337375-93-6Relevant academic research and scientific papers
Syntheses of Gymnothespirolignans B and C and Non-natural Isomer 9-Epi-gymnothespirolignan B
Ali, Ghada,Cuny, Gregory D.
, p. 10517 - 10525 (2021/07/31)
Syntheses of polycyclic spiro lignans gymnothespirolignans B and C as well as the unnatural isomer 9-epi-gymnothespirolignan B were accomplished using (R)-Roche ester and an appropriately substituted fluorenone. Key features of the convergent syntheses include coupling of the fluorenone and an iodo-alkene intermediate derived from (R)-Roche ester in the presence of the Lewis acid TiCl(OiPr)3, C9-O bond formation via an SN2 reaction with retention of stereochemistry, and diastereoselective hydrogenations of a common alkene intermediate guided by accessibility or positioning by the C8-methoxy.
Stereospecific Allylic Functionalization: The Reactions of Allylboronate Complexes with Electrophiles
García-Ruiz, Cristina,Chen, Jack L.-Y.,Sandford, Christopher,Feeney, Kathryn,Lorenzo, Paula,Berionni, Guillaume,Mayr, Herbert,Aggarwal, Varinder K.
, p. 15324 - 15327 (2017/11/06)
Allylboronic esters react readily with carbonyls and imines (π-electrophiles), but are unreactive toward a range of other electrophiles. By addition of an aryllithium, the corresponding allylboronate complexes display enhanced nucleophilicity, enabling addition to a range of electrophiles (tropylium, benzodithiolylium, activated pyridines, Eschenmoser's salt, Togni's reagent, Selectfluor, diisopropyl azodicarboxylate (DIAD), MeSX) in high regio- and stereocontrol. This protocol provides access to key new functionalities, including quaternary stereogenic centers bearing moieties such as fluorine and the trifluoromethyl group. The allylboronate complexes were determined to be 7 to 10 orders of magnitude more reactive than the parent boronic ester.
Quinocidin, acytotoxic antibiotic with anunusual 3,4-dihydroquinolizinium ring and michael acceptor reactivity toward thiols
Nakagawa, Yu,Sawaki, Yuki,Kimura, Takahiro,Tomura, Tomohiko,Igarashi, Yasuhiro,Ojika, Makoto
, p. 17894 - 17897 (2019/03/07)
Cytotoxicity-guided fractionation of the culture broth of Actinomadura sp. TP-A0019 led to the isolation of quinocidin (1), acytotoxic antibiotic with an unusual 3,4-dihydroquinolizinium ring. The structural assignment was made on the basis of high-field NMR experiments and chemical synthesis. Comparison ofthe spectral properties of 1 with those of its synthetic counterparts revealed that 1 is aracemic mixture of two enantiomers, which showed similar cytotoxicity against HeLa-S3 cells. Nucleophile-trap-ping experiments demonstrated that 1 captured 2-mer-captoethanol and N-acetyl-l-cysteine by means of aMi-chael addition-type reaction, but was inert toward 2-ami-noethanol and glycolic acid. Notably, the addition of 1 to thiols proceeded smoothly in neutral aqueous media at room temperature. In view of the thiol-trapping ability and the unusual structure, 1 provides aunique scaffold for designing drug leads and protein-labeling probes.
PROCESS FOR PREPARATION OF (3R)-2,4-DI-LEAVING GROUP-3-METHYLBUT-1-ENE
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Paragraph 0070-0071, (2013/06/27)
The specification relates to compounds and process for the preparation of a compound of formula 7, where LG is a leaving group and hal is a halide and is Cl, Br or I. The compound of formula 7 can be useful in the preparation of natural products, such as
Ru-catalyzed alkene-alkyne coupling. Total synthesis of amphidinolide P
Trost, Barry M.,Papillon, Julien P. N.,Nussbaumer, Thomas
, p. 17921 - 17937 (2007/10/03)
A coordinatively unsaturated ruthenium complex catalyzed the formation of a carbon-carbon bond between two judiciously chosen alkene and alkyne partners in good yield, and in a chemo- and regioselective fashion, despite the significant degree of unsaturation of the substrates. The resulting 1,4-diene forms the backbone of the cytotoxic marine natural product amphidinolide P. The alkene partner was rapidly assembled from (R)-glycidyl tosylate, which served as a linchpin in a one-flask, sequential three-components coupling process using vinyllithium and a vinyl cyanocuprate. The synthesis of the alkyne partner made use of an unusual anti-selective addition under chelation-control conditions of an allyltin reagent derived from tiglic acid. In addition, a remarkably E-selective E2 process using the azodicarboxylate-triphenylphosphine system is featured. Also featured is the first example of the use of a β-lactone as a thermodynamic spring to effect macrolactonization. The oxetanone ring was thus used as a productive protecting group that increased the overall efficiency of this total synthesis. This work was also an opportunity to further probe the scope of the ruthenium-catalyzed alkene-alkyne coupling, in particular using enynes, and studies using various functionalized substrates are described.
Alkene-alkyne coupling as a linchpin: An efficient and convergent synthesis of amphidinolide P
Trost, Barry M.,Papillon, Julien P. N.
, p. 13618 - 13619 (2007/10/03)
A short and efficient synthesis of the cytotoxic macrolide amphidinolide P is described. A remarkably chemo- and regioselective ruthenium-catalyzed alkene-alkyne coupling allows for a convergent synthesis and demonstrates that both enynes and β-lactones are suitable coupling partners. This work also features a novel strategy for the preparation of macrolactones via intramolecular transesterification of β-lactones. The target structure was prepared in 15 steps for the longest linear sequence and 10% overall yield, 24 steps total. Copyright
