1.3- dienes three-component reactions

A related three-component reaction involving dienes employs a cobalt catalyst [67]. Unlike the above case, the third component here is a carbanion species, such... 

Sc(OTf)3-catalyzed three-component coupling reactions of aldehydes, amines, and dienes have been examined. In the presence of 10 mol % Sc(OTf)3 and magnesium sulfate, benzaldehyde was treated with aniline and Danishefsky s diene. The desired three-component reaction proceeded smoothly to afford the corresponding tetrahydropyridine derivative in 83 % yield (Eq. 9) [24b]. Under the same reaetion conditions, cyclopentadiene was used instead of Danishefsky s diene to afford the corresponding tetrahydroquinoline derivative (Eq. 10). Different combinations of aldehydes, amines, and alkenes are possible in these reactions, and afford diverse tetrahydroquinoline derivatives in high yields. 

At this point, it is interesting to note that nonconjugated dienes react first with one double bond and the rr-allyl complex is formed by migration of the other double bond (Scheme This three-component reaction can be carried out with a full range of... 

Four-Component Synthesis of Pyrrolopyridines If a primary amine were used as an input, the three-component reaction shown in Scheme 15.10 would produce an oxazole bearing a secondary amine. In other words, the so-produced adduct 24 would contain both a diene (oxazole) and a nucleophilic site (amine). Therefore, a dienophile bearing an electrophihc center would pair perfectly with the dual reactivity of 24. In practice, if an activated a,P-unsaturated carboxylic acid derivative were introduced after the three-component reaction, a sequence of N-acylation/intramolecular Diels-Alder reaction (IMDA) might occur to produce the four-component adducts. 

If a reactive dienophile was incorporated into one of the following inputs, namely, amine, aldehyde, and a-isocyanoacetamide, then the resulting oxazoles 61-63 having both the diene and dienophile functions could undergo directly the IMDA reaction. Depending on the coimectivity and the nature of the dienophile (double bond or triple bond), different products would then be produced after a sequence of three-component reaction/DA reaction/fragmentation (Figure 15.4). 

Tietze reported a domino-Knoevenagel-hetero-Diels-Alder reaction involving a three-component reaction between an a-nitroketone, formaldehyde, and an alkyl vinyl ether. In one example, a Knoevenagel condensation between ketone 105 and formaldehyde (106) yields electron-poor hetero-diene 108 that undergoes an inverse electron demand Diels-Alder reaction with ethyl vinyl ether to furnish dihydropyran 109. Tietze subsequently converted 109 into the deoxysugar (+)-forosamin. ... 

Scheme 4.19 Three-component reaction of bis-1,3-dienes, CO2, and organozinc reagents.

In addition, Zhou et al have developed diastereo- and enantioselective reductive coupling of 1,3-dienes, such as l,4-diphenylbuta-l,3-diene, with aromatic and heteroaromatic aldehydes by using ZnEt2 as the reducing agent and nickel complexes of chiral spiro phosphoramidites such as 21 (Scheme 4.21). In this case, the three-component reaction provided the... 

Scheme 4.21 Three-component reaction of 1,4-diphenylbuta-l,3-diene, aldehydes, and diethylzinc.

The nickel-catalysed three-component reaction of 1,3-enynes, aldehydes, and triethylborane was employed by several groups as a novel strategy for the synthesis of 1,3-dienes. The first asymmetric version of this methodology was developed by Jamison et al. in 2005. As shown in Scheme... 

In the context of enantioselective nickel-catalysed multicomponent reactions, many excellent results have also been achieved. For example, three-component reactions between 1,3-dienes, carbonyl compounds... 

Keywords 1,2-Diaza-1,3-dienes, amines, isocyanates, ethanol, room temperature, sequential three-component reaction, aza-Michael reaction, one-pot synthesis, functionalized 1,3,5-trisubstituted hydantoins... 

Attanasi, O. A., Bartoccini, S., Favi, G., Giorgi, G., Pemilli, F. R., and Santeusanio, S. (2012a). Powerful approach to heterocyclic skeletal diversity by sequential three-component reaction of amines, isothiocyanates, and 1,2-diaza-l,3-dienes. J. Org. Chem., 77, 1161-1167. 

When some ruthenium catalysts were used, the reaction was much more complex. An example of this variability involved the use of RuCl(CjMej)(COD) as the catalyst. This compound catalyzed the formation of a 1,3-dienyl ester instead of a simple vinyl ester (Scheme 2.98) [143]. The overall reaction can be thought of as a three-component reaction where two of the components were the same. One of the most attractive aspects of the chemistry was the observation that the reaction was highly selective for the formation of the E,E-1,4-disubstituted-1,3 -diene. 

Sehlinger A, de Espinosa LM, Meier MAR (2013) Synthesis of diverse asymmetric a,co-dienes via the Passerini three-component reaction for head-to-tail ADMET polymerization. Macromol Chem Phys 214(24) 2821-2828... 

AgOTf was reported to catalyze three-component reactions starting from aldehydes, amines, and Danishefsky s diene in water (Equation (8.22)) [47]. The reaction took place smoothly in the presence of a catalytic amount of silver triflate to afford dihydro-4-pyridones in high yields. In the case of three-component reactions with benzaldehyde, the addition of a nonionic surfactant was found to he effective. 

Scheme 2-51. Three-component reaction of dienes catalyzed by NiCl2(dppf).

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