Thallium in organic synthesis. 43. Novel oxidative rearrangements with thallium(III) nitrate (TTN) in trimethyl orthoformate (TMOF)

Taylor, Edward C.; Robey, Roger L.; Liu, K. T.; Favre, B.; Bozimo, H. T.; Conley, Richard A.; Chiang, Chih-Shu; McKillop, Alexander; Ford, Michael E.

doi:10.1021/ja00426a072

Cited by 53 publications

(9 citation statements)

References 2 publications

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“…102 "C/4 Torr; 79% isolated yield; 6, 1.70 (d, 3 H), 5.30 (q, 1 H), and 7. 4 Rearrangement Procedure.-A typical experimental procedure is as follows (reaction conditions and product yields are shown in Table 1). A mixture of 2-bromo-4'-isobutylpropiophenone (1; R = Bu', X = Br) (13.0 g, 50 mmol), TTN (22.2 g, 50 mmol), 70% perchloric acid (9.3 ml, 100 mmol), and TMOF (550 ml) was stirred at 25 "C for 25 h. About three-quarters of the TMOF was then distilled off under reduced pressure and the residue was treated with CHCI, (200 ml).…”

Section: Resultsmentioning

confidence: 99%

Thallium(III) nitrate-mediated efficient synthesis of 2-arylpropionic acids from 1-halogenoethyl aryl ketones

Yamauchi¹,

Nakao²,

Fujii³

1987

J. Chem. Soc., Perkin Trans. 1

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Treatment of 1 -halogenoethyl aryl ketones [4'-RC,H,COCH(X)Me](1; R = H, But, OMe, Me, Ph, or Br; X = Br or CI) with TI( N03),-3H,0 and perchloric acid in a trialkyl orthoformate at 25-50 "C affords alkyl esters (3) of 2-arylpropionic acid in good-to-excellent yields via 1,2-aryl migration in substrates (1 ). The hydrolysis of esters (3) leads t o the corresponding acids, some of which are pharmaceutically important compounds. The reaction hardly occurs in methanol. The key step of the reaction is the in situ acetal formation of the starting ketone. The thallium(iit) salt acts as an effective Lewis acid catalyst for both acetal formation and halide abstraction.Several z-arylalkanoic acids have been used as important pharmaceuticals exhibiting anti-inflammatory and analgesic activities, ' various methods for preparing these compounds having hitherto been developed. A method using 1,2-aryl migration in alkyl aryl ketones and their derivatives is one of them,, the most useful example of which being a direct oxidation of alkyl aryl ketones with thallium(rI1) nitrate trihydrate (TTN).3-6 Other methods are the oxidation by (diacetoxyiodo)benzene ' or iodine-silver nitrate and the treatment of the enamines with diphenyl phosphorazidate.'The same compounds were also produced from =-halogenoalkyl aryl ketones or their acetals by 1,2-aryl shift assisted by silver salt^^.'^ or Lewis acids such as ZnBr,, SnCI,, and CoCI,, respectively. Similar reaction with the corresponding tosyl ester proceeds even thermally in the presence of calciumWe report herein another efficient synthetic method of preparing alkyl esters of 2-arylpropionic acids by the interaction of TTN with l-halogenoethyl aryl ketones l 4 which are readily available by Friedelxrafts reaction of aromatic compounds with industrially very cheap 2-halogenopropionyl halides. Results and DiscussionThe reaction was generally carried out in a stirred mixture of a l-halogenoethyl aryl ketone (l), TTN (1 mol equiv.), a trialkyl orthoformate (2), and perchloric acid at 25-50 "C for 3-30 h. The product was the corresponding 2-arylpropionic acid alkyl ester (3) and its alkaline hydrolysis afforded the corresponding acid (4) (Scheme 1). Trimethyl or triethyl orthoformate [TMOF Me ii, iii I t (4 1 Scheme 1. Reugents: i, TTN, H,O'; ii, aq. NaOH; iii, aq. HCI (2; R' = Me) or TEOF (2; R' = Et)] was used as the solvent as well as the source of an alkoxy group. Typical results are summarized in Table 1 which shows that the ease of 1,2-aryl migration is strongly affected by the substituent on the phenyl ring and also by the nature of X. Thus, introduction of an electron-releasing substituent such as methyl, methoxy, or phenyl facilitates the rearrangement and the reaction proceeds more rapidly when X = Br than when X = CI, the results being consistent with those found by Giordano et al. in silver saltmediated rearrangement reactions in methanol. l o It has been reported that the products from oxidation of alkyl aryl ketones with TTN depended remarkably on the solvent employed, and the...

