Synthesis and characterization of γ-acyloxyl-ε-caprolactones.

Abstract

ε-Caprolactone (ECL) and its derivatives are widely used in the synthesis of useful polymers. Reported herein is the gram-scale synthesis of a series of ECL derivatives with an exocyclic acyloxyl substituent at the 4- or γ-position. Of the eight compounds included, six are previously unreported, and one has conflicting characterization data. A full suite of NMR data (¹H, ¹³C, COSY, HMBC, and HMQC) is provided for all previously unreported lactones, with NOESY in select cases. This allows detailed assignment of each resolved signal and determination of conformation. Additionally, the standard characterization of intermediates is provided along with statistics on average reaction yields. This work will support the proper characterization of polymers synthesized with these monomers, especially polymers with complex sequences where structure-property relationships are critical.