Lewis acid or Brønsted acid catalyzed reactions of vinylidene cyclopropanes with activated carbon-nitrogen, nitrogen-nitrogen, and iodine-nitrogen double-bond-containing compounds.
Lewis acid or Brønsted acid catalyzed reactions of vinylidene cyclopropanes (VDCPs), 1, with activated carbon-nitrogen, nitrogen-nitrogen, and iodine-nitrogen double-bond-containing compounds have been thoroughly investigated. We found that pyrrolidine and 1,2,3,4-tetrahydroquinoline derivatives can be formed in good yields in the reactions of VDCPs 1 with ethyl (arylimino)acetates 2 by a [3+2] cycloaddition or intramolecular Friedel-Crafts reaction pathway. Based on these results, we found that activated carbon-nitrogen and nitrogen-nitrogen double-bond-containing compounds, such as N-toluene-4-sulfonyl (N-Ts) imines 5 and diisopropylazodicarboxylate (7), can also react with VDCPs 1 to give [3+2] cycloaddition products in moderate to good yields in the presence of a Lewis acid. When N-tert-butoxycarbonyl aldimine 9 was used as the substrate, six-membered cycloaddition products 10 and 11 were formed in moderate yields in the presence of a Brønsted acid, trifluoromethanesulfonic acid (TfOH). The reactions of VDCPs 1 with N-Ts-iminophenyliodinane (12) were also carried out in the presence of (CuOTf)(2)C(6)H(6) and it was found that nitrogen-containing indene derivatives 13 were obtained, rather than the aziridination products. Plausible mechanisms for all of these transformations are discussed, based on the obtained results.
Lu
Jian-Mei
JM
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai, China.
Zhu
Zhi-Bin
ZB
Shi
Min
M