Efficient synthesis of indoles using [3,3]-sigmatropic rearrangement of N-trifluoroacetyl enehydrazines
摘要:
[3,3]-Sigmatropic rearrangement of N-triflluoroacetyl enehydrazines provides a novel method for the construction of indoles. N-Trifluoroacetyl enehydrazine having a cyclopentene ring smoothly underwent [3,3]-sign-tatropic rearrangement followed by cyclization to give indolines in excellent yield. On the other hand, both cyclohexenyl N-trifluoroacetyl enchydrazine and acyclic N-trifluoroacetyl enehydrazine gave indoles in good yield. Additionally, the substituent effect on the benzene ring was also studied. The rearrangement of N-trifluoroacetyl enchydrazines proceeded smoothly even Linder either aqueous or solvent-free conditions. (c) 2006 Elsevier Ltd. All rights reserved.
Michael Addition–Aromatization Reaction of Dienylimines Bearing a Leaving Group and Its Application to the Preparation of Thiol-Selective Labeling Reagents Capable of Forming Strong Carbon–Sulfur Bonds
The reaction of a dienylimine with thiols was found to proceed smoothly to afford the corresponding indolines bearing aromatic carbon-sulfur bonds as a result of a Michael addition-aromatization sequence. Furthermore, this reaction was applied to the development of fluorogenic dienylimines that could be used as thiol-selective fluorescent labeling reagents.