Tandem organic reactions Synthesis

Golebiowski, A., Klopfenstein, S. R., Chen, J. J., Shao, X. Solid supported high-throughput organic synthesis of peptide 3-turn mimetics via tandem Petasis reaction/diketopiperazine formation. Tetrahedron Lett. 2000,41,4841-4844. 

The progress of tandem Heck reactions in organic synthesis [16] led to their first application in the aqueous phase. Hence, a double Heck reaction on a substrate for which /3-hydride elimination is possible results in three tricyclic products (Scheme 1) [17]. 

The Heck-Mizoroki reaction has also been heavily applied in one-pot sequential reaction sequences. The topic of sequential, domino, consecutive, or tandem catalytic reactions is a very timely subject, as at its core is efficiency, economy, and waste minimization in organic synthesis. In 2010 [59], one of us published a review of this topic which explains the current state of play and includes relevant references on the subject. However, the topic is still rather murky in terms of definitions, and this is something that we feel needs urgent attention. The Heck-Mizoroki is a very suitable transformation for inclusion in a sequential catalytic process, given that it leads to the formation of C=C units, a common functionality for further catalytic transformation. 

Odedra, A., Lush, S.-F., Liu, R.-S. (2007). Dicobaltoctacarbonyl-mediated synthesis of tricyclic 5,6-dihydropyran-2-one derivatives via tandem cycloaddition reaction between cis-epoxyaUcynes, a tethered olefin, and carbon monoxide. Journal of Organic Chemistry, 72, 567-573. 

This section summarizes the most studied organic reactions catalyzed by zeolites and mesoporous aluminosilicates useful in the synthesis of flavoring compoxmds, in perfumery, and other industrial fields. Acetalization reactions of aldehydes/ketones and the intramolecular hydroalkylation of xmsatxxrated alcohols or tandem reactions such as Claisen rearrangement and subsequent intramolecxxlar hydroxyalkylation of olefins are some of the noted reactions. 

On the basis of the examples addressed thus far, it is clear that radical reactions can accomplish manifold transformations in organic synthesis. One of the outstanding achievements of synthetic radical chemistry is the development of synthetic strategies based on controlled, tandem radical cyclizations. The efficiency of such strategies is exemplified in the substantial and elegant synthetic work of D. P. Curran and his group.54 The remainder of this chapter will address the concise total syntheses of ( )-hirsutene [( )-1]55 and ( )-A9(12)-capnellene [( )-2]56 by the Curran group. 

Dell C. P. Cycloaddition in Synthesis Contemporary Organic Synthesis 1997 4 87 Keywords natural products, metal catalyzed, asymmetric reactions, Ionic reactions, transannular reactions, tethered reactions, tandem reactions, benzo-qulnones, quinodimethanes, hefero-Dlels-Alder reactions... 

Parsons, P.J., Penkett, C.S., Shell, A.J. (1996) Tandem Reactions in Organic Synthesis Novel Strategies for Natural Product Elaboration and the Development of New Synthetic Methodology. Chemical Reviews, 96, 195-206. 

One-pot multi-bond-forming reactions are one of the ways to address the ever growing demand for efficiency in organic synthesis. Rosini and coworkers have developed (tandem) processes for the synthesis of a highly functionalized tricyclic system. The reaction is simply performed by bringing together, at room temperature, a-bromo aldehydes, ethyl nitroacetate, and chlorodimethylvinylsilane in the presence of imidazole as the base (Eq. 8.83).134... 

In recent years, the importance of aliphatic nitro compounds has greatly increased, due to the discovery of new selective transformations. These topics are discussed in the following chapters Stereoselective Henry reaction (chapter 3.3), Asymmetric Micheal additions (chapter 4.4), use of nitroalkenes as heterodienes in tandem [4+2]/[3+2] cycloadditions (chapter 8) and radical denitration (chapter 7.2). These reactions discovered in recent years constitute important tools in organic synthesis. They are discussed in more detail than the conventional reactions such as the Nef reaction, reduction to amines, synthesis of nitro sugars, alkylation and acylation (chapter 5). Concerning aromatic nitro chemistry, the preparation of substituted aromatic compounds via the SNAr reaction and nucleophilic aromatic substitution of hydrogen (VNS) are discussed (chapter 9). Preparation of heterocycles such as indoles, are covered (chapter 10). 

The reaction presented in Scheme 3.38 is involved in the novel [4+ 2] [3+ 2] tandem strategy for the use of nitroalkenes (42) in target organic synthesis (for details, see Section 3.4.4). Taking into account the great contribution of Prof. S. Denmark the in investigation of different aspects of this strategy, the latter can be classified as Denmark s approach. The principal aspects of [4+ 2]-cyclo-addition of nitro olefins were summarized in two fine reviews (99, 100). 

Reactions of Tandem [4 + 2][3 + 2] Cycloaddition of Conjugated Nitroalkenes and their Use in Organic Synthesis... 

Ley SV, Baxendale IR (2002b) New tools and concepts for modern organic synthesis. Nat Rev Drug Disc 1 573-586 Ley S V, Massi A (2000) J Comb Chem Polymer supported reagents in synthesis preparation of bicyclo[2.2.2]octane derivatives via tandem michael addition reactions and subsequent combinatorial decoration. 2 104—107 Ley SV, Schucht O, Thomas AW, Murray PJ (1999) Synthesis of the alkaloids ( )-oxomaritidine and ( )-epimaritidine using an orchestrated multi-step sequence of polymer supported reagents. J Chem Soc Perkin Trans 1 1251— 1252... 

The aldol reaction is probably one of the most important reactions in organic synthesis. In many industrially important hydroformylation processes selfcondensation of aldehydes is observed. Sometimes this consecutive reaction is favored as in the production of 2-ethyl hexanol. But synthetic applications of tandem hydroformylation/aldol reactions seem to be limited due regiose-lectivity problems of a mixed aldol reaction (Scheme 28). However, various tandem hydroformylation/intramolecular mixed aldol reactions have been described. 

Schmidt AM, Eilbracht P (2004) New Synthetic Applications of Tandem Reactions under Eiydroformylation Conditions. In Beller M, Bolm C (eds) Transition Metals for Organic Synthesis Building Blocks and Fine Chemicals. Wiley, Weinheim, p 57... 

The domino cycloaddition-iV-acyliminium ion cyclization cascade has been extensively reviewed. Tandem reactions combining Diels-Alder reactions and sigma-tropic rearrangement reactions in organic synthesis have been extensively reviewed. The tandem Diels-Alder reaction between acetylenedicarboxaldehyde and N,N -dipyrrolylmethane has been extensively studied at the RHT/3-21G and RHF/6-31G levels.The molecular mechanism of the domino Diels-Alder reaction between hexafluorobut-2-yne and A,A -dipyrrolylmethane has been studied using density functional theory. 

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