540770-17-0Relevant academic research and scientific papers
Asymmetric total synthesis of the gastroprotective microbial agent AI-77-B
Ghosh, Arun K.,Bischoff, Alexander,Cappiello, John
, p. 821 - 832 (2003)
An enantioselective total synthesis of the pseudopeptide microbial agent AI-77-B, which has shown potent antiulcerogenic properties, is described. The synthesis is convergent and involves the assembly of a dihydroisocoumarin fragment and a hydroxy amino acid. The dihydroisocoumarin derivative was synthesised by means of a Diels-Alder reaction between 1-methoxy-1,3-cyclohexadiene and an alkynyl ester derivative as the dienophile. The alkynyl ester was obtained stereoselectively by two different synthetic routes: (1) A stereoselective allylation of leucinal, and (2) a titanium enolate-mediated anti-aldol reaction with trichlorobutyraldehyde, a novel homopropargylaldehyde equivalent. The stereocentres of the hydroxy amino acid moiety were generated through a titanium enolate-mediated syn-aldol reaction, Curtius rearrangement, and application of Dondoni's aldehyde homologation. Condensation of the dihydroisocoumarin and hydroxy amino acid moieties and subsequent removal of the protecting groups furnished optically active AI-77-B. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
