From the point of view of peptide-based therapeutics, incorporation of some linkages into a biologically active peptide is widely used for fixation of its active conformation and suppression of the enzymatic degradation. For instance, side chain bridging via disulfide, hydrocarbon (stapled peptide [1]), lactone or lactam is often employed for the fixation. To prepare stapled peptides, Ru-catalyzed olefin metathesis of the resin-bound olefin containing peptides is employed, but yield is sometimes quite low. On the other hand, the synthesis of lactone or lactam bridged peptides require laborious chemoselective deprotection of protections on hydroxyl, amino and carboxylic groups and condensation of these free functional groups. In order to exclude these complicated steps, we launched on development of a new methodology for the synthesis of lactam-bridged peptides between side chains of lysine and glutamic acid using olefin metathesis followed by reduction of the resulting olefin. Moreover, improvement of the efficiency of the olefin metathesis was also attempted. Recently, efficient liquid-phase peptide synthesis using aliphatic chain linker, AJIPHASE^®, was reported [2]. In contrast to standard solid-phase peptide synthesis, reaction of a peptide on the AJIPHASE^® proceeds efficiently in homogeneous system and a generated product can be precipitated after the reaction. We expected that reaction efficiency would be improved dramatically by the use of AJIPHASE^®. In this presentation, we report a new methodology to access to lactam-bridged peptides between side chains of a lysine and a glutamic acid involving olefin metathesis followed by reduction of the resulting olefin.