Allyl chloride regioselective oxidation

This synthetic project makes provision for the regioselective oxidation of allylic hydroxyl of 13h with Jones s reactant in acetone this reaction provided the keto derivative 13i quantitatively only when we operates with small substrate quantities (few milligrams). Then the hydroxyl at C-4 has been esterified with methanesulfonyl chloride the mesylation reaction has been led in methylene chloride in presence of triethylamine at 0°C and it has brought to the formation of product 131. Then it has been substituted azide for mesyl group by the treatment of mesyl derivative 131 with sodium azide in dimethylformamide at SOX, so obtaining product 13m. 

Palladium is a useful catalyst in several reactions which lead to keto-esters. p-Keto-esters react with allylic carbonates, with catalysis by palladium, in a decarboxylative allylation reaction. y-Keto-esters are prepared, in reasonable yield, by the palladium-catalysed regioselective oxidation of Py-unsaturated esters. y-Keto-esters are obtained in good yield by the palladium-catalysed Reformatsky reaction of ethyl bromoacetate and acid chlorides. Derivatives of y-ketopimelic acid are formed by the rhodium-carbonyl-catalysed reaction of derivatives of acrylic acid with carbon monoxide. A mild method for the conversion of propiolic esters into P-keto-esters via thiol addition has been reported (Scheme 63) it has been used in a formal synthesis of ( )-thienamycin. 

Vilsmeier reaction of 1,4-dihydrobenzoyl chlorides leads to ipso- and meta-sub-stitution products. Aromatic aldehydes are isolated as a result of aerial oxidation [30]. The allylic acceptor (COX) is responsible for the double bond activation as well as the observed regioselectivity. 

As an example of carbometallation, the 1,4-carbosilylation product 218 is obtained by the reaction of dienes, disilanes and acid chlorides of aromatic and a,/i-unsaturatcd acids at 80 °C. The phenylpalladium 216 is formed by the oxidative addition of benzoyl chloride, followed by facile decarbonylation at 80 °C, and reacts with butadiene to generate the benzyl-7i-allylic complex 217. Then, transmetallation with the disilane and reductive elimination afford 4-silyl-2-butenylbenzene 218 [92], Regioselective carbomagnesation of isoprene with allylic magnesium bromide 219 catalysed by Cp2TiCl2 gives 220, which is useful for terpene synthesis [93,94],... 

More recently, these concepts have been extended to include a range of elegant amidoselenation processes. Alkenes react with benzeneselenenyl chloride and nitriles to yield 3-amido phenyl selenides in excellent yield. - Oxidative elimination of the latter provides the corresponding allylic amides (Scheme 60). Since the reaction proceeds via an episelenonium intermediate, Ae amido selenides are formed with tram stereospecificity. However, when applied to nonsymmetrical alkenes (equation 50) it only proceeds with regioselectivity. 

Allylic acetoxylation with palladium(II) salts is well known however, no selective and catalytic conditions have been described for the transformation of an unsubstituted olefin. In the present system use 1s made of the ability of palladium acetate to give allylic functionalization (most probably via a palladium-ir-allyl complex) and to be easily regenerated by a co-oxidant (the combination of benzoquinone-manganese dioxide). In contrast to copper(II) chloride (CuClj) as a reoxidant,8 our catalyst combination is completely regioselective for allcyclic alkenes with aliphatic substrates, evidently, both allylic positions become substituted. As yet, no allylic oxidation reagent is able to distinguish between the two allylic positions in linear olefins this disadvantage is overcome when the allylic acetates are to... 

Carbon-carbon double bonds, besides being susceptible to addition of oxygen or cleavage, can also react at allylic positions. Synthetic utility requires that there be good regioselectivity. Among the transition-metal oxidants, the CrOs-pyridine reagent in methylene chloride and a related complex in which 3,5-dimethylpyrazole is used in, place of pyridine are the most satisfactory for allylic oxidation. 

These organocopper intermediates were successfully trapped with electrophiles such as allyl bromide, acyl chlorides, and diphenylchlorophosphine, but not with benzaldehyde and methyl iodide. The resulting products were subjected to in situ oxidation with elemental sulfur to form stable alkenylphosphine sulfides 353 [103]. Owing to its synthetic potential, the regioselective carbometallation of substituted ynol ethers has recentiy witnessed a renaissance [91aj. Thus, the alkynyl ethers 354 were treated under different carbocupration conditions (Scheme 10.121). 

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