(4-MeO)C6H4CHO in toluene byproducts: CH2CCOOCH(4-MeOC6H4)C(CH3)(CH2CHCH2); treatment of small excess (1.5 equiv.) of crude (CH2CHCH2)(Me)CCCO2CH3(CH2B(OC(CH3)2)2) with (4-MeO)C6H4CHO in toluene at 110°C. for 16-24 h;