Cyclo-addition reactions multicomponent

Among multicomponent cyclo-addition reactions, the [2 - 2 + 2] case is by far the most common, and the supra-supra-supra mode is encountered most frequently, Equations (6.77), (6.78). The [ 2g + 2, interaction, also a... 

Metal-catalysed multicomponent cyclo-addition reactions are not considered here because the interpretation of the mechanisms of these reactions is still highly controversial. 

H-pyrane] derivatives in the presence of isatins, malononitrile, and acetylacetone/ethyl 3-oxobutanoate [103]. Yan and coworkers showed in 2012 that chiral tertiary amine-thiourea (158) derived from quinine can catalyze a three-component reaction between isatins 118, malononitrile (119), and a-phenyl-isocyanoacetate (217) (Scheme 2.75) [104]. The process affords dihydropyrryl-spirooxindoles 218 and involves an initial Knoevenagel condensation of 118 and 119 followed by the nucleophilic anion attack of 217 (see the key transition state intermediate on Scheme 2.75). Final intramolecular cyclo-addition affords the expected compounds where H bond interactions are supposed to direct the attack of isocyanate anion and, consequently, contfol the enantioselectivity. One year later, Xu s group used a bifunctional cinchona-based squaramide to catalyze multicomponent cascade reaction to synthesize spiro[pyrrolidin-3,2 -oxindoles] via 1,3-proton shift and [3h-2]... 

Certain apparently low order cyclo-additions could equally well be regarded as disguised multicomponent processes. Consider, for example, reaction (6.83) the transition state could be likened to the [ 2j + 4s] cyclo-addition between a pentadienyl cation and an olefin, (56). The alternative [ 2s + 2j + a s jt2s + it2s] pathway (57) seems equally attractive. Several other reactions have this sort of duality in interpretation,... 

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See also in sourсe #XX -- [ , , ]

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