Addition of the Z‐ and E‐γ‐alkoxyallylboronates 3 and 6 to O‐benzyllactaldehyde led to various 3,4,5‐trioxygenated 1‐hexenes of arabino, xylo, ribo, and lyxo configuration. The extent of asymmetric induction amounted to 82:18 (arabino/xylo) in the addition of 3 and to 40:60 (ribo/lyxo) on addition of 6. The factors which determine the direction and extent of asymmetric induction are discussed, pointing to Cornforth‐type conformations in the transition state. Individual members of the 3,4,5‐trioxygenated hexenes were converted into 2,6‐dideoxy‐L‐hexoses of arabino, ribo, and lyxo configuration.
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Hoffmann et al. (1987) studied this question.