Solid-phase synthesis of 6,7-cycloalkane-fused 1,4-diazepane-2,5-diones via a cyclization/release strategy

A solid-phase synthesis procedure for the parallel preparation of 6,7-cycloalkane-fused 1,4-diazepane-2,5-diones is described. The methodology applies alpha- and alicyclic beta-amino acid building blocks to construct the seven-membered heterocyclic core, while alcohols are used for further skeletal decoration. The use of a cyclization/release strategy permits the isolation of the target cyclic alpha,beta-dipeptides in good crude purities and generally moderate to good yields. A 26-membered model library is reported and NMR spectroscopical data are used to describe the overall conformational behaviour of the obtained homodiketopiperazines. (C) 2015 Elsevier Ltd. All rights reserved