TMSI mediated Prins-type cyclization of ketones with homoallylic and homopropargylic alcohol: synthesis of 2,2-disubstituted-, spirocyclic-4-iodo-tetrahydropyrans and 5,6-dihydro-2H-pyrans

The Prins-type cyclization of ketones with homoallylic and homopropargylic alcohols in the presence of TMSI generated in situ from TMSCl and NaI produced 2,2-disubstituted- or spirocyclic-4-iodo-tetrahydropyrans and spirocyclic-4-iodo-5,6-dihydro-2H-pyrans in good yields. These iodopyrans are reported for the first time.