194865-43-5Relevant academic research and scientific papers
Total syntheses of surinone B, alatanones A–B, and trineurone A
Gundoju, Narayana Rao,Bokam, Ramesh,Yalavarthi, Nageswara Rao,Buddana, Sudheer Kumar,Prakasham,Ponnapalli, Mangala Gowri
, p. 1 - 8 (2018)
The total syntheses of four polyketides, surinone B (1), alatanones A–B (2–3), and trineurone A (4) were accomplished through an efficient and unified strategy via one-pot C-acylation reaction coupling 1,3-cyclohexadiones with EDC-activated acids under mild conditions. Alatanone A (2) was found to be a potent anti-microbial agent against Gram-positive and Gram-negative bacteria with MIC 31.25?μg/ml while alatanone B (3) was found to be a potent anti-fungal agent against Cladosporium cladosporioides with MIC 62.5?μg/ml compared to cycloheximide MIC 125?μg/ml. Our methodology allows performing kilogram scale of these scarce polyketides for the development of new antimicrobials.
Synthesis of antifungal alatanone and trineurone polyketides
Lewis, Alexander R.,Reber, Keith P.
supporting information, p. 1083 - 1086 (2018/03/23)
The antifungal polyketides alatanones A and B and trineurones A–E have been synthesized using a one-pot C-acylation reaction coupling 1,3-cyclohexanediones with the appropriate carboxylic acids. This key transformation is believed to proceed via initial carbodiimide-mediated O-acylation followed by a DMAP-catalyzed Claisen–Haase rearrangement, resulting in O to C acyl migration.
Operationally simple and highly (E)-styrenyl-selective heck reactions of electronically nonbiased olefins
Werner, Erik W.,Sigman, Matthew S.
supporting information; experimental part, p. 9692 - 9695 (2011/08/06)
Simple, mild, and efficient conditions are reported for a Pd 0-catalyzed Heck reaction that delivers high yields and selectivity for (E)-styrenyl products using electronically nonbiased olefin substrates bearing a range of useful functionality. Preliminary mechanistic studies demonstrate that the σ-donating DMA solvent is crucial for high selectivity. Further studies suggest that the catalyst distinguishes between β-hydrogens on the basis of their relative hydridic character, in contrast to previously reported PdII-catalyzed oxidative reaction conditions.
Palladium-Catalyzed Isomerization of Aryl-Substituted Epoxides: A Selective Synthesis of Substituted Benzylic Aldehydes and Ketones
Kulasegaram, Sanjitha,Kulawiec, Robert J.
, p. 6547 - 6561 (2007/10/03)
Aryl-substituted epoxides bearing multiple methyl substituants on the epoxide ring isomerize in the presence of 5 mol % Pd(OAc)2/PR3 (R = n-Bu, Ph) to form the corresponding benzylic aldehyde or ketone, with complete regioselectivity for the carbonyl compound formed via cleavage of the benzylic C-O bond. No allylic alcohols or products arising from alkyl migration are observed. Rapid reaction rates and nearly quantitative yields are obtained, even with highly sterically hindered epoxides, using tri-n-butylphosphine as ligand and tert-butyl alcohol as solvent. 2-Aryl-substituted epoxides with two methyl substituents on C3 are completely unreactive, consistent with an oxidative addition/β-hydride elimination mechanism. Catalyst variation studies show that both Pd(OAc)2 and PR3 are essential for optimal activity and that palladium catalysts formed in this manner are superior to other Pd(0) catalysts (e.g., Pd(PPh3)4). The reactivity of catalytic Pd(OAc)2/PR3 toward multiply-substituted epoxides is compared to traditional Lewis acid catalysts; the former is found to be much more selective for isomerization without skeletal rearrangement. A mechanistic rationale involving turnover-limiting SN2-like attack of Pd(0) at the benzylic carbon is proposed.
