1194653-84-3Relevant academic research and scientific papers
Highly enantioselective synthesis of spiro[cyclohexanone-oxindoles] and spiro[cyclohexanone-pyrazolones] by asymmetric cascade [5+1] double Michael reactions
Wu, Bin,Chen, Jian,Li, Mei-Qiu,Zhang, Jin-Xin,Xu, Xiao-Ping,Ji, Shun-Jun,Wang, Xing-Wang
experimental part, p. 1318 - 1327 (2012/04/11)
The asymmetric catalytic synthesis of naturally occurring and biologically active spiro compounds is a challenge for modern chemical methodology. Here we report the construction of spiro compounds through cascade [5+1] double Michael reactions between divinyl ketones and N-unprotectedoxindoles or N-phenyl-protected pyrazolones catalyzed by a combination of the easily available 9-amino-9-deoxy-epi-quinine with N-Boc-D-phenylglycine. The desired multistereogenic spiro[cyclohexanone-oxindoles and -pyrazolones] were obtained with high yields (up to 98 %) andstereoselectivities (up to >20:1 dr, 99 % ee). An efficient approach to spiro compounds through cascade [5+1] double Michael reactions between divinyl ketones and oxindoles or N-protected pyrazolones in the presence of 9-amino-9-deoxy-epi-quinine and N-Boc-D-phenylglycine is reported. Multistereogenic spiro[cyclohexanone- oxindoles and -pyrazolones] are obtained with high yields (up to 98 %) and stereoselectivities (up to >20:1 dr, 99 % ee). Copyright
