Xia, Peng-Ju Sun, Yan-Hua Xiao, Jun-An Zhou, Zhao-Fang Wen, Sai-Shuai Xiong, Yu Ou, Guang-Chuan Chen, Xiao-Qing Yang, Hua Regioselectivity-Tunable Self-1,3-Dipolar [3+3] Cyclizations of Azomethine Ylides To Assemble Dispirooxindole-piperazines A series of novel 2,3- or 2,5-dispirooxindole-piperazine ring systems were efficiently constructed through the acid-promoted self-1,3-dipolar [3+3] cyclizations of azomethine ylides derived from isatin with various primary or cyclic secondary amines. Interestingly, the regioselectivity of this self-[3+3] cyclization could be effectively tuned by varying the structural features of substrates. The unprecedented 2,5-dispirooxindole-piperazine skeleton was achieved in good diastereoselectivity by employing 1,2,3,4-tetrahydroisoquinoline, while using pyrrolidine or glycine methyl ester furnished the 2,3-dispirooxindole-piperazine scaffold in excellent diastereoselectivity (only a single isomer formed). isomer;skeleton;series;Cyclization;amines;regioselectivity;azomethine ylides;cyclization;scaffold;diastereoselectivity;tetrahydroisoquinoline;pyrrolidine;substrate;cyclic;Azomethine Ylides;isatin;glycine methyl ester 2015-11-20
    https://acs.figshare.com/articles/journal_contribution/Regioselectivity_Tunable_Self_1_3_Dipolar_3_3_Cyclizations_of_Azomethine_Ylides_To_Assemble_Dispirooxindole_piperazines/2106706
10.1021/acs.joc.5b02088.s001