Wakamatsu reaction

Wagner equation Wagner number Wakamatsu reaction Waldhof fermentor Walkman Wallace plasticity Wallach procedure Wall baffles Wallboard Wall geometries Wallpaper paste Wallpaper pastes Wallpapers Wall plaster Walnut oil... 

Carbonylation of Aldehyde. This method (40,41) is noteworthy as an efficient one-step synthesis. Wakamatsu Reaction... 

Wafer contamination, in ion implantation systems, 14 445-446 WAG process, 13 626 Wait and see problems, 26 1025, 1028 Wakamatsu reaction, 2 573 Wakame... 

Hydroformylation (0x0 reaction) affords aldehyde and an amide is added to the aldehyde under these reaction conditions to produce an acylamino acid as shown in eq. (17.32). This reaction is named the Wakamatsu reaction in which an amino acid is produced directly from an olefin [46,77]. Cobalthydrocarbonyl (HCo(CO)4) is a strong acid as the aldehyde reacts with amide to afford an aminoalcohol, and a dehydration condensation with HCo(CO)4 forms a carbon-Co bond, and carbonylation and hydrolysis to produce the acylamino acid [46,77]. The carbonylation... 

The following order of initiation rate constants was found by Grubbs et al. for 71a and some precatalysts containing one phosphine ligand 56d< 56k 71a<56h (cf. Scheme 15 for structures of 56d,h,k) [48b, 55]. Thus, 71a shows a rate of initiation comparable to that of 56k but three orders of magnitude higher than that of 56d. Nevertheless, 56d appears to be more reactive in RCM reactions than 71a [56]. Wakamatsu and Blechert were the first to report that the activity of precatalysts related to 71a can be dramatically enhanced by modification of the benzylidene unit [56]. For example, RCM of 75 using 1 mol% of BINOL-derived complex 71b yields the azacyclic product 76 in quantitative yield within 20 min (Eq. 10), whereas with 56d only 4% of 76 was obtained under these conditions [56]. 

Ojika, M., Wakamatsu, K., Niwa, H. and Yamada, K. 1987. Ptaquiloside, a potent carciogen isolated from bracken fern, Pteridium aquilinum var. latiusculum. structure elucidation based on chemical and spectral evidence, and reactions with aminoacids, nucleotides and nucleosides. Tetrahedron 43 5261-5274. 

The amidocarbonylation of aldehydes provides highly efficient access to N-acyl a-amino acid derivatives by the reaction of the ubiquitous and cheap starting materials aldehyde, amide, and carbon monoxide under transition metal-catalysis [1,2]. Wakamatsu serendipitously discovered this reaction when observing the formation of amino acid derivatives as by-products in the cobalt-catalyzed oxo reaction of acrylonitrile [3-5]. The reaction was further elaborated to an efficient cobalt- or palladium-catalyzed one-step synthesis of racemic N-acyl a-amino acids [6-8] (Scheme 1). Besides the range of direct applications, such as pharmaceuticals and detergents, racemic N-acetyl a-amino acids are important intermediates in the synthesis of enantiomeri-cally pure a-amino acids via enzymatic hydrolysis [9]. 

Photoindnced electron transfer in the presence of a sensitizer (9,10-diphenylanthracene) also generates the same anion-radical. However, its disintegration proceeds within the solvent (acetonitrile) cage. Inside the cage, the 4-nitrobenzyl radical and thiocyanate ion unite anew, but in this case, by their soft-to-soft ends. This nucleophilic reaction takes place faster than the back electron transfer does. The final, stable product of the whole process is 4-nitrobenzyl- o-thiocyanate (Wakamatsu et al. 2000) ... 

Since Wakamatsu serendipitously discovered amidocarbonylation while performing the cobalt-catalyzed hydroformyla-tion of olefins in 1971, this unique carbonylation reaction, affording a-amino acids directly from aldehydes, has been extensively studied.More recently, palladium-catalyzed processes have been developed to expand the scope of this reaction.The Pd-catalyzed amidocarbonylation has been applied to aldehydes,aryl halides, and imines. As a related reaction, lactamization " of aryl halides catalyzed by a rhodium complex has also been developed. 

