Nucleophilic Addition to Coordinated Carbonyls

A wide range of nucleophiles has been shown to attack coordinated carbonyl compounds. The products depend upon the fate of the tetrahedral hydroxy intermediate formed. In the reaction of carbonyl compounds and amines the loss of water results in the formation of imines, and this methodology has widespread synthetic application. A novel sexidentate macrocyclic ligand (26) has been prepared by template methods. The formation of the hydrazone from hydrazine and 

Hole-size effects are also of importance in the metal-directed self-condensation of 2-aminobenzaldehyde condensation in the presence of [Mo2(02CCF3)4(PR3)2] in ethanol results in the formation of complexes of (27). The ring size is controlled by the addition of ethanol, and complexes with varying numbers of ethoxy groups (0-2) are obtained with various metals.  

A particularly spectacular example of a metal-controlled reaction is seen in the reactions of 1,2-diaminobenzene with manganese(II) chloride in acetone solution. In the absence of air the expected macrocycle (28) is formed, but under an atmosphere of oxygen the novel compound (29) is obtained. Various intermediates in the formation of (29) were isolated, and a detailed mechanism proposed.  

The hydrolysis of chelated amino acid esters, H2NCHRCO2R, is known to be accelerated by metal ions, most notably cobalt(III). Dramatic enhancements are also observed with copper(II). Mechanistic studies of the hydrolysis of amino acid esters with copper(II) complexes of glycyl-DL-valine and dien (H2HCH2CH2NHCH2CH2NH2) have been reported/ The hydrolysis of benzyl-penicillin (30) by copper(II) salts to give (31) has been further investigated, and it is proposed that the key step involves intramolecular attack by metal-coordinated hydroxide in an intermediate of type (32). 

The hydrolysis of the monocarboxylate and phosphonate esters (33) derived from cyclam is enhanced by copper(II), which initially coordinates to the macrocy-clic ligand. In the case of the phosphonate, at pH values above 11.5 the attack is 

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