Diastereoselective synthesis of useful building blocks by crotylation of β-branched α-methylaldehydes with potassium crotyltrifluoroborates

(Chemical Equation Presented) The diastereoselective construction of stereotriads having consecutive methyl, hydroxy, and methyl substituents was realized by the substrate-controlled crotylation of β-branched α-methylaldehydes with potassium crotyltrifluoroborates. Especially, crotylation of 2-(1,3-dithian-2-yl)propanal with potassium (E)- crotyltrifluoroborate afforded, in good yield and with excellent diastereoselectivity, a useful building block that has different and potential functional groups on both ends.