Producción Científica Profesorado

The stereochemistry of the 1,3-dipolar cycloadditions of diazomethane to pseudoguaianolides



Alvarado Rodríguez, José Guadalupe

2017

Adriana Ortiz-León, J. Martín Torres-Valencia, J. Jesús Manríquez-Torres, José G. Alvarado-Rodríguez, Carlos M. Cerda-García-Rojas, Pedro Joseph-Nathan, Tetrahedron: Asymmetry, 2017, 28 (2), 367?373https://doi.org/10.1016/j.tetasy.2017.01.009


Abstract


The 1,3-dipolar cycloaddition of diazomethane to the sesquiterpene lactones, parthenin, coronopilin, and psilostachyin, gave their respective spiropyrazolines with complete chemoselectivity, while the diastereoselectivity in favour of the (11S)-stereoisomer was 86?98%. Similarly, mexicanin I acetate, helenalin, and helenalin acetate provided the (11R)-diastereoisomer. When helenalin and its acetate were treated with a large excess of diazomethane, they afforded their respective dipyrazolines with 98% diastereoselectivity in favour of the (2R,3S,11R)-diastereoisomer. All compounds were characterized by their physical and spectroscopic properties and their absolute configuration was established by X-ray diffraction analysis calculating the Flack and Hooft parameters.



Producto de Investigación




Artículos relacionados

Synthesis, characterization and crystal structures of dipyridyl-N-methylimine and cloro-bis (N,N?-2,...

Synthesis and Spectroelectrochemical Studies of Mixed Heteroleptic Chelate Complexes of Ruthenium(II...

Synthesis, characterization and crystal structures of organolead dithiolate compounds displaying tra...

Hypervalence in germanium compounds containing the tetracylic moiety {S(C6H3S)2O}Ge via OGe transann...

Synthesis, characterization, and crystal structures of n-alkyldiorganodithiophosphates RS2P(OC6H4)2

Complexation of the uranyl ion (UO2)2+ with a tetraphenylimidodiphosphinate ligand: the first trinuc...

Synthesis and crystal structures of cis-palladium(II) and cis-platinum(II) complexes containing dipy...

Five-membered ring chelate complexes of Ni(II), Pd(II) and Pt(II) derived of di-(2-pyridyl)-N-ethyli...

Mild Oxidation of C?C Bonds of Benzoiridacycles

Ni(II) and Pd(II) organometallic and coordination complexes with a new tridentate N,N,O-donor ligand...