Oxidation with Jones reagent

The sisyl ether is stable to Grignard and Wittig reagents, oxidation with Jones reagent, KF/18-crown-6, CsF, and strongly acidic conditions (TsOH, HCl) that cleave most other silyl groups. It is not stable to alkyllithiums or LiAlH4. 

The synthetic sequence, which shows only the succesful solutions adopted in every step, is outlined in Scheme 13.1.11. Reaction of l Chloroadamantan-4-one (39) [15] with sodium-potassium alloy in ether gave a mixture of ketonic and hydroxylated material which upon oxidation with Jones reagent gave 7-methylenebicyclo[3.3.1]nonan-2-one (40) in 75% yield. Reduction of 40 with sodium borohydride gave the alcohol 41 which could be also obtained in better yields from l-chloroadamantan-4-one with a large excess of sodium-potassium... 

Ozonolysis of 160, followed by oxidation with Jones reagent, esterification with diazomethane, reduction of the ketone with diborane... 

The acid 350 was demethylated with pyridine hydrochloride, then realkylated with benzyl bromide in aqueous potassium hydroxide to give 351. The latter was converted to the diazoketone 352 by the sequential treatment of 351 with oxalyl chloride and etheral diazomethane. Reaction of 352 with concentrated hydrobromic acid gave the bromoketone 353. The latter was reduced with sodium borohydride at pH 8 -9 to yield a mixture of diastere-omeric bromohydrins 354. Protection of the free hydroxyl as a tetrahydro-pyranyl ether and hydrogenolysis of the benzyl residue afforded 355. The phenol 355 was heated under reflux with potassium m/V-butoxide in tert-butyl alcohol for 5 hr to give a 3 1 epimeric mixture of dienone ethers 356 and 357 in about 50% yield. Treatment of this mixture with dilute acid gave the epimeric alcohols 358 and 359. This mixture was oxidized with Jones reagent to afford the diketone 349. 

Solutions of ytterbium in liquid ammonia are capable of reducing aromatic systems to 1,4-dihydroaromatics or alkynes to trans alkenes [293]. The a,fi-unsaturated cholest-4-en-3-one was reduced to eholestanone in 80% yield by threefold excess of ytterbium in ammonia followed by oxidation with Jones reagent (Scheme 16). In the absence of a proton source, (HOEt) and THF as co-solvent, the pinacol dimer was obtained as the major product. 

The conditions of Jones oxidation are compatible with complex organic compounds containing functional groups such as esters, ketones, amides and alkenes. For example, ethyl 3-hydroxy-4-pentenoate (7.3) on oxidation with Jones reagent gave ethyl 3-oxo-4-pentenoate (Nazarov s reagent) (7.4). 

Jones reagent in acetone (1, 142-143 2, 70-71 3, 54). Benzoins are oxidized to benzils in about 90-95% yield by oxidation with Jones reagent in acetone. The two-... 

Adamantane-2-earboxyUe acU. In a new, convenient synthesis of adamantane-2-carboxylic acid (4), adamantanone (1) is treated with dimethyloxosulfonium methylide to give 2-mcthyIeneadaman(ane epoxide (2). This is rearranged by treatment with boron trifluoride etheratc to the aldehyde (3, unstable). Oxidation with Jones reagent gives (4) in an overall yield of about 70% from (1). 

A special category of ethers are trimethylsilyl ethers. Trimethylsilyl ethers of primary alcohols, on treatment with Jones reagent, give acids [590]. On treatment with A-bromosuccinimide under irradiation, trimethylsilyl ethers yield esters [744]. Secondary alkyl trimethylsilyl ethers are converted into ketones by oxidation with both reagents [590, 744, 981]. Oxidation with Jones reagent is regiospecific the 2-ferf-butyldimethylsilyl 11-Krf-butyldiphenylsilyl ether of 2,11-dodecanediol is oxidized only in the sterically less hindered position [590]. Trimethylsilyl ethers of tertiary alcohols are degraded by periodic acid to carboxylic acids with shorter chains [755] (equations 336-339). 

The reagent reacts stereospecifically with (- )-carvone (1) to give the bicyclic ketone (2).2 Reduction of (2) followed by oxidation with Jones reagent gives an... 

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