Conjugation influence amides

The groups R2N and Cl can be added directly to alkenes, allenes, conjugated dienes, and alkynes, by treatment with dialkyl-V-chloroamines and acids. " These are free-radical additions, with initial attack by the R2NH- radical ion. " N-Halo amides (RCONHX) add RCONH and X to double bonds under the influence of UV light or chromous chloride. " Amines add to allenes in the presence of a palladium catalyst. ... 

The influence of solvent and additives on yield and selectivity has been examined.The conjugate addition of dimethyl cuprate in the presence of a chiral ligand, such as 144, is an example. The use of chiral ligands with Mgl2/l2 and BuaSnl gave conjugate addition products with a,(3-unsaturated amides with... 

A study of the kinetics of nitrosation of iV,iV -dimethyl-A"-cyanoguanidine in acid media (Scheme 13) [where the substrate exists as its conjugate acid (130)] has established that the mechanism of the reversible reaction is similar to that found for nitrosation of amides and ureas, rather than amines (for which attack of the nitrosating agent on the free base is usually rate limiting).The reaction, which is subject to general-base catalysis but not influenced by halide ion, involves reversible rate-limiting proton transfer in the final step and exhibits solvent deuterium isotope effects of 1.6 and... 

Bicyclic diacid template (Fig. 29.20) has also been designed and synthesized to stabilize the hydrogen-bonding pattern of a conjugated peptide in an a-helix conformation. A hexapeptide EALAKA-NH2 was attached to either the bicyclic amide or ester derivatives, and the influence of the template on the peptide conformation was evaluated in aqueous solution by using both CD and NMR. The ester-linked template enhanced the helicity of the peptide to 49% at 0°C compared with the reference hexapeptide value of 8%, while the amide-linked template was only slightly effective. 

Conjugate addition of organocuprates to , -unsaturated carbonyl compounds, including ketones, esters, and amides, are accelerated by addition of TMSCl to provide good yields of the 1,4-addition products (eq 31). The effect of additives such as HMPA, DMAP, and TMEDA have also been examined. The role of the TMSCl on 1,2- and 1,4-addition has been explored by several groups, and a recent report has been published by Lipshutz." His results appear to provide evidence that there is an interaction between the cuprate and TMSCl which influences the stereochemical outcome of these reactions. 

Open-chain secondary N-monosubstituted amides display the C=0 stretching band from 1680 to 1630 cm " Mn the solid state, and from 1700 to 1650 cm " Mn dilute solution. This band has been studied extensively, but the correlations are mainly applicable to solids (Randall et al, 1949 Thompson et al, in Clarke et al, 1949). The groups substituted on the nitrogen produce inductive and conjugation effects which influence the C=0 frequency. For example, N-chloroacetamide has its carbonyl band at 1705cm" (Gierer, 1953), while N-aryl substituted amides absorb near 1700cm" (Richards and Thompson, 1947). Jones and Sandorfy (1956) have discussed the amide I band in N,N-disubstituted amides (tertiary amides, see Table... 

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