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Section: Resultsmentioning

confidence: 99%

Thallium(III) nitrate-mediated efficient synthesis of 2-arylpropionic acids from 1-halogenoethyl aryl ketones

Yamauchi¹,

Nakao²,

Fujii³

1987

J. Chem. Soc., Perkin Trans. 1

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“…The keto acetal (508) 423 was obtained through normal Ar ring migration, while the ester (512) was obviously achieved by migration of the Ar 1 ring. As shown in Scheme 150, owing to the low rate of the treatment of chalcone with TTN and also the faster reaction of aldehydes and ketones with TMOF by TTN to form acetals and ketals, 424 the ketalization reaction of chalcone apparently competes with oxidative rearrangement. Hence, the oxidative rearrangement resulted in product (508) 2-Dimethoxymethyl-4,4-dimethoxycyclohexa-2,5-dienone (514) could be prepared via oxidation of 2-formyl-4methoxyphenol (513) with TMOF (4), utilizing thallium trinitrate 426,427 in methanol at À20 C while the oxidation of 2methoxycarbonyl-4-methoxyphenol furnished 2methoxycarbonyl-3,4,4-trimethoxycyclohexa-2,5-dienone (Scheme 151).…”

Section: Acetalization Reactionmentioning

confidence: 99%

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

Khademi

Nikoofar

2020

RSC Adv.

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“…Many synthetic preparations reported for such acids, involve a useful oxidative rearrangement of alkyl aryl ketones by thallium(lll) nitrate trihydrate (TTN). [3][4][5] Lead(1v) salts often show similar reactivities to thallium(lI1) and mercury(l1) salts in the oxidation of organic compounds.6-8 Indeed, Myrboh et aL9 have reported that treatment of acetophenones with lead(1v) acetate and boron trifluoridediethyl ether in benzene-methanol give methyl arylacetates in high yield via the oxidative rearrangement of the aryl group. We now report the application of this rearrangement to propiophenones for the preparation of 2-arylpropanoic acids.…”

Section: Oxidative Rearrangement Of Aryl Ethyl Ketones T O Alkyl2-ary...mentioning

confidence: 99%

“…The amount of lead(1v) salt in the mixture was determined by iodimetry at appropriate time intervals. Alkaline Hydrolj,sis qf AIkj*l 2-A rylpropanoates (3).-The alkaline hydrolysis of (2) to free acids (3) was carried out following the procedure described in reference 10 (Table 5). The yield and purity of the acid were determined by g.1.c.…”

Section: )mentioning

confidence: 99%

Oxidative rearrangement of aryl ethyl ketones to alkyl 2-arylpropanoates by lead(IV) acetate

Yamauchi¹,

Nakao²,

Fujii³

1987

J. Chem. Soc., Perkin Trans. 1

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Thallium in organic synthesis. 43. Novel oxidative rearrangements with thallium(III) nitrate (TTN) in trimethyl orthoformate (TMOF)

Abstract: From the foregoing, it is apparent that treatment of a complex, substituted hydrocarbon substrate with either elemental fluorine or a fluoroxy reagent (with radical inhibitor) comprises an effective, predictable, and regioselective process for substitution a t saturated carbon.12

Cited by 53 publications

References 2 publications

Thallium(III) nitrate-mediated efficient synthesis of 2-arylpropionic acids from 1-halogenoethyl aryl ketones

Thallium(III) nitrate-mediated efficient synthesis of 2-arylpropionic acids from 1-halogenoethyl aryl ketones

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

Oxidative rearrangement of aryl ethyl ketones to alkyl 2-arylpropanoates by lead(IV) acetate

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