| 摘要 |
<p>Process for the preparation of a compound of formula (VI), comprising the steps of: reacting a compound of general formula (I) with a ring-opening agent to provide a compound having general formula (II); protecting the hydroxy groups of the thus formed compound (II) with a pre-determined protective agent in order to substantially retard the reactivity thereof and provide a compound having general formula (III) or (VII), wherein the protective agent retards the reactivity of compound (II) by replacing the hydrogen atom of at least one of the hydroxy groups thereof with a carbon terminated group, whereby, in the case of compound (III) at least one of R<3> and R<4> is not hydrogen; reacting compound (III) and/or (VII) with an alkylating agent of formula R<7>X to obtain a compound having formula (IV) or (VIII) respectively, wherein R<7> preferably represents a methyl or ethyl group and X represents a halide, preferably chlorine, bromine or iodine; hydrolyzing the protective groups R<3>, R<4> and R<5>, R<6> of compounds (IV) and (VIII) respectively to obtain a compound of formula (V); relactonizing compound (V) to yield compound (VI).</p> |
