Amines with imino ethers

The formation of tluorinated Q -hydroxy-jS-imino esters (180) by treatment of fluorinated imino ethers (179) with lithium 2,2,6,6-tetramethylpiperidide has been reported. A possible explanation for this interesting intramolecular rearrangement is proposed in Scheme 64. Acyclic imides derived from primary benzylic amines and amino acid esters have been found to undergo a novel nitrogen to carbon acyl migration via a base-generated carbanion to yield the corresponding a-amino... 

Reduction of a-imino ketones 52, prepared from 1,2-diketones 51 and 1 equiv of an amine, with sodium in ether, followed by treatment with ethyl chloroformate or... 

Resin-bound amines can be converted into imines [710,711] or enamines by reaction with carbonyl compounds (Entries 6 and 7, Table 3.39). Resin-bound enamines have also been prepared by Michael addition of resin-bound secondary amines to acceptor-substituted alkynes [712], by Hg(II)-catalyzed addition of resin-bound secondary amines to unactivated alkynes [713], by addition of C-nucleophiles to resin-bound imino ethers [714], and by chemical modification of other resin-bound enamines [712,713,715], Acceptor-substituted enamines ( push-pull alkenes) are not always susceptible to hydrolytic cleavage by TFA alone and might require aqueous acids to undergo hydrolysis [716]. 

A very wide range of nucleophiles other than water and alcohols has been shown to react with co-ordinated nitriles (Fig. 4-15). The reaction with ammonia or amines is a particularly convenient method for the preparation of amidine complexes. Specific examples of these reactions are presented in Fig. 4-16, illustrating the formation of amide, imino-ether or amidine complexes. 

Heterocyclic imino ethers are readily made in 40-80% yields by heating a heterocyclic amine with triethyl orthoformate in the presence of p-toluenesulfonic acid. When these ethers arc treated with the monoanion of TOSMIC they are converted into I-heteroaryl substituted 4-tosylimidazolcs (4) in high yields (75-90%) (Scheme 4.2.1) f6]. 

Imino ether hydrochlorides can be reduced to amines in good yields at lead cathodes in aqueous sulfuric acid [159]. Cathodic reduction of nitriles in ethanolic sulfuric acid should be a useful procedure, therefore, with the first step in situ formation of an imino ether salt. 

Allylic transposition. Transformation of allylic alcohols into derivatives of amines and thiols is accomplished by treatment of their imino ethers and thionocarbamates with (MeCNjjPdClj. 

Addition of Alcohols, Water, and Amines. In general, additions to nitriles resemble additions to carbonyl groups with the exception that the primary addition products of simple molecules such as alcohols, water, and ammonia result in the formation of somewhat more stable compounds. Alcohols, for example, react with nitriles in the presence of an acidic catalyst to form salts of imino ethers ... 

Curing of EP2 provides a fuUy cured network in the bulk and a relatively low cooperative mobility (Tg=177°C). The molecular mobility of EP2 is similar on SSI and SS2 but significantly lower than in the bulk due to a lower degree of cyano conversion. Correspondingly, the layers contain a lower density of imino ether-like crosslinks while the densities of amine- and ether-like crosslinks are like those in the bulk. Only in EP2 on SSI and SS2 is a second phase with increased mobility present just after curing. 

Halogenation of Lactams. Selective and high yielding iodination and bromination of lactams occurs with Iodine or Bromine, respectively, in the presence of TMS-I and a tertiary amine base (eq 24). The proposed reaction mechanism involves intermediacy of the silyl imino ether. 

Secondary and tertiary amides react with (C2H )30 BF4 to form imino ether fluoborates which are reducible with NaBH4 to the amine in almost quantitative yields. Th is method is useful when the molecule contains other reducible groups, such that LiAlH4or B2H are not satisfactory. 

Enamines of cyclohexylamine have been enantioselectively cyclized to bicyclo[3.3.1] nonanedione systems, using acryloyl chloride and chiral pyrrolidine catalysis. Enantio-pure A-sulflnylimines have been used in asymmetric synthesis of isoquinolone alkaloids, and a stereocontrolled synthesis of 3,4,5,6-tetrahydropyrimidine-based amino acids from imino ethers has been reported. Diastereoselective additions of chiral acetals of (2-lithiophenyl)acetaldehyde to arylimines have been used in an asymmetric synthesis of 1-aryltetrahydroisoquinolines. " Organolithiums react with chiral imines, in the presence of Lewis acids or bases, to give amines in up to 100% de. Diastereoselective additions of copper reagents to imines derived from (5)-l-phenylethylamine have been reported. 

Polyureas. Polyureas involve the combination of novel MDI polymers and either amine or imino-functional poly ether polyols. The resin systems can be reinforced with milled glass fibers, flaked glass, Wollastanite, or treated mica, depending on the compound requirements as too processability or final product. 

When W-aceCyl-protected sugar amines were under investigation the A -acetyl group was observed to undergo transformation to the O-benzyl imidate in competition with OH benzylation (eq 3). It appears for best yields at least 1 equiv of reagent per OH and NAc group is needed, and subsequent hydrolysis and reacetylation of the amine are necessary to obtain are the originally desired material. Similar problems were encountered with the morpholine derived lactams (eq 4), where mixed products were obtained, but with p-lactams with yV-amide protection (eq 5), t -benzylation with benzyl trichloroacetimidate proceeded smoothly. BTCA has recently been used to convert diketopiperazines into their bis-benzyl imino ethers. ... 

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