Regioselective Mukaiyama hydroperoxysilylation of 2-alkyl- or 2-aryl-prop-2-en-1-ols: application to a new synthesis of 1,2,4-trioxanes

Co(II)-mediated peroxysilylation of allylic alcohols 6 or 9 regioselectively provides peroxysilyl alcohols 7 and 10 in good yield. Reaction of these peroxysilyl alcohols with aldehydes or ketones provides target 1,2,4-trioxanes in good to excellent yields. The sequence of Markovnikov hydroperoxysilylation and subsequent reaction with a carbonyl compound can also be readily achieved in a one-pot procedure. Significantly, easily prepared trioxanes 11a and 11b have potent in vitro antimalarial activity versus chloroquine resistant K1 Plasmodium falciparum.