“…In this procedure, the starting nitrotoluene 12 is condensed with dimethylformamide dimethyl acetal ( 31 ), usually with an added equivalent of pyrrolidine ( 88 ) (or with tripiperidinomethane alone [ 21 ]), to give the substituted aminostyrene 89 . This is then reduced, affording the desired 6-bromoindole ( 81 ) ( Scheme 41 ) [ 21 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 ]. While a variety of reducing agents have been used for the second step, buffered aqueous titanous chloride appears to be the most efficient, and overall yields of up to 77% have been reported [ 257 , 263 ].…”