171201-21-1Relevant articles and documents
Establishing Consensus Stereostructures for the Naphthoquinonopyrano-γ-lactone Natural Products (–)-Arizonin B1 and (–)-Arizonin C1 by Total Syntheses. Diastereocontrol of Oxa-Pictet–Spengler Cyclizations by Protective-Group Optimization
Neumeyer, Markus,Brückner, Reinhard
, p. 2512 - 2539 (2017)
Previous total syntheses of arizonin C1 (4) led to opposite assignments of its absolute configuration. Here, we report the fourth total synthesis thereof. In addition, we disclose the first total synthesis of arizonin B1 (3) proceeding differently than via arizonin C1. The stereocenters of the two targets stemmed from an asymmetric dihydroxylation and an ensuing oxa-Pictet–Spengler cyclization. Their configurations were in line with Fernandes' assignments. Protective-group variation in the substrate modulated the diastereoselectivity of the Pictet–Spengler cyclization between 77:23 in favor of a trans disubstitution at C-3a vs. C-5 – used for preparing the natural (–)-arizonins C1 and B1 – and 100:0 in favor of a cis disubstitution – exploited for synthesizing the unnatural (+)-5-epi-arizonins C1 and B1. All naphthalenes of the present study were derived from the (benzyloxy)methoxynaphthalenediol 19. It resulted from a Diels–Alder reaction of the aryne 17a with the siloxyfuran 18a.
Catalytic Enantioselective Total Synthesis of (+)-Lycoperdic Acid
Kortet, Sami,Claraz, Aurélie,Pihko, Petri M.
supporting information, p. 3010 - 3013 (2020/04/10)
A concise enantio- and stereocontrolled synthesis of (+)-lycoperdic acid is presented. The stereochemical control is based on iminium-catalyzed Mukaiyama-Michael reaction and enamine-catalyzed organocatalytic α-chlorination steps. The amino group was introduced by azide displacement, affording the final stereochemistry of (+)-lycoperdic acid. Penultimate hydrogenation and hydrolysis afforded pure (+)-lycoperdic acid in seven steps from a known silyloxyfuran.
Cyclopropanation of (E)-Dehydroaspartic Acid Esters with Furan Derivatives: The Synthesis of Highly Functionalized α-2,3-Methanoamino Acid Esters
Manabe, Atsushi,Matsumoto, Ryotaro,Shinada, Tetsuro
supporting information, p. 1710 - 1714 (2015/07/20)
Highly functionalized α-2,3-methanoamino acid esters were prepared by the cyclopropanation of dehydroaspartic acid esters with 2-methoxyfuran or 2-siloxyfuran derivatives. These reactions proceed smoothly in the absence of any catalysts, bases, additives, or solvents.