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. 2009 Jan 12;5:1. doi: 10.3762/bjoc.5.1

Table 3.

Initial optimization studies of cyclization of arenediazonium salt 49a.

graphic file with name Beilstein_J_Org_Chem-05-01-i002.jpg
Entry Diazonium Salt Equivalents of TDAE Solvent Temperature (°C) Time Isolated Yielda (%) of
51a 52a
(i) 49a 1.0 Acetone 25 30 min 39b 40
(ii) 49a 1.5 DMF (anhydrous) 25 10 min 68c 0

aAll isolated yields were calculated on the basis of the quantity of the starting aryl amine 48a. bThe product 51a was isolated directly from the reaction mixture after auto-tautomerisation of 50a to indole 51a during storage of reaction mixture prior to flash chromatography. cThe product 51a was obtained by treatment of the intermediate exocyclic alkene 50a with p-toluenesulfonic acid monohydrate in dichloromethane at r.t. for 12 h.