To iminoether

Nitriles attached to thiophene behave normally. They can be converted to iminoethers and thence to amidines (78JCR(S)132, 78JCR(S)134). 

The copolymerization of the monomers listed in Table 22-6 proceeds similarly to alternating copolymers with the monomeric units given. But with the polymerization of acrylamide, the polymerization does not proceed, as in the case of initiation with strong bases, via the nitrogen atom to the j8-alanine monomeric unit [see Equation (18-9)], but via the oxygen atom to iminoether structures. 

Considerable effort has been expended in exploring the scope of ke-tenimine formation as it pertains to the introduction of 7(6)-methoxy substituents. Carrol et al. (1974) reported the facile construction of ke-tenimines derived from penicillin G and demonstrated deuterium incorporation at C-6 by base-catalyzed exchange of a related imino chloride. Workers at Sankyo later reported a method (Sugimura et al., 1976) by which an imine 145 was produced from an a-haloimino chloride (144) via base-catalyzed 1,4-elimination. The resulting imine was stereospe-cifically converted to methoxyketenimine 146 by the addition of meth-oxide anion (—78°C). Exposure to lithium methoxide at -20°C then led to iminoether 147, which was transformed to amide 148 by a new reaction with trimethylchlorosilane and I equiv of quinoline. 

WASSERMANN BORMANN Maciocydiclactamsynttwsis Ring expansion sequence of lactams by reaction with cyclic Iminoethers followed by reductive ring opening to a macrocyclic lactam. 

Cyclic enamines with an isomeric position of the double bond have been obtained by the addition of Grignard reagents to five- (78-81), six- (82-86), seven- (87-90), and thirteen- (89-91) membered lactams, whereas other medium-sized (92,93) lactams furnished amino ketones. The reaction has been extended to substituted lactams (94-98), and iminoethers (99,100). 

As part of a strategy for adding rings to system 4 the cyanide 232 was converted into the iminoether and treated with amines to give tricycle 233 (96JHC319). 

Neutral tertiary and secondary amides react with very reactive alkylating agents, such as triethyloxonium tetrafluoroborate, to give O-alkylation.63 The same reaction occurs, but more slowly, with tosylates and dimethyl sulfate. Neutralization of the resulting salt provides iminoethers. 

While screening for p-lactam antibiotics stable to p-lactamases, a strain of Streptomyces lactamdurans was found to contain several such agents which have a 6-a-methoxy group whose electronic and steric properties protect the antibiotic from enzymatic attack. Cephamycin C (29a), one of these substances, is not of commercial value, but side chain exchange has led to much more potent materials. Of the various ways of effecting this transformation, one of the more direct is to react cephamycin C with nitrous acid so that the aliphatic diazo product (29b) decomposes by secondary amide participation giving cyclic iminoether 30. The imino ether moiety solvolyzes more readily than the p-lactam to produce 7-aminocephamycinic... 

In the case of complexes such as (21) and (23) which have an extended planar ligand, a significantly higher proportion of interstrand cross-links in DNA is formed in comparison to either cis- or trans-platin.172 The steric effects of these planar ligands result in the formation of structurally unique 1,2-interstrand cross-links like those formed by cisplatin, a unique example of how steric effects may alter a nonactive lesion into an active one (Figure 13).173,174 Model studies predicted this outcome by preparation of the monofunctional models trans-[PtCl(9-ethylguanine) (NH3)(quinoline)] and comparison of substitution rates of the Pt—Cl bond by G or C mononucleotides.175 176 Interestingly, the iminoether compound (25) appears to form predominantly monofunctional adducts with DNA.177... 

The biological significance of long-lived monofunctional adducts on DNA remains to be determined, but these alone may be sufficient to kill cells if they are not repaired, which seems to be the case for the active trans iminoether complex 18 (60). Long-lived monofunctional adducts may also promote the formation of DNA-protein cross-links. 

Iminoether hydrochloride (536) was condensed with 2 mol of Meldrum s acid (421) in the presence of triethylamine in boiling chloroform overnight to give isopropylidene (2-oxo-5-methylpiperidin-6-ylidene)malonate (537) in 40% yield (86JST319). 

The reaction of EtO- with chloro compounds in ethanol is actually not an entirely satisfactory system for studying the activating effect of CN on aromatic nucleophilic substitution, because there is a tendency for CN itself to react, forming the conjugate base of iminoether, —C(OEt)=NH209. 

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