Curtis reaction

Reactions of selected metal complexes of multidentate amines with formaldehyde and a range of carbon acids (such as nitroethane) have led to ring-closure reactions to yield a series of three-dimensional cage molecules (see Chapter 3). Condensations of this type may also be used to produce two-dimensional macrocycles (Comba et al., 1986) - see [2.20], In such cases, it appears that imine intermediates are initially produced by condensation of the amines with formaldehyde as in the Curtis reaction. This is followed by attack of the conjugate base of the carbon acid on an imine carbon. The resulting bound (new) carbon acid then reacts with a second imine in a cis site to yield chelate ring formation. 

One of the most spectacular and useful template reactions is the Curtis reaction , in which a new chelate ring is formed as the result of an aldol condensation between a methylene ketone or inline and an imine salt. The initial example of this reaction was the formation of a macrocyclic nickel(II) complex from tris(l,2-diaminoethane)nickel(II) perchlorate and acetone (equation 53).182 The reaction has been developed by Curtis and numerous other workers and has been reviewed.183 In mechanistic terms there is some circumstantial evidence to suggest that the nucleophile is an uncoordinated aoetonyl carbanion which adds to a coordinated imine to yield a coordinated amino ketone (equation 54). If such a mechanism operates then the template effect is largely, if not wholly, thermodynamic in nature, as described for imine formation. Such a view is supported by the fact that the free macrocycle salts can be produced by acid catalysis alone. However, this fact does not... 

The Curtis Reaction Lysergic Acid Hydrazine Lysergic Acid Azide and Lysergic Acid Amides... 

Other examples of template cyclization reactions leading to macrocycles with amine double bonds that can be reduced to the fully saturated systems will be discussed later. Often, without the template ion, small 1 1 cyclizations take place. In the case of the Curtis reaction, a seven-membered ring was formed without the template ion (Montecatini, 1968). Ethylenediamine condensed with mesityl oxide or with other a,/3-unsaturated ketones to give tetrahydro-l,4-diazepines without the template ion (Elguero et al., 1969 Guareshi, 1894 Mushkalo and Shokol, 1960). However, in the case of reactions of rigid arylideneacetone or benzylideneacetophenone with ethyl-... 

The Reaction of a Simple Aldehyde, Ketone, or a,/3-Unsaturated Carbonyl Compound and a Diamine (Curtis Reaction)... 

N. F. Curtis ( Curtis reaction—first to report the aza-crown macrocycles)... 

Cuprate, hexanitrito-stereochemistry, 53 Cuprate, tetrachloro-structure, 53 Curie temperature, 258 Curie-Weiss law, 258 Curtis reaction... 

Aldol condensation reactions and/or Curtis reactions arc most often used to give C-C bonds. The role of the metal ion is reduced to bringing the fimctional groups into close proximity, to favour their interaction. Another conunon procediue is the Glaser reaction, which enables the coupling of terminal alkynes and inserting the... 

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