Styrene derivatives underwent dehydroborylation with naphthalene-1,8-diaminatoborane [(dan)BH] in the presence of a cationic rhodium complex, giving beta-borylstyrene derivatives in good yields. Thus prepared beta-borylstyrenes bearing a chlorine or B(pin) group on their aromatic rings were utilized for the synthesis of highly conjugated molecules through stepwise cross-coupling, taking advantage of the dan group as an effective protective group for a boronyl group.