1211-57-0Relevant articles and documents
Luquilloamides, Cytotoxic Lipopeptides from a Puerto Rican Collection of the Filamentous Marine Cyanobacterium Oscillatoria sp.
Boudreau, Paul D.,Choi, Hyukjae,Gerwick, William H.,Kim, Geum Jin,Mascuch, Samantha J.,Mevers, Emily
, p. 1043 - 1055 (2022/01/20)
Luquilloamides A–G (1–7) were isolated from a small environmental collection of a marine cyanobacterium found growing on eelgrass (Zostera sp.) near Luquillo, Puerto Rico. Structure elucidation of the luquilloamides was accomplished via detailed NMR and MS analyses, and absolute configurations were determined using a combination of advanced Mosher’s method, J-based configuration analysis, semisynthetic fragment analysis derived from ozonolysis, methylation, Baeyer–Villiger oxidation, Mosher’s esterification, specific rotations, and ECD data. Except for 2, the luquilloamides share a characteristic tert-butyl-containing polyketide fragment, β-alanine, and a proposed highly modified polyketide extension. While compound 1 is a linear lipopeptide with two α-methyl branches and a vinyl chloride functionality in the polyketide portion, compounds 4, 6, and 7 possess a cyclohexanone structure with methylation on the α- or β-positions of the polyketide as well as an acetyl group. Interestingly, the absolute configuration at C-5 and C-6 on the cyclohexanone unit in 7 is opposite to that of 4–6. Compound 3 was revealed to have a tert-butyl-containing polyketide, β-alanine, and a PKS/NRPS-derived γ-isopropyl pyrrolinone. Compound 2 may be a hydrolysis product of 3. Of the seven new compounds, 1 showed the most potent cytotoxicity to human H-460 lung cancer cells.
Branched-Chain Carbohydrate Lactones from a Samarium(II) Iodide-Promoted Serial Deoxygenation-Carbonyl Addition Reaction
Enholm, Eric J.,Jiang, Shujun,Abboud, Khalil
, p. 4061 - 4069 (2007/10/02)
A new deoxygenation-carbonyl addition reaction mediated by samarium(II) iodide (SmI2) in THF/HMPA was examined with carbohydrate lactones and several substrates containing an α-alkoxy carboxylic ester.In a single reaction, these compounds were deoxygenate
Substitution of 2-(Sulfonyloxy)carboxylates with Oxygene and Sulfur Nucleophiles without Racemization
Burkard, Ulrike,Effenberger, Franz
, p. 1594 - 1612 (2016/06/15)
The ethyl 2-(sulfonyloxy)propionates (S)-1a-c react with phenolates formed from 2 and with carboxylates 8 to give the respective 2-(aryloxy)- (R)-3 and 2-(acyloxy)propionates (R)-9 with inversion of configuration.Due to the high leaving tendency of the triflate group, (S)-1a generally give higher yields of substitution products under milder conditions than the corresponding mesylate (S)-1b and tosylate (S)-1c.In the case of the reaction of malic and succinic acid derivatives only the triflate (S)-10a is converted to the acyloxy compounds (R)-12 with carboxylates 8 atlow temperature (-45 deg C); with the mesylates 10b and the bromide 10d only elimination is observed.Mercaptides and thiophenolates formed from 17 react with (S)-1a-c analogously.With potassium thiocyanate 1a,b react almost exclusively to give the thiocyanate 19; only traces of the corresponding isothiocyanate 20 are obtained.
