Synthesis regioselective oxidation

Based on these results, a novel method for the synthesis of hexose-6-aldehydes from natural carbohydrate sources has been developed by us. Preliminary results for the regioselective oxidation of the primaty alcohol group in glycosides by the dinuclear copper(ll) complex N, A-bis[(2-pyridylmethyl)-l,3-diaminopropan-2-olato] (p-acetato) dicopper(ll) perchlorate (Cu2(bpdpo), (4) are described below. 

Allais C, Constantieux T, Rodriguez J (2009) Use of p, y-unsaturated a-ketocarbonyls for a totally regioselective oxidative multicomponent synthesis of polyfunctionalized pyridines. ChemEur J 15 12945-12948... 

Regioselective oxidation by brominolysis of dioxastannolane obtained from methyl / -L-ara-binopyranoside made it possible to accomplish (after subsequent oximation and reduction) a facile synthesis of 4-amino-4-deoxy-L-arabinose, an amino-sugar found in lipopolysaccharides of some Salmonella R. mutant strains <83CPB3778>. 

Ship-in-Bottle Synthesis of Sterically Crowded Fe-Phthalocyanines in NaY Zeolite Hosts and Their Catalytic Behavior in Regioselective Oxidation of Alkanes... 

Regioselective oxidation with OT-chloroperbenzoic acid (MCPBA Scheme 32) is used in the synthesis of the male pheromone sordidin emitted by the banana weevil Cosmopolites sordidus <1995TL1043>. 

L. Den Drijver, C. W. Holzapfel, J. M. Koekemoer, G. J. Kruger, and M. S. Van Dyk, Regioselective oxidation of carbohydrates triols facile synthesis of 2,3-O-isopropylidene-/i-D-t/jreo-hexo-2,4-diulo-pyranose and l,2-0-isopropylidene-/i-D-t/jreo-hexo-2,5-diulo-pyranose, Carbohydr. Res., 155 (1986) 141-150. 

One remarkable process is the photochemical synthesis of 3,4-dihydro-2H-l,3-oxazin-4-ones from a-sulfonyloxy-(3-keto amides (obtained by coupling of P-keto-carboxylic acids with amines, followed by treatment with an iodanyl mesylate). This allows the regioselective oxidation of less-activated C—H bonds and a C—O bond formation which is unusual for a Norrish-Yang reaction [69]. The formation of a 1,6-0—C biradical has been postulated as an intermediate (Scheme 9.42). 

Yildirim, S., Franco, T., Wohlgemuth, R., Kohler, H.P., Witholt, B. and Schmid, A. (2005) Recombinant chlorobenzene dioxygenase from Pseudomonas sp. P51 a biocatalyst for regioselective oxidation of aromatic nitriles. Advanced Synthesis Catalysis, 347,1060 1073. 

It is well known that ir-allylpalladium complexes (86) are easily formed by the reaction of PdCb with P. y-unsaturated esters or ketones (85). An attempted oxidation of. y-unsaturated esters and ketones with the PdCl2/CuCl/02 catalyst system in aqueous DMF led to ir-allylpalladium complex formation as the main reaction, and the oxidation of the alkenic bond was hardly observed to a significant extent. However, in aqueous dioxane or THF, the oxidation became the main reaction, giving y-keto esters and 1,4-diketones (87), respectively, with high regioselectivity (Scheme 26).Some results are shown in Table 2. In all cases, no P-keto ester or 1,3-diketone was detected. At the end of the reaction, formation of a considerable amount of the ir-allylpalladium complex (86) was observed. y-Keto esters and 1,4-diketones are useful intermediates for Ae preparation of cyclopentanedione and cyclopentenone, respectively, by base-catalyzed cyclization. Tliis regioselective oxidation provides a unique and efficient synthetic method for y-keto ester and 1,4-diketone synthesis. 

Scheme 6.260 shows an example of the application of photooxygenation in the total synthesis of dysidiolide (539), a cdc25A protein phosphatase inhibitor, involving regioselective oxidation of the furan moiety of 540 in nearly quantitative chemical yield in the last step of the synthetic procedure.1447... 

This transformation matured to being a highly efficient tool for the synthesis of substituted alkenes [116-118]. Thus, for instance, effective palladium-catalyzed regioselective oxidative arylation of alkenes [119] were developed, which enabled oxidative coupling to proceed at ambient temperature (Scheme 9.46). 

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