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A highly stereoselective synthesis of (E)-1,5-syn-diols 6 is described. The kinetically controlled hydroboration of allenyltrifluoroborate 8 with Soderquist borane 2 provides the (Z)-allylic trifluoroborate 9, which undergoes sequential allylboration with two different aldehydes to provide (E)-1,5-syn-diols 6 in 72−98% yields with >95% ee and >20:1 dr. Application of this method to the synthesis of the tetrafibricin C(23)−C(40) fragment 19 is described.