Intramolecular cyclization with nitrenium ions generated by treatment of N-acylaminophthalimides with hypervalent iodine compounds: formation of lactams and spiro-fused lactams.
N-Phthalimido-N-acylnitrenium ions are generated from N-acylaminophthalimides, a new class of precursors, by treatment with hypervalent iodine compounds (PIFA and HTIB). In HFIP, the nitrenium ions undergo intramolecular electrophilic substitution reactions to afford N-aminonitrogen heterocycles in high yields. In TFEA, spirodienones bearing the 1-azaspiro[4.5]decane skeleton are obtained by treatment of N-phthalimido-3-(4-halogenophenyl)propanamides with HTIB as a result of ipso attack of the intermediate nitrenium ion. Similarly, using PIFA in TFEA, ipso cyclization of unactivated benzenoid compounds occurs to afford spirodiene derivatives. This involves loss of aromaticity despite the absence of other activating substituents on the phenyl group.
Kikugawa
Yasuo
Y
Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan. kikugawa@josai.ac.jp
Nagashima
Akira
A
Sakamoto
Takeshi
T
Miyazawa
Etsuko
E
Shiiya
Megumi
M
D007202:Indicators and Reagents; D007455:Iodine; D007769:Lactams / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D010797:Phthalimides; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D007202:Indicators and Reagents; D007769:Lactams; D010797:Phthalimides; D013141:Spiro Compounds; D007455:Iodine