Total synthesis of islandic acid I methyl ester, rosellisin and rosellisin aldehyde

Total synthesis of islandic acid I methyl ester (2), rosellisin (3) and rosellisin aldehyde (4) has been accomplished starting from 4-hydroxy-5-hydroxymethyl-6-methyl-2H-pyran-2-one (9a) via formylation of (9a) with dichloromethyl methyl ether and titanium tetrachloride as a key step