10.1039/b805880f
In this study, an efficient and convergent total synthetic method is proposed for the synthesis of two catechol siderophores, fulvebactin and vibriomycin, in which a molybdenum(VI) oxide-catalyzed dehydration cyclization is the key step. The researchers used N-(o,m-dialkoxybenzoyl)-L-threonine derivatives to construct the 2-(o,m-dihydroxyphenyl)oxazoline moiety at an early stage. The molybdenum(VI) oxide-catalyzed method is effective for the synthesis of oxazolines, and this study explored various protecting groups on the catechol moiety and found that the cyclic o-xylyl group showed excellent reactivity and was easy to remove. The synthesis involved Sb(OEt)3-catalyzed ester-amide transformation to selectively synthesize diamides and monoamides, and WSCI?HCl and HOAt-promoted dehydration amide formation to achieve the final assembly. The o-xylyl group was removed by hydrogenolysis to obtain the target compounds, where the longest linear sequence required 9 steps starting from 2,3-dihydroxybenzoic acid, with an overall yield of 65% for fulvebactin and 50% for vibriomycin.
10.1016/j.tetlet.2017.07.074
The study presents the first total synthesis of greensporone C, a cytotoxic 14-membered resorcylic acid lactone with potential biological activities such as cytotoxicity against certain cancer cell lines. The synthesis involved a 16-step linear sequence with a 3.3% overall yield. Key chemicals used in the study include Mitsunobu reagents for esterification to construct the macrocycle and establish the (E)-olefin geometry, benzoic acid derivatives and (R)-non-8-en-2-ol as key fragments for the synthesis, and various protecting groups and reagents such as ethoxymethyl (EOM), t-butyldimethylsilyl chloride (TBSCl), and iodobenzene diacetate for protecting and modifying functional groups. The purpose of these chemicals was to construct the complex structure of greensporone C, confirm its absolute stereochemistry, and potentially unlock its biological activities for further study and application.
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