Dummy ligand

The recognition of the importance of duster structure has resulted in a new understanding of the role of a dummy ligand (Y) in the diemistry of mixed cuprates MeCu(Y)Li [145]. As shown in Sdieme 10.15 for the case of Y = alkynyl the 

336 I 70 Mecho ls r s of Copper-medloted kdditiO o -id (Abitit(Atio -i Reoctio M 

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We came up with the idea of using a dummy ligand, as shown in Scheme 1.23 [34]. Reaction of dimethylzinc with our chiral modifier (amino-alcohol) 46 provided the methylzinc complex 62, which was subsequently reacted with 1 equiv of MeOH, to form chiral zinc alkoxide 63, generating a total of 2 moles of methane. Addition of lithium acetylide to 63 would generate an ate complex 64. The ate complex 64 should exist in equilibrium with the monomeric zincate 65 and the dimer 66. However, we expected that the monomer ate complex 64 and the mono-... 

Although both boronates and alanates react with allylic bromides, aldehydes and C02 to afford allenic products in satisfactory yield, the alanates are more efficient in additions to ketones (Table 9.14). Boronate reagents do not require a B-C alkyl migration for their preparation. Thus the starting acetylene possesses the structural elements of the product. Additionally, the issue of dummy ligands is irrelevant. 

For typical uses of these groups as dummy ligands see (a) B. H. Lipshutz, in OrganometaUics in Synthesis A Manual, Schlosser,... 

Scheme 10.1S. Dummy ligands selective transfer of the methyl (or alkyl, alkenyl, aryl) group in preference to transfer of the alkynyl group.

Two artificial compound libraries were chosen as compound mixtures, of which library 1 was composed only of dummy ligands (acetanilide, amitryptiline, benzoic acid, (+)-bicuculline, 4-chloraniline, 2,3-dichloraniline, methylbenzoate, phenol, tramadol see Fig. 7.11), whereas library 2 contained, in addition to these compounds, naloxone, a known //-opioid receptor ligand. 

This procedure is an illustration of the use of mixed, higher order (H.O.) cyanocuprates containing a non-transferable or "dummy" ligand for epoxide opening.8 H.O. cuprates of general stoichiometry RT(2-th enyl)Cu(CN)Li2 can also be used to... 

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