Results 51 to 60 of about 6,084 (222)

Tricarbocyclic core formation of tyrosine-decahydrofluorenes implies a three-enzyme cascade with XenF-mediated sigmatropic rearrangement as a prerequisite

Acta Pharmaceutica Sinica B, 2021
Tyrosine-decahydrofluorene derivatives feature a fused [6.5.6] tricarbocyclic core and a 13-membered para-cyclophane ether. Herein, we identified new xenoacremones A, B, and C (1−3) from the fungal strain Xenoacremonium sinensis ML-31 and elucidated ...
Zhiguo Liu, Wei Li, Peng Zhang, Jie Fan, Fangbo Zhang, Caixia Wang, Shuming Li, Yi Sun, Shilin Chen, Wenbing Yin   +9 more
doaj  

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene [PDF]

, 2015
1,4-Diols resulting from the double addition of ArCCLi (Ar = Ph, substituted phenyl, 2-thienyl) to ortho-C6H4(CHO)2 undergo cascades to tetracenes on simple admixture of LiHDMS, CS2 and MeI.
Burroughs, Laurence, Khan, Dilfaraz, Lewis, William, Ngwenya, Mkhethwa, Ritchie, John, Woodward, Simon   +5 more
core   +3 more sources

Indole Synthesis via Allenyl Ester; Enantioselective Total Synthesis of Geissoschizoline

ChemistryEurope, EarlyView.
An indole synthesis via an allenyl ester intermediate at ambient temperature has been developed. The mild reaction conditions allow the use of a broad range of substrates. Notably, the utility of this approach is demonstrated through the asymmetric total synthesis of geissoschizoline, a Strychnos‐type monoterpenoid indole alkaloid.
Sohsuke Moriue, Honami Nishioka, Yuto Fukuda, Hiromitsu Takayama, Mariko Kitajima, Hayato Ishikawa   +5 more
wiley   +1 more source

Regio- and stereoselectivity in the Lewis acid- and NaH-induced reactions of thiocamphor with (R)-2-vinyloxirane [PDF]

, 2006
The reaction of the enolizable thioketone (1R,4R)-thiocamphor (=(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptane-2-thione; 1) with (R)-2-vinyloxirane (2) in the presence of a Lewis acid such as SnCl4 or SiO2 in anhydrous CH2Cl2 gave the spirocyclic 1,3 ...
Fedorov, A, Fu, C, Heimgartner, H
core   +1 more source

The [3,3]‐Sigmatropic Allyl Cyanate–Isocyanate Rearrangement on Levoglucosenone Derivatives Stereoselectively Provides 4‐Deoxy‐4‐Aminosugars

Chemistry–Methods, EarlyView.
The Ichikawa rearrangement of allyl cyanates obtained in situ from levoglucosenone‐derived allyl carbamates allows the synthesis of unique 4‐deoxy‐4‐amino‐d‐allose derivatives with complete chirality transfer in a metal‐free three‐step, one‐pot manner.
Debora Pratesi, Marta Rigacci, Beatriz Pava‐Gómez, Camilla Matassini, Andrea Goti, Cristina Faggi, Francesca Cardona   +6 more
wiley   +1 more source

Structure of 3,4-Dihydroxy-2-butanone 4-Phosphate Synthase from Methanococcus jannaschii in Complex with Divalent Metal Ions and the Substrate Ribulose 5-Phosphate: implications for the catalytic mechanism [PDF]

, 2003
Skeletal rearrangements of carbohydrates are crucial for many biosynthetic pathways. In riboflavin biosynthesis ribulose 5-phosphate is converted into 3,4-dihydroxy-2-butanone 4-phosphate while its C4 atom is released as formate in a sequence of metal ...
Bacher, Adelbert, Fischer, Markus, Huber, Robert, Richter, Gerald, Schiffmann, Susanne, Steinbacher, Stefan   +5 more
core  

A Base‐Mediated Rearrangement of the Benzylic 1,5‐Hexadipyridynyl Moiety

ChemPlusChem, Accepted Article.
We report a previously unrecognized base‐mediated rearrangement of a benzylic 1,5‐hexadipyridynyl moiety. Upon exposure to base, we show this structural motif to rearrange into a constrained vinyl‐pyridine substituted cyclobutene. Computational modeling indicates that the rearrangement takes place following a route involving stepwise deprotonation ...
Wouter A. Remmerswaal, Thai-Tony Nguyen, Han Zijan, Fedor Krasovski Slobodian, Ruisheng Xiong, Vadim Kessler, Zhijian Xu, Weiliang Zhu, Mate Erdelyi   +8 more
wiley   +1 more source

Microwave-assisted generation and reactivity of aza- and diazafulvenium methides: heterocycles via pericyclic reactions [PDF]

, 2008
Azafulvenium methides and diazafulvenium methides have been generated under microwave irradiation from 2,2-dioxo-1H,3H-pyrrolo[1,2-c]thiazoles and 2,2-dioxo-1H,3H-pyrazolo[1,5-c]thiazoles, respectively.
Melo, Teresa M. V. D. Pinho e, Soares, Maria I. L.   +1 more
core   +1 more source

Reaction of Nitrones with Phosphinylallenes: DFT Mechanistic Investigations

European Journal of Organic Chemistry, EarlyView.
The mechanism of the reaction between phosphinylallenes and nitrones is investigated by DFT calculations to elucidate the overall pathway and the stereochemical outcome. The initial (3+2) cycloaddition delivers an unstable isoxazolidine ylidene intermediate, spontaneously rearranging to the 4‐phosphinylpyrrolidin‐3‐one via a radical pathway. This study
Rayhane Hammami, Pascale Maldivi, Sébastien Carret, Soufiane Touil, Jean‐François Poisson, Benjamin Darses   +5 more
wiley   +1 more source

Stereoselective Synthesis of (-)-Spicigerolide [PDF]

, 2013
(-)-Spicigerolide was enantioselectively synthesized from a protected (S)-lactaldehyde. The synthesis of the polyacetylated framework relied on two Zn-mediated stereoselective additions of alkynes to aldehydes as well as a regiocontrolled [3,3 ...
Achmad S., Alemany A., Amador M., Anand N. K., Ariza X., Birch A. J., Boalino D. M., Boucard V., Boyal D., Boyer J., Collet L. A., Connon S. J., Davies-Coleman M. T., Davis-Coleman M. T., Diez R. S., Díaz-Oltra S., El-Sayed E., Falomir E., Falomir E., Frantz D. E., Fürstner A., Gao D., Gao D., García-Fortanet J., García-Fortanet J., Hafner A., Hoveyda A. H., Kojima N., Lichtenthaler F. W., Lichtenthaler F. W., Marco J. A., Murga J., Pereda-Miranda R., Pereda-Miranda R., Ramachandran P. V., Saito S., Trnka T., Trost B. M., Valverde S.   +38 more
core   +2 more sources