Enantioenriched aldehydes are produced through asymmetric hydroformylation of styrene derivatives using BIBOP-type ligands. The featured example is enantioselective synthesis of 4-methyl-3,4-dihydroisocoumarin, which was prepared in a 95.1:4.9 enantiomeric ratio from asymmetric hydroformylation of ethyl 2-vinylbenzoate followed by in situ lactonization during the reduction process. The conditions are compatible with both electron-rich and electron-poor substituents.