Periodinane primary alcohols

After successful installation of the first two stereocenters, our attention was focused on elaboration of the terminal alkene in 64 (Scheme 6.9). Treatment with disiamylborane followed by oxidative workup afforded primary alcohol 65 in good yield (70-85 %). A side product containing a mixture of two diastereomers (66) was also observed and resulted from conjugate addition of the alkoxide formed during basic workup onto the unsaturated ester. Maintaining the temperature at 0 °C by a slow, dropwise quench during the oxidative workup was necessary to minimize the amount of the undesired cyclization product (66). Subsequent oxidation of the primary alcohol 65 using Dess-Martin periodinane [28] and a Pinnick oxidation afforded carboxylic acid 67 [29]. 

A selective oxidation of a primary alcohol in the presence of a secondary one in a complex substrate can be done with 88% yield with Dess-Martin periodinane. The authors comment that Selective oxidation of the primary alcohol proved to be unexpectedly straightforward. Thus, treatment with Dess-Martin periodinane afforded aldehyde with 88% yield, with complete selectivity for the primary alcohol. Despite the large number of documented applications of this mild oxidation, no study has yet addressed its potential for selective oxidations of sterically differentiated diols . 

The periodinane (10) may also be prepared from o-iodobenzoic acid by oxidation with potassium bromate and then treatment with acetic anhydride18 (see Expt 6.36 for detailed formulation). It should be noted that the organic derivatives of pentacoordinate iodine(v) are termed periodinanes.18b This compound (the systematic name is l,l,l-triacetoxy-2,l-benzoxiodol-3(3//)-one) has found use as an oxidant of primary alcohols to aldehydes and alicyclic ketones to secondary alcohols it is claimed to have advantages over the chromium-based oxidation reagents. 

Like the Swem oxidation, the Dess-Martin periodinane (DMP) reagent oxidizes primary alcohols to aldehydes and secondary alcohols to ketones without using chromium or other heavy-metal compounds. The reaction with DMP takes place under mild conditions (room temperature, neutral pH) and gives excellent yields. The DMP reagent, which owes its oxidizing ability to a high-valence iodine atom, is a commercially available solid that is easily stored. 

The Dess-Martin periodinane reagent, used to oxidize primary alcohols to aldehydes and secondary alcohols to ketones. The DMP reagent uses a high-valence iodine atom as the oxidizing species, (p. 473)... 

MnOi oxidizes allylic and benzylic alcohols to the corresponding aldehydes. Oxidation of primary saturated alcohols wdth Mn02 is also possible but much slower. Therefore it is possible to oxidize an allylic or benzylic alcohol in the presence of an unprotected primary alcohol w ith MnO. The yields of this procedure. strongly depend on the activation grade of MnO. Other oxidation methods are Dess-Martin periodinane, IBX," TPAP or DMSO/QOiCB. ... 

The following Swern oxidation is an inexpensive, mild and fast transformation. It provides aldehydes starting from primary alcohols in the absence of water, exclusively. Other mild oxidation methods for the formation of aldehydes are known Dess-Martin periodinane (DMP), o-iodoxybenzoic acid (IBX), chromium(III) reagents, tetramethylpiperidine 7V-oxide and sodium hypochlorite (TEMPO/NaOCl), tetrapropylammonium perruthenate and N-methylmorpholine 7V-oxide (TPAP/NMO), " and palladium(II)-catalyzed oxidations are reported. ... 

The TPAP/NMO system [24] and the Dess-Martin periodinane [31] have been widely applied for oxidizing alcohols in complex natural product synthesis. Although both reagents are commercially available, they have so far found relatively little use in carbohydrate chemistry for oxidation of primary alcohols to aldehydes [44,45]. 

Upon deprotection of the benzyl group under hydrogenolysis conditions, and oxidation of the resulting primary alcohol to the corresponding aldehyde with Dess-Martin periodinane [74], compound 137 was obtained. Aldehyde 137 is the coupling partner for the NHK reaction with the vinyl iodide 82. 

In the final stages of the total synthesis of ustiloxin D, M.M. Joullie and co-workers had to install the amide side-chain onto the already assembled macrocycle.To achieve this goal, the macrocyclic primary alcohol was treated with the Dess-Martin periodinane to generate the corresponding aldehyde, which was subsequently treated with sodium chlorite to afford the carboxylic acid. The carboxylic acid was then coupled with the benzyl ester of glycine to complete the installation of the side-chain in 66% yield for three steps. 

Another more environmentally friendly class of oxidants than chromium species involve hypervalent iodine compounds, such as the reagent commonly referred to as the Dess-Martin periodinane (DMP). Hypervalent means a compound with a greater electron count than predicted by the octet rule. The name DMP derives from the two chemists that developed its reactivity, and its use is called the Dess-Martin oxidation. Once again, primary alcohols are oxidized to aldehydes, while secondary alcohols are oxidized to ketones, and tertiary alcohols are unreactive. Hence, DMP performs the same transformations as PCC and the Swern oxidation (same products as in Example 10.11). 

Primary alcohols are oxidized to aldehydes using the Dess-Martin periodinane (DMP). 

Protected keto alcohol 235 was prepared via oxidative cleavage, and Zn(BH4)2 reduction of the aldehyde provided the primary alcohol which spontaneously cyclized to the corresponding hemiketal. Treatment with TlPSCl and imidazole afforded the TIPS-protected keto alcohol 235 (three steps, 48% overall yield). Conjugate addition was successfully carried out with MeLi and DMPU in ether to provide 236 as a single diastereoisomer. O-Desilylation and tosylation of the primary alcohol was followed by ozonolysis of the furyl substituent to provide carboxylic add 237 in 53% overall yield. The conversion of carboxylic add 237 to the corresponding aldehyde 238 required formation of the mixed anhydride, NaBH4 reduction to the primary alcohol, and Dess Martin periodinane oxidation (30% overall yield). 

One of the best methods of aldehyde synthesis is by oxidation of primary alcohols, as we saw in Section 13.5. The reaction is often carried out using the Dess-Martin periodinane reagent in dichloromethane solvent at room temperature ... 

Primary alcohols are oxidized to either aldehydes or carboxylic acids, depending on the reagents chosen and the conditions used. Older methods were often based on Cr(Vl) reagents such as Cr03 or Na2Cr207, but a more common current choice for preparing an aldehyde from a primary alcohol in the laboratory is to use the I(V)-containing Dess-Martin periodinane in dichloromethane solvent. 

Dess-Martin periodinane (Section 17.7) An iodine-based reagent commonly used for the laboratory oxidation of a primary alcohol to an aldehyde or a secondary alcohol to a ketone. 

When 90 was heated in toluene, the hydroxylamine added to the alkyne to afford nitrone 91 (after tautomerization of a presumed intermediate N-hydroxyenamine) which was trapped by styrene in an intermolecular 1,3-dipolar cycloaddition to provide 92. An oxidation state adjustment (with removal of the chiral auxiliary) gave 93. The TBDPS protecting group was removed and the resulting primary alcohol was oxidized with IBX (94) (related to the Dess-Martin periodinane) to give aldehyde 95. Application of the Yamamoto variation of the Peterson olefmation gave 96 with decent control over olefin geometry. 

The Dess-Martin periodinane ( DMP ) reagent, U,l-tris(acetyloxy)-l,l-dihydro-l,2-benziodoxol-3(l//)-one, has also been used in several complex syntheses for the oxidation of primary or secondary alcohols to aldehydes or ketones, respectively (e.g., M. Nakatsuka, 1990). It is prepared from 2-iodobenzoic add by oxidation with bromic add and acetylation (D.a Dess, 1983). 

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