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. Author manuscript; available in PMC: 2014 Jul 8.
Published in final edited form as: Molecules. 2013 Nov 19;18(11):14306–14319. doi: 10.3390/molecules181114306

Table 3.

Synthesis of trimethyl-5-sulfo-3H-indolium derivatives (Discover SP CEM).

Entry R Time (min) Temp (°C) Avg. Yield (%) Lit. time (hr) Lit. Yield (%) MP (°C)
Sulfonate
14 CH3 30 130 84 24 82 [14] 253
15 CH2CH3 30 130 67 24 95 [14] 224–229
16 (CH2)2CH3 30 150 63 24 98 [14] 208–211
17 (CH2)3CH3 35 155 58 24 96 [14] 145–149
18 (CH2)2OH 5 125 69 N/A N/A 255–260
19 (CH2)5CO2H 30, 15 150 72 48 75 [14] 169–172
Indolenine
20 (CH2)3CH3 15 140 71 24 82 [28] 105–110