IPy2BF4 was increased, the yield of 4 was not improved. However, the use of more electrophilic conditions gave better results (Table 1, entry 6). For entries 1–5, 3 was added to a cooled solution that contained the iodinating reagent and the acid. However, in the case of entry 6, a different experimental protocol was adopted. First, the iodinating agent and the acid were mixed at À808C, and the pyridinium salts generated in the neutralization were ...
