Rearrangement of beta,gamma-unsaturated esters with thallium trinitrate: synthesis of indans bearing a beta-keto ester moiety

Silva, Luiz F.; Pedrozo, Eliane C.; Ferraz, Helena M. C.

doi:10.1590/s0103-50532006000100029

Cited by 7 publications

(6 citation statements)

References 8 publications

(18 reference statements)

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“…Using only 1.1 equivalents of TTN, the reaction time needed to consume all the starting material 10 increased and gave more byproducts. 11,14 In addition, under such conditions, the isolated product was exclusively 13, in 45% yield. The reactivity of 11 toward thallium(III) was similar to that of 10.…”

Section: Methodsmentioning

confidence: 93%

“…10 Considering that only the reactivity of homoallylic alcohols bearing electrondonating groups was investigated (see Scheme 1), 4 we decided to extend the reactions of primary homoallylic alcohols with TTN to substrates containing electronwithdrawing groups, as previously performed for the reaction of 1,2-dihydronaphthalenes. 10,11 Thus, the bromo derivatives 10 and 11 were synthesized in four steps. 4,11,12 The reaction of 10 with TTN was performed under several conditions, varying solvent (AcOH-H 2 O or AcOH), amount of TTN and reaction time.…”

Section: Methodsmentioning

confidence: 99%

“…10,11 Thus, the bromo derivatives 10 and 11 were synthesized in four steps. 4,11,12 The reaction of 10 with TTN was performed under several conditions, varying solvent (AcOH-H 2 O or AcOH), amount of TTN and reaction time. The best yield for the desired ring contraction product 12 was obtained using two equivalents of TTN and acetic acid as solvent ( Table 1, entry 1).…”

Section: Methodsmentioning

confidence: 99%

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Rearrangement of Homoallylic Alcohols with Thallium(III): Diastereoselective Synthesis of Indans Bearing a β-Hydroxy Ketone Moiety

Silva¹,

Quintiliano²,

Craveiro³

et al. 2007

Synthesis

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Several aspects of the synthesis of indans through a thallium(III)-mediated ring contraction reaction of 1,2-dihydronaphthalene derivatives bearing suitably positioned primary and secondary hydroxyl groups are disclosed. The relative configuration of 3-(2,3-dihydro-1H-inden-3-yl)-2-methyl-3-oxopropyl 4-bromobenzoate was assigned by X-ray crystal structure analysis, allowing additional insights into the mechanism of the thallium(III)-promoted oxidative rearrangement of homoallylic alcohols. The reaction of primary homoallylic alcohols bearing the electron-withdrawing group bromine gave indans in 52-55% yield using an excess of thallium trinitrate (TTN). Furthermore, the thallium(III)-mediated oxidative rearrangement of the secondary homoallylic alcohols gave, in a diastereoselective fashion, indans bearing up to three stereocenters.The ring contraction of substrates containing a six-membered ring is an efficient approach to the preparation of cyclopentane derivatives, because the reorganization of the bonds during the rearrangement usually occurs with a high level of selectivity. 1 Thus, ring contraction reactions constitute a powerful tool in the total synthesis of complex molecules. 2 One of the reagents that can induce ring contraction of cycloalkenes and cycloalkanones in an efficient manner is TTN. 3 Such a reagent can promote, for instance, the oxidative rearrangement of 1,2-dihydronaphthalenes containing a suitably positioned hydroxyl group, to afford indans. 4 Moreover, this rearrangement occurs in a diastereoselective manner, giving a single diastereomer as product, whose relative configuration has not been determined (Scheme 1). To explain this selectivity, a coordination between the thallium(III) atom and the hydroxyl group of the side-chain has been proposed. Likewise, similar tertiary homoallylic alcohols without vicinal substituents afford indans in good yields. 5In contrast to the behavior of the primary and tertiary homoallylic alcohols cited above, the reaction with TTN of tertiary homoallylic alcohols bearing a vicinal methyl group gave only fragmentation products (Scheme 2). 5 The lack of ring contraction in this case can be explained by the steric effect of the additional methyl group, which would preclude the formation of the oxythallated intermediate.Although several aspects of the thallium(III)-mediated oxidation of dihydronaphthalene derivatives bearing homoallylic hydroxyl groups have already been described, several questions remain unanswered. Herein, we report a detailed study of this kind of thallium(III)-promoted oxidation, describing: (i) the assignment of the relative configuration of indans, such as 2; (ii) the influence of the electron-withdrawing group bromine on the rearrangement of homoallylic alcohols, such as 1; and (iii) the ring contraction of secondary homoallylic alcohols, which leads to diastereomeric pure indans with up to three stereocenters.The indan 2a bears stereocenters at the cyclopentanic ring and at the side-chain. This unusual pattern makes the determination of ...

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Section: Methodsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Rearrangement of Homoallylic Alcohols with Thallium(III): Diastereoselective Synthesis of Indans Bearing a β-Hydroxy Ketone Moiety

Silva¹,

Quintiliano²,

Craveiro³

et al. 2007

Synthesis

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“…In a recent example, the thallium trinitrate (TTN)‐mediated oxidative rearrangement of β,γ‐unsaturated esters 161 to give indane derivatives 162 was described. The proposed mechanism begins with the oxythallation of the double bond, favored by the coordination of the oxygen of the ester group; this is followed by carbonyl formation, with simultaneous ring contraction, ensuing from migration of the aromatic ring to the carbon bonded to thallium (Scheme ) . A similar kind of transformation, with PhI(OH)(OTs) (Koser's reagent) as a promoter, allowed the diastereoselective synthesis of trans ‐1,3‐disubstituted indanes in a 4:1 mixture of TFE/CH 2 Cl 2 under mild conditions in a metal‐free procedure …”

Section: Synthesis Of Indanesmentioning

confidence: 99%

“… Synthesis of indane derivatives 162 by thallium trinitrate (TTN)‐mediated oxidative rearrangement of β,γ‐unsaturated esters 161 …”

Section: Synthesis Of Indanesmentioning

confidence: 99%

Recent Advances in the Synthesis of Indanes and Indenes

Gabriele

Mancuso

Veltri

2016

Chemistry A European J

168

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Indanes and indenes are among the most important carbocycles. Many indane and indene derivatives have shown important pharmacological activities, and the indane and indene nuclei are structural motifs present in several natural products of biological relevance. In spite of their importance, only a few reviews on their preparation methods have appeared so far in the literature, the most recent ones being published about ten years ago. The present Review is aimed at filling this gap, presenting some of the most important and innovative approaches to indanes and indenes that have been published in the course of the last ten years (coverage: from 2005 to May, 2015).

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