Dimethyl and diphenylsilyl acetals of structure (3) are convenient reagents for determining the enantiomeric purity of alcohols by n.m.r. spectroscopy.
Full details of the enantioselective four‐step and five‐step total syntheses of (−)‐chaetominine from D‐Trp and L‐Trp are described. Featuring an oxidative double cyclization reaction, and tandem C14 epimerization‐lactamization reactions as key steps, the method provides a rapid access to (−)‐chaetominine (6a) and analogues. The total syntheses of (−)‐chaetominine (6a) are so far the most concise and efficient. Through comprehensive investigation, the stereochemical requirements for the double cyclization reaction were revealed, and the confusion regarding physicochemical properties of this natural product was clarified. Moreover, short pathways to complexity generation, a scenarios revealed for the biosynthesis of fungal peptidyl alkaloid multi‐cyclic scaffolds, have been validated through the chemical synthesis. On the basis of these findings, a plausible biosynthetic pathway for (−)‐chaetominine (6a) was suggested.
The total synthesis of the alkaloid (-)-chaetominine (1) has been achieved in four steps with an overall yield of 33.4%. Key features of our strategy include a one-pot cascade indole epoxidation - epoxide ring-opening cyclization - lactamization reaction sequence, and the use of a nitro group as a latent amino group for the one-pot construction of the quinazolinone ring. This constitutes a step economical, redox economical and protecting group-free total synthesis.
We describe efficient and flexible enantioselective syntheses of the active enantiomers of the pheromones of pine sawflies, including the species Diprion jingyuanensis, their homologs and, stereoisomers, as well as those identified from the Chinese species Diprion jingyuanensis, i.e., 126. A total of 48 compounds, including acetates 78101 and propanoates 102125, have been synthesized. Our general approach towards these compounds originated from the commercially available chirons diethyl (S)- and (R)-malates, as well as ethyl (R)-3-hydroxybutanoate. The Seebach asymmetric methylation was employed in a key step to control additional configuration.National Basic Research Program (973 Program) of China [2010CB833200]; NSF of China [20832005, 21072160]; Natural Science Foundation of Fujian Province of China [2011J01054
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.