Macrocycles via Doebner Reaction Followed by Macrolactonization

The synthesis of 14 different macrocycles is reported. Upon reacting different formylphenoxyacetic acid derivatives with 5-aminopentanol and a diketo compound, eight different Doebner product intermediates were obtained. These intermediates were then subjected to cyclization by using polymer-bound carbodiimide to give macrolactones. Both the monomers and the dimers could be isolated and characterized. In some cases trimers could be seen from the HPLC-MS. The ratios and distribution of the different-sized rings are discussed.