Preparation and Rearrangement of <i>N</i>-Vinyl Nitrones: Synthesis of Spiroisoxazolines and Fluorene-Tethered Isoxazoles
作者:Dong-Liang Mo、Donald A. Wink、Laura L. Anderson
DOI:10.1021/ol3022885
日期:2012.10.19
N-Vinyl nitrones derived from fluorenone have been prepared via a copper-mediated coupling between fluorenoneoxime and vinyl boronic acids. These compounds undergo subsequent rearrangement and addition reactions that are distinct from the traditional [3 + 2] cycloaddition reactivity of nitrones. Thermal rearrangements of fluorenone N-vinyl nitrones give spiroisoxazolines, while treatment with alkynes
2-Alkyl-3,3-dichlorospiro[cyclopropane-1,9′-fluorene] derivatives (4) were obtained by the addition of CCl2 to 9-alkylidenefluorenes. Ringopeningreactions of 4 with bases gave enynes, butadienes, or butatrienes.