1: 5-fluoro-1-(trimethylsilyl)-2-(trimethylsilyloxy)-1H-indole; 5-formyl-2,4-dimethyl-1H-pyrrole-3-carboxylic acid (2-diethylamino-ethyl)-amide With trimethylsilyl trifluoromethanesulfonate in acetonitrile 13 h; Reflux; 2: (-)-(S)-hydroxybutanedioic acid in methanol; acetonitrile T=20°C; 22 h;

1: trimethylsilyl trifluoromethanesulfonate / N,N-dimethyl-formamide; acetonitrile / Reflux 2: methanol / 8 h / 25 °C / Inert atmosphere View Scheme

1: 5-fluoro-1-(trimethylsilyl)-2-(trimethylsilyloxy)-1H-indole With 1,1,1,3,3,3-hexamethyl-disilazane in acetonitrile 0.25 h; 2: 5-formyl-2,4-dimethyl-1H-pyrrole-3-carboxylic acid With trifluorormethanesulfonic acid

1.1: 1,1,1,3,3,3-hexamethyl-disilazane / trifluorormethanesulfonic acid / acetonitrile / 48 h / 20 - 65 °C 2.1: N-ethyl-N,N-diisopropylamine / N,N-dimethyl-formamide / 0.17 h 2.2: 25 °C 3.1: N,N-dimethyl-formamide / 25 °C View Scheme

trimethylsilyl trifluoromethanesulfonate in N,N-dimethyl-formamide; acetonitrile Reflux; Product distribution / selectivity;