| 摘要 |
<p>Azetidinone derivatives of the formulae (Ia) <IMAGE> and/or (Ib) <IMAGE> are prepared by a1) treating a compound of the formula (IV) <IMAGE> (R is a protecting group), with an acid and reducing the compound of the formula (III) <IMAGE> obtained and eliminating the R protecting group from the diastereomeric pair of the formula (II) <IMAGE> obtained, by oxidation, or a2) reducing a compound of the formula (III), and eliminating the R protecting group from the diastereomeric pair of the formula (II), or a3) splitting off the R protecting group from the diastereomeric pair of the formula (II) and, in each of a1, a2 and a3, isolating the diastereomeric mixture of the compounds of the formulae (Ia) and (Ib) obtained, or if desired, separating the component of the formula (Ia) from the component of the formula (Ib) by selective crystallization.</p> |
