226079-85-2Relevant academic research and scientific papers
Syntheses of Gymnothespirolignans B and C and Non-natural Isomer 9-Epi-gymnothespirolignan B
Ali, Ghada,Cuny, Gregory D.
supporting information, 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.
supporting information, 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
supporting information, 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 0086-0087, (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
Highly stereo- and regioselective synthesis of (Z)-trisubstituted alkenes via 1-bromo-1-alkyne hydroboration-migratory insertion-Zn-promoted iodinolysis and Pd-catalyzed organozinc cross-coupling
Huang, Zhihong,Negishi, Ei-Ichi
, p. 14788 - 14792 (2008/09/17)
Hydroboration of 1-bromo-1-alkynes with dibromoborane followed by addition of 3 or 4 equiv of Me2Zn provides an efficient and selective route to (Z)-2-alkenyldimethylboranes (3) or (Z)-2-alkenylmethylzincs (4), respectively, which have been suc
A convergent total synthesis of pumiliotoxins A and B via palladium-catalyzed cross-coupling reaction of homoallylic organozinc compounds with vinyl iodides
Kibayashi, Chihiro,Aoyagi, Sakae
, p. 229 - 233 (2007/10/03)
A versatile convergent approach for preparing the pumiliotoxin alkaloids has been developed employing a Pd(0)-catalyzed cross-coupling reaction between homoallylic organozincs and vinyl iodides, which led to the asymmetric total synthesis of (+)-pumilioto
Synthetic studies of the 18-membered antitumor macrolide, tedanolide. 3. Stereocontrolled synthesis of the C1-C12 part via a synthesis of the C1-C7 fragment by a mismatched but efficient sharpless dihydroxylation and its coupling with the C8-C11 fragment
Matsushima, Tomohiro,Mori, Michiko,Zheng, Bao-Zhong,Maeda, Hiroshi,Nakajima, Noriyuki,Uenishi, Jun-Ichi,Yonemitsu, Osamu
, p. 308 - 321 (2007/10/03)
The C1-C12 part (4) of tedanolide (1) was synthesized starting from methyl (R)-3-hydroxy-2-methylpropionate (11a) via a coupling between the C1- C7 aldehyde (6) and the C8-C11 iodoalkene (7a). For a synthesis of 6, a mismatched but highly efficient Sharpless dihydroxylation of the α,β- unsaturated ester (15) with AD-mix-α was successfully applied. Compound 7a was synthesized using hydrozirconation to the alkyne (32).
