Amido nitrogen

When the migrating group is allyl, an additional concerted ([2,3] sigmatropic) pathway for rearrangement becomes available. In this an allylic shift must also occur. Nevertheless, the radical pathway is not always excluded. For example, rearrangement of ylids such as 36 (R = CHs.CO) leads to product 37 (R = CH3.CO) in which the allylic protons adjacent to the amido-nitrogen atom appear in emission (D. G. Morris, 1969). No polarization is observed in the much readier... 

In accordance with the electropositive nature of the bridgehead atoms, all di(pyridyl) substituted anions behave like amides with the electron density accumulated at the ring nitrogen atoms rather than carbanions, phosphides or arsenides. The divalent bridging atoms (N, P, As) in the related complexes should in principle be able to coordinate either one or even two further Lewis acidic metals to form heterobimetallic derivatives. According to the mesomeric structures, (Scheme 7), it can act as a 2e- or even a 4e-donor. However, theoretical calculations, supported by experiments, have shown that while in the amides (E = N) the amido nitrogen does function as... 

Methylene bridges between amido nitrogens by the reaction of methylol and amino groups on reacting molecules (Figure 19.3a)... 

In view of the importance in biochemical processes of pteridines such as folic acid, methotrexate, L-biopterin, and leucettidine <1996CHEC-II(7)679>, synthetic routes to fused pteridines continue to occupy considerable attention. Imidazo-fused pteridines have now been prepared from 3-aminopyrazine-2-carboxamides via carbodiimide intermediates. If the amido-nitrogen in the starting compound is further substituted, as in the scheme, the... 

The k pathway is three times faster in D+/D20 than in H+/H20 for la. The reverse kinetic isotope effect suggests that the rate-limiting event for the k pathway could involve protonation of an amido-nitrogen or an N-Fe bond, forming the stronger N-H bond as the weaker N-Fe bond is cleaved. The k 3 pathway is rationalized as involving pre-equilibrium peripheral protonations of the TAML macrocycle (Scheme 1). The dependence of obs on [H + ] is then given by Eq. (4), which corresponds... 

Representation of a probable conformation of N-[(2-benzylmethyIamino)-propyI] propro-nanilide hydrochloride. Note 1. End-on view of aromatic ring as shown. 2. Amido-carbonyl carbon eclipses amido-nitrogen. 3. H and Me on C-2 may be interchanged. 4. For clarity, N-Me and CH2 Ph substituents have been omitted. 

A transition metal complex such as bpyNi(COD), generalized as LjNi, reacts with NCA in a complex reaction sequence that generates a propagating species XLV whose active center is a 5-membered amido-amidate metallacyclic complex. Propagation involves a nucleophilic attack by the amido nitrogen of the amido-amidate at the C-5 carbonyl of NCA. The... 

Six-membered heterocycles (D). Both N—N bonds are included in the central ring of the molecules, which usually adopt a chair conformation. Each aluminum atom is coordinated by a negatively charged amido nitrogen atom and by an amino NR2 group of different hydrazido ligands. 

EtMg(p-L ) 2] or [ EtMg( i-L ) 2] with bridging amido nitrogen atoms (average Mg—N distances of 2.135 and 2.149 A, respectively) only two of four O atoms of the aza-15-crown-5 anion are coordinated to magnesium. 

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