Um protocolo livre de metais foi desenvolvido para sintetizar indanos através da contração de anel de 1,2-di-hidronaftalenos promovida por PhI(OH)OTs (HTIB ou reagente de Koser). Este rearranjo oxidativo pode ser realizado em diversos solventes (MeOH, CH 3 CN, 2,2,2-trifluoroetanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), e uma mistura 1:4 de TFE:CH 2 Cl 2 ) em condições brandas. A contração de anel fornece indanos trans-1,3-dissubstituídos diastereosseletivamente, os quais são difíceis de obter em química orgânica sintética.A metal-free protocol was developed to synthesize indanes by ring contraction of 1,2-dihydronaphthalenes promoted by PhI(OH)OTs (HTIB or Koser's reagent). This oxidative rearrangement can be performed in several solvents (MeOH, CH 3 CN, 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and a 1:4 mixture of TFE:CH 2 Cl 2 ) under mild conditions. The ring contraction diastereoselectively gives functionalized trans-1,3-disubstituted indanes, which are difficult to obtain in synthetic organic chemistry.Keywords: indanes, hypervalent iodine, ring contraction, 1,2-dihydronaphthalenes, rearrangements IntroductionThe indane ring system is present in several natural products and in non-natural compounds with remarkable biological activity.1 Consequently, efforts have continuously been made to develop new routes to obtain molecules with this unit.2 A typical strategy to synthesize a functionalized indane is by selecting an appropriate indanone, which is then elaborated into the target molecule. 2,3 As tetralones are usually cheaper than indanones, the preparation of indanes starting from a tetralone (or a derivative) through a ring contraction rearrangement could be advantageous. 4 In the last years, hypervalent iodine reagents have become an essential tool in synthetic organic chemistry due to the plethora of reactions that can be performed with them in excellent yield and selectivities. 5 Moreover, hypervalent iodine compounds represent in many cases an alternative to toxic heavy metals. 5 Although the oxidative rearrangement of alkenes mediated by iodine(III) has been described in some papers, 6 the ring contraction of 1,2-dihydronaphthalenes was reported for a few substrates using only p-Me-C 6 H 4 -IF 2 , 6 which led to fluorinated indanes.Herein, we describe an efficient metal-free protocol for the synthesis of indanes under mild conditions. In a preliminary communication, we report the ring contraction of 1,2-dihydronaphthalenes (which are obtained from 1-tetralones) mediated by PhI(OH)OTs (HTIB or Koser's reagent) for a few substrates. 7 In this article, the oxidation of several additional substrates is presented, better defining the reaction scope. Additionally, other reaction conditions were Metal-Free Synthesis of Indanes by Iodine(III)-Mediated Ring Contraction J. Braz. Chem. Soc. 1796 discovered using fluoroalcohols as solvent, which highly improved isolated yields. The best condition employed a 4:1 mixture of CH 2 Cl 2 -TFE that led to indanes in...

[reaction: see text] A new approach for the synthesis of (+/-)-indatraline, which is a 3-phenyl-1-indanamine that displays several biological activities, is described. The strategy features as the key step a diastereoselective ring contraction of a 1,2-dihydronaphthalene promoted by PhI(OTs)OH, to construct the indan ring system. The oxidative rearrangement of other 1,2-dihydronaphthalenes was also investigated, generalizing this method to obtain indans.

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A new approach for the synthesis of indatraline was developed using as the key step an iodine(III)-mediated ring contraction of a 1,2-dihydronaphthalene derivative. Behavioral tests were conducted to evaluate the effect of indatraline and of its precursor indanamide on the motor activity of Wistar rats. Specific indexes for ambulation, raising and stereotypy were computed one, two and three hours after i.p. drug administration. Indatraline effects on motor activity lasted for at least three hours. On the other hand, no significant differences in motor activity were observed using indanamide. The results suggest that indatraline has a long lasting effect on motor activity and add evidence in favor of the potential use of that compound as a substitute in cocaine addiction.