Thieno pyrimidines, bromination nitration

PHA457). Thieno[2,3-d]pyrimidine 89c was brominated, nitrated, and formylated at position 6 to give the 6-bromo, 6-nitro, and 6-formyl derivatives 89d, respectively (90JHC717). 

Electrophilic and nucleophilic reactions of 2-(2-thienyl)thieno[2,3-cf pyrimidine (346), prepared as shown in Scheme 99, permits a conclusion concerning the reactivity compared with that of thiophene bearing an electron deficient substituent in position 2. Both nitration and bromination primarily occur in the thiophene moiety whereas lithium organic reagents (methyllithium, butyllithium) add at carbon atom 4 (77BSF676). Bromination of (324) yields the 5- (or 6-) bromo derivative (68CR(C)(267)697). 

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