Mild and Efficient Preparation of Phytosteryl Amino Acid Ester Hydrochlorides and Their Emulsifying Properties

The aim of this work was to produce a series of phytosteryl amino acid ester hydrochlorides by a two-step method, which involved esterification of phytosterols with N- tert-butoxycarbonyl (BOC) amino acid and deprotection of the BOC group. The highest yield of over 95.0% was obtained when the catalysts were the mixtures of 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochlide, 4-dimethylaminopyridine, and triethylamine. It was found that batch charging of the reactants and catalysts was conducive to improving the yield. In addition, over 99.0% of the BOC group deprotection degree was achieved using the HCl/ethyl acetate deprotection method. All of the compounds were characterized by fourier transform infrared spectroscopy, mass spectroscopy, and nuclear magnetic resonance spectroscopy. The emulsifying properties of phytosterols and phytosteryl amino acid ester hydrochlorides were also investigated. The results showed higher emulsifying properties of phytosteryl amino acid ester hydrochlorides, which could favor its wide application in food systems.

Total synthesis of (+)-trienomycins A and F via C-C bond-forming hydrogenation and transfer hydrogenation

The triene-containing C17-benzene ansamycins trienomycins A and F were prepared in 16 steps (longest linear sequence, LLS) and 28 total steps. The C11-C13 stereotriad was generated via enantioselective Ru-catalyzed alcohol CH syn crotylation followed by chelation-controlled carbonyl dienylation. Enantioselective Rh-catalyzed acetylene-aldehyde reductive coupling mediated by gaseous H2 was used to form a diene that ultimately was subjected to diene-diene ring closing metathesis to form the macrocycle. The present approach is 14 steps shorter (LLS) than the prior syntheses of trienomycins A and F, and 8 steps shorter than any prior synthesis of a triene-containing C17-benzene ansamycin.