Copper template synthesis

Our template synthesis of knots implies that the target molecules are obtained as cationic dicopper(I) complexes. Therefore we considered the possibility of interconverting both enantiomers into a pair of diastereomeric salts [137, 138] by combining them with an optically active anion. Binaphthyl phosphate (BNP") [139] drew our attention because its chirality arises from the binaphthyl core, which is twisted. This helical structure is of the same type as that of die copper double helix, precursor of the knot. Besides, both compounds are aromatic and, thus, we could expect some potentially helpful stacking interactions [87],... 

Template reactions between malonaldehydes and diamines in the presence of copper(II), nickel(II) or cobalt(II) salts yield neutral macrocyclic complexes (equation 15).99-102 Both aliphatic102 and aromatic101 diamines can be used. In certain cases, non-macrocyclic intermediates can be isolated and subsequently converted into unsymmetrical macrocyclic complexes by reaction with a different diamine (Scheme ll).101 These methods are more versatile and more convenient than an earlier template reaction in which propynal replaces the malonaldehyde (equation 16).103 This latter method can also be used for the non-template synthesis of the macrocyclic ligand in relatively poor yield. A further variation on this reaction type allows the use of an enol ether (vinylogous ester), which provides more flexibility with respect to substituents (equation 17).104 The approach illustrated in equation (15), and Scheme 11 can be extended to include reactions of (3-diketones. The benzodiazepines, which result from reaction between 1,2-diaminobenzenes and (3-diketones, can also serve as precursors in the metal template reaction (Scheme 12).101 105 106 The macrocyclic complex product (46) in this sequence, being unsubstituted on the meso carbon atom, has been shown to undergo an electrochemical oxidative dimerization (equation 18).107... 

The template synthesis (3.256) led to only one complex 818 [616], which was also obtained by a chemical method from the same components and copper acetate under boiling of the reaction mixture ... 

Bauerle and coworkers have adapted the Cu+ template (48) approach to [2]cate-nane synthesis using an intermediate platinum diacetylide linkage to macrocyclize each of the two rings (49, Scheme 10.9) [38], Oxidation of the platinum centers in the macrocyclic rings of SO with I2 induces reductive elimination of the two acetylides to form the 1,3-butadiyne linked macrocycles (51). Unfortunately, the authors could not remove the copper template in this example, likely as a result of steric congestion about the metal ion in the interlocked product. 

Complexation of metal ions and subsequent incorporation of the resulting metal complex into the oxide matrix during surfactant-templated synthesis prevents aggregation and leads to a homogeneous distribution of metal centers in the mesostructure. Copper- and vanadium-substituted mesoporous silicas were prepared in this way [107,108], Such materials have great potential in the field of catalysis. 

Figure 2.21. Copper(I)-templated synthesis of [2]-catenate 56 and its demetallation to the corresponding [2]-caten<2nd 57.

Figure 2.30. Copper(I)-templated synthesis of Cu(I)-complexed [3]-rotaxane 86 and compartmental [5]-rotaxane 87, bearing free-base porphyrins as stoppers.

Figure 2.37. Copper(I)-templated synthesis of a Zn(II)/Au(III) bis-porphyrin-stoppered [2]-rotaxane as its Cu(I) complex (102) and as free [2]-rotaxane (107).

With an excess of [CuAN4](C104)2, the first binuclear compound with a possibly delocalized bond of Cu(I)/Cu(II) was also prepared [197]. A detailed template synthesis of the binuclear copper(II) complexes of macrobicyclic imBT ligand with a regular cavity and an imbistrpn ligand with an expanded cavity (Scheme 93) is described in Ref 198. 

Figure 35 Copper (I)-templated synthesis of metal-complexed [2]-rotaxane (105) bearing...

Figure 51 Principle of transition metal-templated synthesis of a [3]-rotaxane, from two chelating macrocycles (B) and a bis-chelate-containing molecular thread (A) functionalized with reactive end groups X (same conventions as in Figure 43). (ii) Threading step, affording prerotaxane (C) construction of the porphyrin stoppers providing copper(I)-complexed [3]-rotaxane (D).

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