Alkenes into carboxylic acids

The telomer obtained from the nitromethane 65 is a good building block for civetonedicarboxylic acid. The nitro group was converted into a ketone, and the terminal alkenes into carboxylic acids. The acyloin condensation of protected dimethyl dvetonedicarboxylate (141) afforded the 17-membered acyloin 142, which was modified to introduce a triple bond 143. Finally, the triple bond was reduced to give civetone (144)[120). 

Oxidations by oxygen and catalysts are used for the conversion of alkanes into alcohols, ketones, or acids [54]-, for the epoxidation of alkenes [43, for the formation of alkenyl hydroperoxides [22] for the conversion of terminal alkenes into methyl ketones [60, 65] for the coupling of terminal acetylenes [2, 59, 66] for the oxidation of aromatic compounds to quinones [3] or carboxylic acids [65] for the dehydrogenation of alcohols to aldehydes [4, 55, 56] or ketones [56, 57, 62, 70] for the conversion of alcohols [56, 69], aldehydes [5, 6, 63], and ketones [52, 67] into carboxylic acids and for the oxidation of primary amines to nitriles [64], of thiols to disulfides [9] or sulfonic acids [53], of sulfoxides to sulfones [70], and of alkyl dichloroboranes to alkyl hydroperoxides [57]. 

Sodium permanganate monohydrate, NaMn04 H20, which is commercially available, is used for the oxidation of alkenes to carboxylic acids [834] and of alcohols to carbonyl compounds [SJ5], the conversion of sul-finic acids into sulfonic acids [836], and the selective oxidation of sulfoxides to sulfones (sulfides are not oxidized with sodium permanganate in dioxane solutions) 837. ... 

The spectrum of applications of potassium permanganate is very broad. This reagent is used for dehydrogenative coupling [570], hydrox-ylates tertiary carbons to form hydroxy compounds [550,831], hydroxylates double bonds to form vicinal diols [707, 296, 555, 577], oxidizes alkenes to a-diketones [560, 567], cleaves double bonds to form carbonyl compounds [840, 842, 552] or carboxylic acids [765, 841, 843, 845, 852, 869, 872, 873, 874], and converts acetylenes into dicarbonyl compounds [848, 856, 864] or carboxylic acids [843, 864], Aromatic rings are degraded to carboxylic acids [575, 576], and side chains in aromatic compounds are oxidized to ketones [566, 577] or carboxylic acids [503, 878, 879, 880, 881, 882, 555]. Primary alcohols [884] and aldehydes [749, 868, 555] are converted into carboxylic acids, secondary alcohols into ketones [749, 839, 844, 863, 865, 886, 887], ketones into keto acids [555, 559, 590] or acids [559, 597], ethers into esters [555], and amines into amides [854, 555] or imines [557], Aromatic amines are oxidized to nitro compounds [755, 559, 592], aliphatic nitro compounds to ketones [562, 567], sulfides to sulfones [846], selenides to selenones [525], and iodo compounds to iodoso compounds [595]. 

One method of converting alcohols into carboxylic acids, known as Koch carbonylation, is mediated by AgOTf in the presence of weak and soft Lewis acids (eq 11). Alkenes can be similarly carbonylated albeit in much lower yields (eq 12). ... 

Various functional alkenes were similarly synthesized with high regio and E-stereoselective manner via [RuCl2(p-cymene)]2/AgSbF6 catalysed hydroarylation of phenyl or ester substituted alkynes with aromatic carbamates. The addition of 5 equiv. of pivalic acid improves the reaction in 1,4-dioxane. The alkenyl ester is converted into carboxylic acid by using 2 equiv. of LiOH, whereas phenol derivatives were deprotected by addition of 10 equiv. of LiOH [(Eq. 82)] [166]. 

The iodine-catalyzed addition of carboxylic acids to styrene derivatives generated high yields of esters and related compounds (Scheme 2.17) [24], This transition metal-free reaction used TBHP as the oxidant and was carried out under very mild conditions using an assortment of alkenes and carboxylic acids as substrates. The chemistry was quite tolerant of preexisting functional groups, and even aryl bromides were retained through the oxidation process. In addition to the styrene derivatives, aliphatic alkenes such as 1-octene were also successfully converted into esters using this approach. 

