Domino metathesis reactions

Within this chapter, two sections are devoted to rhodium and ruthenium. The two main procedures using rhodium are first, the formation of 1,3-dipoles from diazocompounds followed by a 1,3-dipolar cycloaddition [10] and second, hy-droformylation [11], The ruthenium-catalyzed domino reactions are mostly based on metathesis [12], with the overwhelming use of Grubbs I and Grubbs 11 catalysts. 

Grigg and coworkers developed bimetallic domino reactions such as the electro-chemically driven Pd/Cr Nozaki-Hiyama-Kishi reaction [69], the Pd/In Barbier-type allylation [70], Heck/Tsuji-Trost reaction/1,3 dipolar cycloaddition [71], the Heck reaction/metathesis [72], and several other processes [73-75]. A first example for an anion capture approach, which was performed on solid phase, is the reaction of 6/1-134 and 6/1-135 in the presence of CO and piperidine to give 6/1-136. Liberation from solid phase was achieved with HF, leading to 6/1-137 (Scheme 6/1.30) [76]. 

A combination of a metathesis and a Diels-Alder reaction was published by North and coworkers [263]. However, this is not a true domino reaction, as the dienophile (e. g., maleic anhydride) was added after the in situ formation of the his-butadiene 6/3-89 from the fois-alkyne 6/3-88 and ethylene. The final product is the fois-cycloadduct 6/3-90, which was obtained in 34% yield. Using styrene as an un-symmetrical alkene instead of ethylene, the mono-cycloadduct 6/3-91 was formed as a mixture of double-bond isomers, in 38% yield (Scheme 6/3.26). 

The Tebbe reagent reacts with some alkenes. The tricyclo[5.3.0.0] ring 207 was obtained nearly quantitatively by domino alkene metathesis and carbonyl alkenation of the norbomene-type ester 205 with the Tebbe reagent. This interesting reaction to give the intermediate 206 can be explained by the kinetic preference of the Tebbe reagent for the strained double bond over the ester. Alkenation of the ester in 206 produces 207. Capnellene (208) has been synthesized by applying this reaction as a key reaction [65],... 

We have found that a combination of intermolecular and intramolecular domino enyne metathesis reactions is also feasible [122]. Reaction between 1,6-heptadiynes 69-72 and allyltrimethylsilane promoted by 2 gave triene cycloadducts 73-76 in moderate-to-good yields (Scheme 22). 

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. 

Also a number of domino-reactions starting with a metathesis reaction, followed by another metathesis reaction, a Heck reaction, a pericyclic reaction or a hydrogenation have been reported. ... 

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). " ... 

In our previous book on domino reactions [4h], we have classified domino reactions according to the mechanism of the different steps. This organizing principal will also be used in this book, and you will find chapters about transition metal catalysis including carbonylation, metathesis and CH-activation, nucleophiHc substitutions, radical reactions, pericyclic reactions, Michael reactions, aldol reactions, oxidations, and reductions. 

Domino reactions consisting of a cross-metathesis (CM) and an RCM step were used to construct macrocycles in a one-pot manner [5]. Thus, the macrocydic... 

As illustrated by the schemes above, metathesis reactions in domino processes have swiftly become an established tool in modern organic synthesis. Especially, RRM and domino dienyne metathesis have found extensive uses and will surely continue to catch the attention of synthetic chemists as elegant and atom-economic transformations that allow a quick enhancement of molecular complexity. Next to combinations of metathesis events only, the incorporation of non-metathesis steps into true domino processes has advanced to a remarkable level and will certainly provide even more opportunities in the years to come. 

A tandem (domino) cross-metathesis reaction between an enyne and 3 equivalents of a conjugated alkene proceeds in dichloromethane at 40 °C for 12 h with a high yield in the presence of the same ruthenium-carbene flve-membered ring compound 8.53, as shown in Eq. (8.21) [54, 55]. 

Scheme 7.41 Domino cross-metathesis-Friedel-Crafts reaction catalysed by chiral phosphoric acid catalysis and ruthenium catalysis.

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. 

Grigg et al. reported a successful four-component domino reaction for the synthesis of functionalized dienes 316 from aryl iodides, allyl amine derivative, allene, and carbon monoxide [110] (Scheme 6.83). Carbon monoxide could insert into the C—Pd bond of arylpalladium(II) iodides to generate a carbonylpalladium species, which is followed by allenylation to form n-allylpalladium species. Finally, the attack of the nitrogen nucleophile produces the product observed. The products of this domino multicomponent reaction could be subjected efficiently to ring-closing metathesis in the presence of Grubbs second-generation catalyst. 

In addition, Kongkathip et al. reported on a synthesis of Tamiflu via a metal-mediated domino reaction and ringclosing metathesis. ... 

---