Although the standard amidocarbonylation reaction involves an aldehyde and an amide, benzyl chloride can be used as the reactant. The amidocarbonylation of benzyl chloride was first reported by Wakamatsu eta/, in 1976 using Co2(CO)8 as catalyst precursor. This process was revisited by de Vries et al. in 1996 and iV-acetylphenylalanine 8 was obtained in 82% yield under the optimized conditions (Scheme 2)." Since the Co-catalyzed amidocarbonylation is carried out in the presence of CO and H2, formylation of benzyl chloride takes place first to form phenylacetalde-hyde in situ. In this particular case, as Scheme 2 illustrates, A-acetylenamine 10 is formed as intermediate, followed by the chelation-controlled HCo(CO)4 addition to give alkyl-Co intermediate II. Insertion of CO to the carbon-Co bond of II, forming acyl-Co complex 12, followed by hydrolysis affords 8 and regenerates active Co catalyst species. 

Fuerstenau and Wakamatsu (1975) examined alumina as a sorbent for dodecyl sulfonate (DS) ions. Alkyl sulfonates, R-SO3, do not participate in substantial ligand exchange reactions with alumina. 

Another route to carboxylic acids from aldehyde products (once again, generally produced via hydroformylation catalysis) was discovered by Wakamatsu and coworkers. They reported the carbonylation of aldehydes and primary organic amides to produce A-acylamino acids (equation 16). The reaction is efficiently catalyzed by HCo(CO)4 at 100 °C and 140 bar of 3 2 H2/CO (hydrogen is needed to help stabilize HCo(CO)4). Yields of over 90% of the appropriate... 

The amidocarbonylation reaction was discovered by Wakamatsu [1], who demonstrated the synthesis of a range of A -acyl amino acids through the cobalt carbonyl-catalyzed reactions of various combinations of aldehyde plus amide, with carbon monoxide (eq. (1)). Some aspects of the mechanism of aliphatic aldehyde amidocarbonylation have been examined by both Pino and co-workers [2] and by Getman [3], Magnus and Slater [4] subsequently investigated the scope of this synthesis for variety of A -substituted amide co-reactants and C-sub-stituted aldehydes. Further mechanistic revisions were proposed involving acyl-iminium species. 

An interesting reaction discovered by Wakamatsu involves the cobalt-catalyzed carbonylation of aldehydes in the presence of primary amides to give A-acylamino acids in high yield (equation 26). By combining this reaction with known catalytic routes to aldehydes, for example isomerization of allyl alcohols or hydroformylation of alkenes, it is possible to achieve the direct synthesis of A-acylamino acids from precursors other than aldehydes. ... 

Not only changing the ligand sphere but also the addition of a co-catalyst can dramatically increase catalyst-efficiency. In an interesting exanq>le is the cobalt-catalyzed amido-carbonylation. In a perfectly atom economic way N-acylamino acids can be produced fi om simple amides, aldehydes and carbon monoxide. Although amidocarbonylation reactions which were originally developed by Wakamatsu in the early seventies cannot compete commercially against cheap natural sources or fermentation, for non-natural amino acids this salt fi ee process must be considered as a viable alternative to the conventional Strecker reaction. 

In the first total synthesis of elaiophylin (azalomycin B 181), glycosidation of P-hydroxy ketone 178 and glycal 177 was examined (Scheme 26) [111]. NBS-promoted glycosidation [112] followed by debromination with -Bu3SnH-AIBN was first applied to give 179 in only a 30% yield. Then, the Wakamatsu procedure using CSA-MS 4A [113] was found to afford the desired 179 in 80% yield as the sole anomer, which led to 181 via aldol reaction of the (Z)-boron enolate of the ketone 179 with dialdehyde 180. 

Amidocarbonylation is the only transition metal-catal) ed multi-component reaction, by which the amino acid framework is constructed directly from simple building blocks. [73] In the early 1970s, Hachiro Wakamatsu at Ajinomoto discovered by chance the cobalt-catalysed amidocarbonylation during investigation of the Oxo process with acrylonitrile, where he also found traces of -aminobutyric add. To determine the mechanism of this side-reaction, he... 

An efficient three-component coupling reaction for the synthesis of Af-acyl-a-amino acids from aldehydes, amides, and carbon monoxide, namely, amidocarbonylation, was first described by Wakamatsu in 1971.Recently, amidocarbonylation has successfully been catalyzed by palladium (Scheme The reaction would proceed as follows. 

While I. Wender et al, [199] in the case of cyclohexene observed differences in the reaction velocity only up to a factor of 1.5 with different solvents, Iwanaga et aL [200] and also Wakamatsu et al. [201] stated a 6 times higher reaction velocity in the conversion of acrylonitrile with methanol as solvent compared to ben2ene. 

Takahashi, Y, Endoh, R, Ohaku, H., Wakamatsu, K., and Miyashi, X, Triplet-state electron-transfer reactions of phenylcyclopropane with quinones,/. Chem. Soc., Chem. Common., 1127, 1994. 

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