Ketones 2-iodoxybenzoic acid

Carbonyl compounds can be functionalized in the a-position under various conditions. Treatment of ketones with (diacetoxyiodo)benzene 3, iodosoben-zene 5, or 2-iodoxybenzoic acid (IBX) 7 under basic conditions provides effi-... 

One example is Swern oxidation, which uses oxalyl chloride and DMSO and is particularly suitable for the selective oxidation of alcohols to aldehydes or ketones. The disadvantages of this oxidation method are the need for low temperatures, the smell of the dimethyl sulfide formed and the possible oxidation of other heteroatoms. Dess-Martin periodinane (DMP, 5) or iodoxybenzoic acid (IBX, 6) are also common oxidizing agents. The main advantage of these two methods is the short reaction time at room temperature. However, typical problems are the low solubility of IBX and the formation of byproducts. In this context, Finney et al. have reported an interesting procedure avoiding these problems by a variation of the temperature IBX is sufficiently soluble in solvents such as ethyl acetate or dichloromethane at elevated temperatures, whereas it is insoluble in these solvents at room temperature. Because of this, the remaining IBX as well as the IBX-derived byproducts can be separated from the reaction mixture by simple filtration. These reisolated IBX byproducts can then be reoxidized and reused. 

From alcohols or ketones via oxidation with o-iodoxybenzoic acid (IBX) HO... 

One step oxidation of alcohols or ketones to enones (see also Saegusa) selective oxidation of benzylic groups (methyl to aldehydes) by o-iodoxybenzoic acid (IBX). 

A popular oxidizing agent that effects rapid oxidation of primary or secondary alcohols to aldehydes or ketones is the Dess-Martin reagent. This is the hypervalent iodine(V) compound 46, prepared from 2-iodoxybenzoic acid 45 (IBX) (6.40). Both IBX and the Dess-Martin reagent are potentially explosive and should be handled with care. 

Oxidation of Alcohols to Aldehydes and Ketones. Hyper-valent iodine compounds have powerful oxidizing capabilities. However, IBX possesses different properties than many similar oxidants, such as the related analogs iodoxybenzene and m-iodoxybenzoic acid. Until recently, the major application of IBX was its use in DMSO for the oxidation of primary alcohols to aldehydes at room temperature, without the danger of over-oxidation to carboxylic acids. The related iodo-oxy reagents oxidize benzyl alcohols to benzaldehydes at elevated temperatures in benzene (80 °C, 5-10 h) or in acetic acid (rt, 24 h), while IBX oxidizes the same compounds in 15 min (or less) at room temperature. IBX is equally effective for the oxidation of secondary alcohols to ketones under analogous conditions. Even sterically hindered alcohols are readily oxidized. Bomeol undergoes smooth oxida-... 

DMP with high purity by the original procedure therefore, a few modifications have been suggested. In addition, DMP has been successfully used in the syntheses of polycyclic heterocyclesand in the removal of thioketals and thioacetals. It should be mentioned that other hypervalent iodine compounds can be used as oxidants as well, especially for the o-iodoxybenzoic acid (IBX), the precursor to DMP, which can oxidize tertiary cyclic allyl alcohol into O, y0-unsaturated cyclic ketones and secondary amines into imines and can convert epoxides or aziridines into corresponding of-hydroxy ketones or Q -amino ketones. 

Conversion of silyl enol ethers of ketones to a,p-unsaturated ketones or coupling to 1,4-diketones by means of Ag20 or Pd(ll) for a one pot conversion of ketones, aldehydes or alcohols to a,p-unsaturated ketones (aldehydes) with iodoxybenzoic acid see Nicolaou. 

The protected butane-1,2,3,4-tetraol 15, easily available in three steps from D-tartaric add diethyl ester, was the starting material for the synthesis of (+)-phomopsohde B (Scheme 2.4). Thus, IBX (2-iodoxybenzoic acid) oxidation of the primary alcohol followed by HWE olefination with a chiral phosphonate derived from L-lactic add (not depicted) gave a,fi-enone 16. Stereoselective reduction of the ketone carbonyl and acidic deavage of the acetal moiety furnished triol 17. Selective protection of the two secondary hydroxyl groups was achieved through triple silylation with subsequent selective desilylation of the primary OTBS group. 

Catalyst. 4-Methoxypyridine IV-oxide has been shown to enhance the reactivity of o-iodoxybenzoic acid (BX) in the dehydrogenation of carbonyl compounds (eq 14). The complex formed between BX and 4-methoxypyridine Af-oxide promotes the oxidation of ketones and aldehydes with a broad scope of functional groups to form a, 8-unsaturated carbonyl compounds at room temperature. 

Related isoflavones have been prepared, using SPOS, by Harikrishnan and Showalter. Resin-bound salicyl aldehyde derivatives 336, immobilized via a traceless silyl linker unit, were prepared and treated with a Grignard reagent to introduce the first point of diversity. Subsequent re-oxidation with 2-iodoxybenzoic acid (IBX), and deprotection of the methoxymethyl (MOM) group provided ketone 338. Treatment of ketone 338 with amide acetals promoted an unusual cyclization, which concurrently installed R to give 339. Final traceless cleavage with CsF or TBAF releases isoflavones 340 (Scheme 3.59). 

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