Cleavage of the 1,3-Dithiane Protective Group

Prato, M.; Quintily, U.; Scorrano, Gianfranco; Sturaro, A.

doi:10.1055/s-1982-29900

Cited by 31 publications

(10 citation statements)

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“…Neutral or basic methods, including metal salts [12,18,25,26], DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) [27], alkylation of the dithiane moiety [28], as well as mildly acidic conditions with Amberlyst resin [29] were tried out. All methods gave either complex product mixtures or yields that were inferior to the standard HgO/HgCl 2 procedure.…”

Section: Resultsmentioning

confidence: 99%

Investigations into the preparation of sila-β-diketones via 2-trimethylsilyl-1,3-dithianes: structural characterization of a second polymorph of bis(2,2,6,6-tetramethyl-2-sila-3,5-heptanedionato)copper(II)

Claessen

Kornilov

Banger

et al. 2004

Journal of Organometallic Chemistry

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Section: Resultsmentioning

confidence: 99%

Investigations into the preparation of sila-β-diketones via 2-trimethylsilyl-1,3-dithianes: structural characterization of a second polymorph of bis(2,2,6,6-tetramethyl-2-sila-3,5-heptanedionato)copper(II)

Claessen

Kornilov

Banger

et al. 2004

Journal of Organometallic Chemistry

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“…Methods for the hydrolysis of thioacetals continue to appear. Reagents that have been described include a polystyryl-mercury(I1) trifluoroacetate combination, which retains the metal on the resin,2o2 lead(rv) dioxide and boron trifluoride etherate, 203 aqueous hydrochloric acid in dioxan containing dimethyl s u l p h o~i d e ,~~~ methyl-bis(methy1thio)sulphonium hexachloroantimonate, 204 and iodoxybenzene, catalysed by toluene-p-sulphonic acid.17 Dithioacetals derived from ethane-lY2-dithiol may be cleaved with dimethyl sulphoxide in combination with either t-buty1205 or trimethylsily1206 bromides and iodides. Regeneration of ketones from ethanediyl-SS-acetals via the lithium-di-isopropylarnide-promoted fragment at ion to the thioketone and subsequent hydrolytic work-up only gives satisfactory yields for aryl methylketone Dithioacetal SS-dioxides are rapidly cleaved in hot methanolic hydrochloric acid solution.…”

Section: Protection and Deprotection Of Aldehydes And Ketonesmentioning

confidence: 99%

Aldehydes and ketones

EYLEY¹

1985

General and Synthetic Methods

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Oxidative Methods.-Further studies of oxidations using sodium hypochlorite in glacial acetic acid have shown that secondary alcohols may be oxidized to ketones in the presence of primary a1cohols.l In one example where epimerization of the ketonic product was possible, isomerization was not observed under the reaction conditions. The easily stored calcium hypochlorite also oxidizes secondary alcohols to ketones.2 Yields are high in dichlorornethane or acetronitrile containing acetic acid. cr-Diols are cleaved oxidatively to aldehydes or ketones, depending on the starting materiaL3 A hypochlorite may be used as an oxidant for secondary alcohols in various solvents (dichloromethane, carbon tetrachloride, ether, or ethyl acetate) in the presence of catalytic amounts of the hypochlorite form of the commercial resin IRA goo.* This method, allowing a non-aqueous work-up to be employed, may prove advantageous for the preparation of water-soluble products. Sodium bromate, in the presence of cerium(1v) ammonium nitrate or cerium(1v) sulphate, also oxidizes secondary alcohols in preference to primary alcohol^.^The uses of the versatile oxidant pyridinium chlorochromate have been reviewed.6 Pyridinium chlorochromate has been used for the oxidation of methyl 5-hydroxypentanoate to the aldehyde,' an intermediate useful in the synthesis of leukotrienes, and the same reagent oxidatively cleaves secondary vicinal diols to the corresponding aldehydes.8 The reactivity of the chlorochromate ion as an oxidant can be influenced by the counter-ion. For example, the 4-dimethylaminopyridinium salt is a mild, selective reagent for the oxidation of allylic and benzylic alcohols. Pyridinium fluorochromate oxidizes primary and secondary alcohols to aldehydes and ketones respectively in dichloromethane solution, and shows a less pronounced acidity compared with the chloro-

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“…Many procedures are available in the literature for preparing thioacetals [ 3 ], but their deprotection to the parent carbonyl compounds is not always an easy process. In recent years various hydrolytic [ 4 ] or oxidative methods [ 5 , 6 ] have been reported for dethioacetalizations and in the last two decades or so numerous reagent combinations have been documented for deprotection of thioacetals, including clay supported ammonium ion [ 7 ], ferric or cupric nitrates [ 8 ], zirconium sulfonyl phosphonate [ 9 ], oxides of nitrogen [ 10 ], air/bismuth(III) nitrate [ 11 ], Fe(phen) 3 (PF 6 ) 3 [ 12 ], DDQ [ 13 ], SeO 2 /AcOH [ 14 ], hν/pyrylium/O 2 [ 15 ], N-fluoro-2,4,6-trimethylpyridinium triflate-water system [ 16 ], methylene green/visible hν [ 17 ], SbCl 5 /N 2 [ 18 ], GaCl 3 /H 2 O or GaCl 3 /MeOH/O 2 [ 19 ], (CF 3 CO 2 ) 2 IPh [ 20 ], m -CIC 6 H 4 CO 3 H/CF 3 CO 2 H [ 21 ], NaNO 3 /aqueous solution (NO + , H 2 ONO + , ClNO) or t -butyl hypochlorite (Cl + ) in anhydrous CCl 4 [ 22 ], t -butyl bromide (or iodide)/DMSO [ 23 ], DMSO/HCl/H 2 O [ 24 ], TMSI (Br)/DMSO [ 25 ], LiN(I-C 3 H 7 ) 2 /THF [ 26 ], HgO/35% aqueous HBF 4 [ 27 ], benzeneseleninic anhydride [ 28 ], periodic acid [ 29 ], isoamyl nitrite [ 30 ], O-mesitylenesulfonyl hydroxylamine [ 31 ], Et 3 O + BF 4 - [ 32 ], MeI in moist acetone [ 33 ] or in 96% methanol [ 34 ], ceric ammonium nitrate (CAN) in aqueous CH 3 CN [ 35 ...…”

Section: Introductionmentioning

confidence: 99%