Typical nucleophiles known to react with coordinated alkenes are water, alcohols, carboxylic acids, ammonia, amines, enamines, and active methylene compounds 11.12]. The intramolecular version is particularly useful for syntheses of various heterocyclic compounds[l 3,14]. CO and aromatics also react with alkenes. The oxidation reactions of alkenes can be classified further based on these attacking species. Under certain conditions, especially in the presence of bases, the rr-alkene complex 4 is converted into the 7r-allylic complex 5. Various stoichiometric reactions of alkenes via 7r-allylic complex 5 are treated in Section 4. 

Carboxylic esters 1, having an O-alkyl group with a /3-hydrogen, can be cleaved thermally into the corresponding carboxylic acid 2 and an alkene 3. This reaction often is carried out in the gas phase generally the use of a solvent is not necessary. 

The adjacent iodine and lactone groupings in 16 constitute the structural prerequisite, or retron, for the iodolactonization transform.15 It was anticipated that the action of iodine on unsaturated carboxylic acid 17 would induce iodolactonization16 to give iodo-lactone 16. The cis C20-C21 double bond in 17 provides a convenient opportunity for molecular simplification. In the synthetic direction, a Wittig reaction17 between the nonstabilized phosphorous ylide derived from 19 and aldehyde 18 could result in the formation of cis alkene 17. Enantiomerically pure (/ )-citronellic acid (20) and (+)-/ -hydroxyisobutyric acid (11) are readily available sources of chirality that could be converted in a straightforward manner into optically active building blocks 18 and 19, respectively. 

Pyranopyrrolothiazoles can be prepared in a similar way to certain pyrano- and thiopyrano-pyrrolizines and pyrrolizinopyridines as discussed earlier. Thus, thiazolidine-4-carboxylic acid reacts with the aldehyde 179 to give a 2 1 mixture of 180 and 181 (Equation 16). This reaction is a 1,3-dipolar cycloaddition of the alkene to the 1,3-dipole formed from reaction of the amino acid amine with the aldehyde <1988T4953, 1990T2213>. The alkyne analogue of 179 is similarly converted into 182 (Equation 17). 

Recently, the conversion of alkenes or non-activated internal alkynes into the corresponding carboxylic acids and/or butenolides has been achieved through carboxylation of titanacycle intermediates of type 73 with carbon dioxide (Scheme 27).78... 

The reactions are related to the incorporation of CO and H20 into alkenes or alkynes leading to the corresponding saturated or unsaturated carboxylic acids. The general equation is shown below. Equation lb is related to the synthesis of acrylic acid discovered by Reppe [11]. 

In fluorosulfonic acid the anodic oxidation of cyclohexane in the presence of different acids (RCO2H) leads to a single product with a rearranged carbon skeleton, a 1-acyl-2-methyl-1-cyclopentene (1) in 50 to 60% yield (Eq. 2) [7, 8]. Also other alkanes have been converted at a smooth platinum anode into the corresponding a,-unsaturated ketones in 42 to 71% yield (Table 1) [8, 9]. Product formation is proposed to occur by oxidation of the hydrocarbon to a carbocation (Eq. 1 and Scheme 1) that rearranges and gets deprotonated to an alkene, which subsequently reacts with an acylium cation from the carboxylic acid to afford the a-unsaturated ketone (1) (Eq. 2) [8-10]. In the absence of acetic acid, for example, in fluorosulfonic acid/sodium... 

Carboxylic acids can be converted into the corresponding peroxy acids using peroxydisulfate in the presence of a phase transfer catalyst in good to excellent yields . When o-methylbenzoic acid was treated with sodium peroxydisulfate in the presence of Ag(I)/Cu(It), the corresponding lactone was obtained in 56% yield. Acyl radicals were also trapped by quinohnes or alkenes in the presence of peroxydisulfate to give the products in high yields. 

Schreiber and co-workers (436) prepared a library calculated to contain 2.18 million polycyclic compounds through the 1,3-dipolar cycloaddition of a number of nitrones with alkenes supported on TentaGel S NH2 resin (Scheme 1.83). (—)-Shikimic acid was converted into the polymer bound epoxycyclohexenol carboxylic acid 376 (or its enantiomer), coupled to the resin via a photolabile linker developed by Geysen and co-workers (437) to allow release of the products from the resin in the presence of live cells by ultraviolet (UV)-irradiation. A range of iodoaromatic nitrones (377) was then reacted with the ot,p-unsaturation of the polymer-bound amide in the presence of an organotin catalyst, using the tandem esterification/ dipolar cycloaddition methodology developed by Tamura et al. (84,85) Simultaneous cyclization by PyBrop-mediated condensation of the acid with the alcohol... 

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