Regioselective synthesis of 1-allyl- and 1-arylmethyl uracil and thymine derivatives

2,4-Bis(trimethylsiloxy) pyrimidines with allyl halides and arylmethyl halides in 1,2-dichloroethane in the presence of I2 regioselectively provide 1-allyl-/1-arylmethyl-uracil and thymine derivatives. The secondary aryl alkyl and diaryl methyl halides with provide chiral 1-arylalkyl/1-(diarylmethyl) uracil/thymine derivatives. The procedure has been extended to the synthesis of fluorescent uracil/thymine derivatives.