Electrophilic ipso-Cyclization of N-(p-Methoxyaryl)propiolamides Involving an Electrophile-Exchange Process
摘要:
A novel electrophilic ipso-cyclization involving an electrophile-exchange process has been developed. In the presence of CuX (X = I, Br, SCN) and electrophilic fluoride reagents, a variety of N-(p-methoxyaryl)propiolamides and 4-methoxyphenyl 3-phenylpropiolate were cyclized to selectively afford the corresponding spiro[4.5]decenones in moderate to good yields. It is noteworthy that two azaquaternary tricyclic products were synthesized through a two-step pathway involving an electrophilic ipso-cyclization and then an intramolecular Heck reaction.
Electrophilic <i>ipso</i>-Cyclization of <i>N</i>-(<i>p</i>-Methoxyaryl)propiolamides Involving an Electrophile-Exchange Process
作者:Bo-Xiao Tang、Qin Yin、Ri-Yuan Tang、Jin-Heng Li
DOI:10.1021/jo8018297
日期:2008.11.21
A novel electrophilic ipso-cyclization involving an electrophile-exchange process has been developed. In the presence of CuX (X = I, Br, SCN) and electrophilic fluoride reagents, a variety of N-(p-methoxyaryl)propiolamides and 4-methoxyphenyl 3-phenylpropiolate were cyclized to selectively afford the corresponding spiro[4.5]decenones in moderate to good yields. It is noteworthy that two azaquaternary tricyclic products were synthesized through a two-step pathway involving an electrophilic ipso-cyclization and then an intramolecular Heck reaction.
Intramolecular <i>ipso</i>-Halocyclization of 4-(<i>p</i>-Unsubstituted-aryl)-1-alkynes Leading to Spiro[4,5]trienones: Scope, Application, and Mechanistic Investigations
作者:Bo-Xiao Tang、Yue-Hua Zhang、Ren-Jie Song、Dong-Jun Tang、Guo-Bo Deng、Zhi-Qiang Wang、Ye-Xiang Xie、Yuan-Zhi Xia、Jin-Heng Li
DOI:10.1021/jo300037n
日期:2012.3.16
A new, general method for the synthesis of spiro[4,5]trienores is described by the intramolecular ipso-halocyclization of 4-(p-unsubstituted-aryl)-1-alkynes. In the presence of halide electrophiles, a variety of 4-(p-unsubstituted-aryl)-1-alkynes underwent the intramolecular ipso-halocyclization with water smoothly, affording the corresponding halo-substituted spiro[4,5]trienones in moderate to good yields. The obtained spiro[4,5]trienones can be applied in constructing the azaquaternary tricyclic skeleton via Pd-catalyzed Heck reaction. Notably, the prepared spiro[4,5]trienones and azaquaternary tricycles are of importance in the areas of pharmaceuticals and agrochemicals. The mechanism of the intramolecular ipso-halocyclization reaction is also discussed according to the O-18-labeling experiments and DFT calculations.