pyridinium p-toluenesulfonate in acetonitrile T=20 - 60°C; 72 h; Inert atmosphere;

trifluoroacetic acid; (S)-5,6-dimethyl-2-(pyrrolidin-2-yl)-1H-benzo[d]imidazole in tetrahydrofuran Robinson annelation; Title compound not separated from byproducts;

1: 78 percent / dppe; BSA; sodium acetate / allyl palladium chloride dimer / tetrahydrofuran / 70 °C 2: 54 percent / H2O / 20 °C 3: (S)-5,6-dimethyl-2-(pyrrolidin-2-yl)-1H-benzimidazole; TFA / tetrahydrofuran View Scheme

1: 54 percent / H2O / 20 °C 2: (S)-5,6-dimethyl-2-(pyrrolidin-2-yl)-1H-benzimidazole; TFA / tetrahydrofuran View Scheme

1: bis(η3-allyl-μ-chloropalladium(II)); 1,2-bis-(diphenylphosphino)ethane; N,O-bis-(trimethylsilyl)-acetamide; sodium acetate / tetrahydrofuran / 40 h / 70 °C / |Inert atmosphere 2: water; acetic acid / 4 h / 100 °C 3: R-(+)-prolinamide; pyridinium p-toluenesulfonate / acetonitrile / 12 h / 80 °C / |Inert atmosphere View Scheme

1: water; acetic acid / 4 h / 100 °C 2: R-(+)-prolinamide; pyridinium p-toluenesulfonate / acetonitrile / 12 h / 80 °C / |Inert atmosphere View Scheme