Synthesis and Reactivity of η<sup>4</sup>-Diene-Fe(CO)<sub>3</sub> Complexes from <i>exo</i>-2-Oxazolidinone Dienes. A Facile Generation of Stable Conjugated Enol-Enamido Species
作者:Fernando Ortega-Jiménez、Adriana Benavides、Francisco Delgado、Hugo A. Jiménez-Vázquez、Joaquín Tamariz
DOI:10.1021/om900772z
日期:2010.1.11
A synthesis of new η4-diene-Fe(CO)3 complexes derived from the novel exo-2-oxazolidinone dienes is described. These complexes were prepared by thermal complexation of the substituted dienes with diiron nonacarbonyl to afford the corresponding complexes as crystal solids. The X-ray single-crystal structure analysis revealed characteristic structural properties for diene-iron complexes, showing that
Hernandez, Raul; Sanchez, Jose M.; Gomez, Adriana, Heterocycles, 1993, vol. 36, # 9, p. 1951 - 1956
作者:Hernandez, Raul、Sanchez, Jose M.、Gomez, Adriana、Trujillo, Gonzalo、Aboytes, Rossana、et al.
DOI:——
日期:——
One-Step Synthesis and Highly Regio- and Stereoselective Diels−Alder Cycloadditions of Novel <i>exo</i>-2-Oxazolidinone Dienes
作者:Ashis B. Mandal、Adriana Gómez、Gonzalo Trujillo、Francisco Méndez、Hugo A. Jiménez、María de Jesús Rosales、Rafael Martínez、Francisco Delgado、Joaquín Tamariz
DOI:10.1021/jo962403g
日期:1997.6.13
An improved synthesis of exo-heterocyclic dienes like N-substituted 4,5-dimethylene 2-oxazolidinones 1, by a one-step method from diacetyl and isocyanates, was described. This highly convergent synthetic strategy has been successfully used for the preparation of novel (Z)-5-ethylidene-4-methylene analogs 4 in fair yields. Both dienes 1 and 4 undergo efficient addition of symmetric dienophiles in thermal Diels-Alder reactions, inasmuch as they react stereo- and regioselectively with the unsymmetric olefins methyl vinyl ketone (MVK) and methyl propiolate. This regioselectivity was greatly improved by using Lewis acid catalysts (TiCl4, AlCl3). The nitrogen atom of the 2-oxazolidinone ring seems to control the orientation of the dienophile approach. These results have been rationalized in terms of the frontier molecular orbital theory by ab initio calculations. For dienes 4, addition of MVK gave the endo isomer as the major product. Dimerization of dienes 4 was also highly regio-, chemo-, and stereoselective, giving only isomer 17. This reaction furnished a second product, which corresponded to dienes 18 obtained by the [1,5] sigmatropic rearrangement of 4. The structure of the dienes and main products was established by NMR experiments and X-ray diffraction analysis.
Synthesis and Cycloaddition Reactions of New Captodative Olefins, N-Substituted 5-Alkylidene-1,3-oxazolidine-2,4-diones
作者:Joaquín Tamariz、Adriana Benavides、Rafael Martínez、Hugo A. Jiménez-Vázquez、Francisco Delgado、Joaquin Tamariz
DOI:10.3987/com-00-9094
日期:——
Total Synthesis of the Natural Carbazoles Glycozolicine, Mukoline, and Mukolidine, Starting from 4,5-Dimethyleneoxazolidin-2-ones
A novel and efficient synthesis of naturally occurring 1-methoxycarbazoles glycozolicine, mukolidine, and mukoline is developed by applying a regioselective Diels-Alder reaction of a 4,5-dimethyleneoxazolidin-2-one with acrolein. The cycloadduct is transformed to the corresponding functionalized diarylamine. The key palladium-catalyzed cyclization/deformylation cascade reaction of the latter leads to glycozolicine in high overall yield. Oxidation of the C6 methyl group provides the 6-formylcarbazole mukolidine, which is reduced to the respective natural alcohol mukoline.