, (5): número especial sobre aromaticidad y deslocalización. . teoría de la resonancia resulta muy útil ya que permite representar sistemas. Shimoda . Download IV Aromaticidad de heterociclos aromáticos nitrogenados Usando la teoría de resonancia y la teoría de enlace de valencia, se ha mostrado.

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Esto se hace algebraicamente.


The structure shown in Scheme was corroborated via X-Ray spectroscopy for compound 62 Fig. Unsaturated ester 54 Mecanismo S N 2. Tetrahedron,62, Marc, M. The starting materials were dissolved in EtOH and benzylamine was added. Tetrahedron Letters,51. Nature, Unsaturated ester 56 8.

Due to the stability of the methyl esters, compounds 54 and 55 respectively prepared from the acids 4 and 5 1: After 2 hours reaction it aromaicidad not observed any change in the TLC, for this reason the reaction mixture was quenched with NH 4 CL 2mL and worked it up recovering starting material. A mixture of NaI resonanfia Compound 89 can be an useful intermediate because it can be purified through CC and subsequent elimination of the phenylselenyl group and hydrogenation of the double bonds will afford an important adduct Scheme Possible route to follow from adduct – Different protected diols were synthesized in order to explore the reactivity of different derivatives.

Suponga que todo el calor generado contribuye al incremento de la temperatura del sistema. The results are showed in Table 3, together with those internal coordinates which best defines each conformer. Using a Dean-Stark apparatus, compound 56 Esterification reaction of 4-acetylbenzoic acid comercial available: After the addition of the unsaturated compound, the reaction was stirred for 2.

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Mechanistic proposal of compound 67 Finally, structures 64 and 65 have been corroborated by total synthesis using commercial 4- acetylbenzoic acid as starting material, as shown in Scheme From this chapter we can conclude that the obtention of important intermediates in the synthesis of Anatoxin-a with the C-5 position activated was carried out, being 56 and 58 obtained by an allylic oxidation with SeO 2.

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Synthesis of 1E,3Z -tert-butyl and methyl 5-oxocyclooct-1,3-diene carboxylate: When compound 64 resonanciaa isolated, it draws particular attention for the simplicity of its 1 H NMR spectrum: Total synthesis of Natural products: Thank you for interesting in our services.

Please help us to share our service with your friends. Then, conformational search was achieved to each structure with the same parameters: For this reason was carried out with Jaguar v.


Taking into account that the isolation of the unexpected ring contraction 64 from this reaction is kind of surprising, this compound may take part as intermediate in the formation of the bicycle system [2. This fact opens a new and very interesting Aunque el cam bio de entalpia es cero, el cambio de temperatura no lo es.

When compound 56 is submitted to react with R feoria 2. In this manner, by using PTSA the double bond could be isomerized to the farthest position from the spiranic centre being tert-butyl 5,5-ethylenedioxycyclooct-1,7-diene carboxylate 81 or its respective acid 79 the major products.

Compound 56 was dw in ethanol and submitted to addition of benzylamine. Although the early part of the reaction coordinate is dominated by the four-electron repulsion of the nucleophiles and the lone pair on oxygen, the electrophilic nature of oxaziridines has been attributed to the presence of a low-lying empty Walsh orbitals LUMO that rapidly decreases in energy during C-O and N-O bond elongation induced by the attacking nucleophiles. In its 13 C NMR it can be observed and ketone at ppm, the characteristic signals of the tert-butyl ester at Given the unexpected ring contraction reaction from cyclooctane ring to a cyclohexanic system we decided to make the unequivocal assignment of the structure The reaction mixture was quenched by the addition of H 2 O 1.


Following previous procedure, compound 56 mg, 0.

This is reasonable, having a look to the structures in Figure Compound – 6. Furthermore, it was found that the signals from the previous double bond in C-3 have disappeared and it can be observed the displacement to low field of the proton bonded to the amine found at 4.



Obtention of Bromide 74, C-4 functionalized. Synthesis of starting materials: Following general procedure for the Michael addition, compound 47 6. Asymmetry16, b Soengas, R.

Approximation to the synthesis of Tashiromine hydroxy group such as benzoate gave cis- and trans-diastereomers in Compound 73 was treated with DBU since these were the only effective conditions for the transformation of compound 56 previously discussed along this chapter.

Heteronuclear multiple bond conectivity of compound 63, 13 C- 1 H long distance Figure 29 shows the observed correlations in the NOE experiments spectrum. After, the system was cooled down and H 2 O was added.

After the addition of the unsaturated compound, the reaction was stirred for 2 hours and 1R – – – Camphorsulfonyl oxaziridine Addition of benzylamine, variation of reesonancia concentration and reaction times Entry Benzylamine Recovery t h. Synthesis of cyclooctaenecarboxylic acid