Synthesis of chromene analogues via oxidative cleavage of 1,2-diols

One of the basic organic transformations is the oxidative cleavage of 1,2-diol, which is currently primarily carried out by stoichiometric oxidants like Pb(OAc)(4) or KMnO4, producing stoichiometric hazardous waste. The current method uses 1,2-diols as key reagents instead of benzaldehydes because it has been shown that periodic acid is an effective and mild reagent for the one-pot synthesis of pyran analogues from a variety of 1,2-diols. In this process, 1,2-diols are oxidized in situ to aldehydes, which then undergo a three-component reaction with malononitrile and phenols/4-hydroxycoumarin/dimedone to yield pyran analogues. The process is accelerated by the iodic acid produced in situ from periodic acid. The process has several appealing characteristics, including mild reaction conditions, short reaction times, broad functional group tolerance, easy product isolation, and excellent yields, use of an ecofriendly oxidant, potentially making it environmentally friendly.