Domino reactions olefination

The hydroformylation reaction strategy has recently been extended, in a novel way, to the manufacture of primary amines by hydroaminomethylation of olefins with ammonia in a two-phase system. Thus, 1-pentene was reacted with ammonia here hydroformylation to an aldehyde, with CO and H2, with subsequent reductive amination occurs in a domino reaction. The catalyst was Rh/Ir/TPPS (Zimmermann et al., 1999). 

One may improve efficiency of an o-DPPB directed hydroformylation by incorporating this reaction into sequential transformations (domino reactions) [16]. The hydroformylation itself should be ideally suited for such a purpose, since this reaction provides under fairly mild reaction conditions access to the synthetically valuable aldehyde functionality. The aldehyde itself should be ideally suited to allow for further skeleton-constructing reactions. One type of sequential transformations employing the hydroformylation reaction as a key step is the hydroaminomethylation of olefins originally discovered by Reppe [17]. However, efficient control of diastereoselectivity in the course of this hydroaminomethylation reaction was unknown [18, 19]. 

A dramatic improvement in this new round trip radical domino processes developed by Curran s group was presented by Takasu, Ihara and coworkers. The new method relies on the introduction of a conjugated ester moiety at the terminal olefin, thereby effecting an acceleration of the domino reaction accompanied with an enhancement of the regio- and stereoselectivity [81]. Thus, reaction of 3-196 with Bu3SnH led to a 4 3 mixture of the two diastereomeric tricycles 3-197 and 3-198 in 83 % yield. In this process, the vinyl radical 3-199 is initially formed, but this smoothly cyclizes in 5-e%o-trig manner to give radical 3-200 (Scheme 3.52). Due to... 

Hyldtoft, L, Madsen, R, Carbohydrate carbocyclization by a novel zinc-mediated domino reaction and ring-closing olefin metathesis, J. Am. Chem. Soc., 122, 8444-8452, 2000. 

Aliphatic amines are among the most important bulk and fine chemicals in the chemical and pharmaceutical industry [12]. Hydroaminomethylation of olefins to amines presents an atom-economic, efficient and elegant synthetic pathway toward this class of compounds. In hydroaminomethylation a reaction sequence of hydroformylatioti of an olefin to an aldehyde with subsequent reductive amination proceeds in a domino reaction [Eq. (4)] [13]. 

Efficient domino reactions of the alkenyl iodide 453 with CO, aUene, and piperidine proceeded to give 456 in very high yield (80 %) after six-step reactions [172], CO is the most reactive, and CO insertion is followed by olefin insertion to generate 454. Then allene insertion occurs after the second CO insertion. Finally, the TT-allylpalladium intermediate 455 is trapped by the amine to yield 456. 

Various types of domino reactions have been reported in the recent past. The sequential or cascade combination of an olefin metathesis with an intramolecular Heck reaction provides access to various bicycUc spirocyclic ring systems in good yields. Recently, a one-pot metathesis-Heck cascade was employed in the constraction of various ring systems (Scheme 57). " ... 

Cha and coworkers [15] described an interesting example of a radical/cation-mediated domino reaction for the stereoselective preparation of bicyclo[5. B.Ojdecan-3-ones 31 using aminocyclopropane 30 as substrate which was prepared by employing an intramolecular Kulinkovich cydopropanation of olefin-tethered amide. 

Starting from tetrahydrocyclopenta[f)]furan-2-one 342, enyne 343, the substrate for the domino reaction, was prepared in 12 steps and with an overall yield of 45%. Exposure of 343 to the electron-rich gold(I) complex (t-Bu)2P(o-biphenyl)AuCl at room temperature afforded cis-hydrindanone 344 in 78% yield as a single stereoisomer (Scheme 14.54). The postulated mechanism involved Au(I) activation of the alkyne to initiate the cationic olefin cyclization of 346 to give carbocation 347, which then underwent a pinacol rearrangement to the final product 344. An originally attempted Lewis acid-catalyzed domino Prins/pinacol rearrangement of... 

