Abstract Starting from 3-methoxy-1, 2-butadiene (12) both E-and Z-γ- methoxycrotylboronates 10 and 11 were prepared in isomeric purities of 85–90%. By addition of the E-isomer 10 to aldehydes the homoallyl alcohols 5 were obtained in high diastereomeric purity. Addition to the lactaldehyde derivatives 21 unexpectedly led to the cyclopropylcarbinols 24 as main products.
