Processes for preparing antiviral compounds

A method for preparing a compound of formula (I-a), stereoisomer thereof, or mixture of stereoisomers thereof:

• comprising the steps of:
• (a) cyclizing a compound of formula (L):
• under conditions sufficient to yield a compound of formula (K):
• and
• (b) brominating the compound of formula (K) under conditions sufficient to yield a compound of formula (I-a),
• wherein Z is hydrogen, halo, —OSO2R1, —BF3−, —B(OR2)2, —CO2H, or —NR13 wherein R1 is alkyl, haloalkyl, aryl or substituted aryl, and R2 is alkyl.