Total Synthesis of Halicholactone and Neohalicholactone

Abstract

New total syntheses of the marine oxylipins halicholactone and neohalicholactone are presented. The key building blocks were synthesized utilizing chemoenzymatic methods.

Total Synthesis of Chlorinated Oxylipin Eiseniachloride B

“…[5][6][7][8][9][10][11][12][13][14] Furthermore, it has recently become clear that oxylipin is involved in the innate immunity of macroalgae, [15][16][17][18][19] and many research groups have thus focused on its complex structure and unique biological activity in various synthetic studies. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] In 2003, Kimura and colleagues discovered the novel oxylipins that contain a chlorine or iodine atom during a bioassayguided investigation of the brown alga, Eisenia bicyclis. 36) Eiseniachlorides A and B (1 and 2) are C 18 oxylipin consisting of cyclopentane and a 14-membered lactone, which corresponds to chlorohydrin biosynthesized via the nucleophilic opening of chlorine atoms to the oxirane of ecklonialactones A and B (3 and 4) isolated from the brown algae, Ecklonia stolonifera, by Kurata et al 37) and from Egregia menziesii by Gerwick and colleagues 38) (Fig.…”

“…Meanwhile, our labora-tory has also reported the synthesis of marine oxylipins and has achieved the total synthesis of both hybridalactone 40) and agardhilactone. 27,31) Herein, we describe a novel total synthesis of eiseniachloride B (2) and ecklonialactone B (4) starting from optically active lactol 5, which was the intermediate of hybridalactone. 40)…”