝基苯酚则表现出显著更高的非对映选择性。
