Pyridine based ionic fluoride for catalyzing indole and tetrazole formation

An ionic liquid of formula (I)

• or a solvate thereof, a tautomer thereof, a stereoisomer thereof, or a mixture thereof;
• wherein:
• R1 and R2 are independently selected from the group consisting of an optionally substituted alkyl, an optionally substituted cycloalkyl, an optionally substituted arylalkyl, and an optionally substituted aryl;
• R3 is selected from the group consisting of a hydrogen, an optionally substituted alkyl, an optionally substituted cycloalkyl, an optionally substituted arylalkyl, an optionally substituted aryl, an optionally substituted alkoxy, an optionally substituted alkanoyl, an optionally substituted aroyl, a halogen, a nitro, and a cyano;
• R4 and R5 are independently selected from the group consisting of a hydrogen, an optionally substituted alkyl, an optionally substituted cycloalkyl, an optionally substituted arylalkyl, and an optionally substituted aryl;
• and
• n is an integer in a range of 0-15.