Tandem or domino reactions using hydroformylation as the first step allow the immediate transformation of the formed aldehydes into other valuable chemical compounds (see Chapter 5) [41]. As discussed previously, the hydrogenation of olefinic substrates or product aldehydes is a commonly observed side reaction in the hydroformylation with Ru complexes. On the other hand, the reduction of the aldehydes can be desired. 

Keywords 2-Azido-3-arylacrylates, terminal alkenes, dichloromethane, palladium acetate, tri-fluoroacetic acid (TEA), oxygen-atmosphere, room temperature, domino reaction, intramolecular cyclization followed by olefination, 3-alkenyl indoles... 

On the other hand, several groups have also recently developed asymmetric domino reactions through relay catalysis with combinations of organocatalysts with ruthenium catalysts. For example. You et al. demonstrated in 2009 that ruthenium catalyst could be compatible with Bronsted acid catalyst. They reported a practical and economical synthesis of chiral tetrahydropyrano[3,4-b]indols and tetrahydro-p-carbolines by the combination of ruthenium-catalysed olefin cross-metathesis and a chiral phosphoric acid-catalysed Friedel-Crafts alleviation reaction, as shown in Scheme 7.41. This domino reaction allowed the use of readily available materials to highly enantioselectively construct synthetically valuable polycyclic indole frameworks in enantioselectivity of up to 94% ee. 

Hydroformylation of olefins has been established as an important industrial tool for the production of aldehydes. In recent years, novel asymmetric tandem reactions have included a rhodium-catalysed enantioselective hydroformylation. In this context, in 2007 Abillard and Breit ° and Chercheja and Eilbracht independently reported a novel domino hydroformylation-aldol reaction catalysed by an achiral rhodium catalyst and L-proline catalyst (Scheme 7.49). Possibly owing to the fact that proline is hard but the rhodium catalyst is soft, the proline can be compatible with the rhodium catalyst to allow this domino reaction to be achieved. By fine adjustment of the hydroformylation rate to that of the L-proline-catalysed aldol addition, the undesired homodimerisation of the aldehyde could be avoided. As a result, by in situ hydroformylation reaction, the donor aldehyde of a... 

One final example that underscores the power of intramolecular domino reactions to achieve the stereoselective synthesis of complex nitrogen heterocycles comes from the work of Barluenga and Gonzalez, who studied the preparation of tetrahydro-quinolines by intramolecular arylation of olefins induced by the in-house developed IPy2BF4 iodonium reagent. When applied to amine 102, this method afforded the tetracyclic compound 103 by the creation of three rings and five stereocenters in an elegant, fully diastereoselective cationic cyclization cascade (Scheme 3.32) [79]. 

The palladium(II)-catalyzed olefin carbonylation reaction was first reported more than 30 years ago in studies by Stille and co-workers and James et al. The reaction of carbon monoxide with cis- and tra 5-but-2-ene in methanol in the presence of palladium(II)-chloride and copper(II)-chloride yielded threo- and eryt/zro-3-methoxy-2-methyl-butanoate, respectively. The transformation that was based on the well-known Wacker process for oxidation of ethylene into acetaldehyde in water " is now broadly defined as the Pd(II)-catalyzed oxycarbonylation of the unsaturated carbon-carbon bonds. This domino reaction includes oxypalladation of alkenes, migratory insertion of carbon monoxide, and alkoxylation. Since the development of this process, several transformations mediated by palladium(II) compounds have been described. The direct oxidative bisfunctionalization of alkenes represents a powerful transformation in the field of chemical synthesis. Palladium(II)-promoted carbonylation of alkenes in the presence of water/alcohol may lead to alkyl carboxylic acids (hydrocarboxylation), diesters [bis(aIkoxycarbonyla-tion)], (3-alkoxy carboxylic acids (alkoxy-carboxylation), or (3-alkoxy esters (alkoxy-carbonylation or alkoxy-alkoxy-carbonylation). Particularly attractive features of these multitransformation processes include the following ... 

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