Synthesis of New Functionalized 2-Alkylsulfanyl-5-(1H-indol-2-yl)-1,3,4- Oxadiazole and a Facile Thio-Aza-Claisen Rearrangement of the S-Allyl Analog

Title: Synthesis of New Functionalized 2-Alkylsulfanyl-5-(1H-indol-2-yl)-1,3,4- Oxadiazole and a Facile Thio-Aza-Claisen Rearrangement of the S-Allyl Analog

Volume: 6 Issue: 6

Author(s): El Sayed H. El Ashry, El Sayed H. El Tamany, Mohy El Din Abd El Fattah, Mohamed R.E. Aly and Ahmed T.A. Boraei

Affiliation:

Keywords: Indoles, oxadiazoles, indolyloxadiazoles, thio-aza-Claisen rearrangement, allylic rearrangement

Abstract: The S-alkylated indolyloxadiazoles 2a-l were obtained regioselectively by alkylation of 5-(1H-indol-2-yl)- 1,3,4-oxadiazole-2(3H)-thione 1, using TEA as acid scavenger. Alkylation of 1 with 1-bromopropane, 1-bromobutane, 1- bromoundecan, in the presence of K2CO3, yielded the N-alkylated products 3i-j,m in addition to the S-alkylated analogs 2i-j,m. A facile thio-aza-Claisen rearrangement (S??N allylic rearrangement) of the S-allyl-oxadiazole 2k to the N-allyl analog 3k was achieved in excellent yield. Further allylation of 2k and 3k in the presence of K2CO3 led to allylation of the NH indole ring producing 5 and 6, respectively. Benzylation of 1 in the presence of K2CO3 yielded 7 which resisted the S→N migration of the benzyl group. The 1H NMR, 13C NMR and mass spectra confirmed the structures and differentiated between the N- and S-alkylated products.

Cite this article as:

El Ashry H. El Sayed, El Tamany H. El Sayed, El Fattah El Din Abd Mohy, Aly R.E. Mohamed and Boraei T.A. Ahmed, Synthesis of New Functionalized 2-Alkylsulfanyl-5-(1H-indol-2-yl)-1,3,4- Oxadiazole and a Facile Thio-Aza-Claisen Rearrangement of the S-Allyl Analog, Letters in Organic Chemistry 2009; 6 (6) . https://dx.doi.org/10.2174/157017809789124902