The synthesis of 14-membered macrocyclic ethers

As part of on ongoing study of the chemistry of macrocyclic compounds, 14-m embered macrocyclic ethers with a variety of methyl substitution patterns w ere synthesized. The preparation of these macrocyclic ethers involved eithe r the Baeyer-Villiger ring expansion of a cyclic ketone, or the macrolacton ization of a hydroxy acid to give a lactone. The lactone carbonyl was remov ed either by conversion to an intermediate thionolactone obtained by reacti on with Lawesson's reagent and reduction, or by direct reduction using a bo ron trifluoride etherate mediated sodium borohydride reaction. (C) 1999 Els evier Science Ltd. All rights reserved.