Furan-Terminated <i>N</i>-Acyliminium Ion Initiated Cyclizations in Alkaloid Synthesis
作者:Steven P. Tanis、Melissa V. Deaton、Lisa A. Dixon、Mark C. McMills、Jeffrey W. Raggon、Mark A. Collins
DOI:10.1021/jo980718l
日期:1998.10.1
cyclizations for the synthesis of linearly fused alkaloid precursors (Figure 2) is presented. The outcome of the cyclization event depends on the position of furan tether attachment (2 vs 3), tether length, and furan 5-substituent (R = H, CH(3), Ar). 3-Substitutedfurans cyclized to form 6- and 7-membered ring containing furans 35-38, 50, and 51 in good to excellent yields. 2-Substituted furans closed to form