Of imines and related compounds

Arene(tricarbonyl)chromium complexes, 19 Nickel boride, 197 to trans-alkenes Chromium(II) sulfate, 84 of anhydrides to lactones Tetrachlorotris[bis(l,4-diphenyl-phosphine)butane]diruthenium, 288 of aromatic rings Palladium catalysts, 230 Raney nickel, 265 Sodium borohydride-1,3-Dicyano-benzene, 279 of aryl halides to arenes Palladium on carbon, 230 of benzyl ethers to alcohols Palladium catalysts, 230 of carboxylic acids to aldehydes Vilsmeier reagent, 341 of epoxides to alcohols Samarium(II) iodide, 270 Sodium hydride-Sodium /-amyloxide-Nickel(II) chloride, 281 Sodium hydride-Sodium /-amyloxide-Zinc chloride, 281 of esters to alcohols Sodium borohydride, 278 of imines and related compounds Arene(tricarbonyl)chromium complexes, 19... 

It has been shown that lanthanide triflates are excellent catalysts for the catalytic activation of imine and related compounds, while most Lewis acids are decomposed or deactivated in the presence of basic nitrogen atoms. For example, (a) Kobayashi S, Bu-sujima T, Nagayama S (1998) J Chem Soc, Chem Commun 19 (b) Kobayashi S, Nagayama S (1997) J Am Chem Soc 119 10,049 (c) Kobayashi S.Akiyama R, Kawamura M, Ishitani H (1997) Chem Lett 1039 (d) Kobayashi S, Ishitani H, Ueno M (1997) Synlett 115... 

Hydrogenation and Transfer Hydrogenation of Imines and Related Compounds... 

Chiral a-branched amines are common substructures within biologically active materials and hence attract broad interest, particularly in the areas of synthetic methodology, bioorganic and medicinal chemistry and natural product synthesis. Additions of carbon fragments to C=N bonds of imines and related compounds build up the carbon framework in the same way as asymmetric induction, so this approach is one of the more attractive entries to chiral amines. ... 

Intramolecular addition of trialkylboranes to imines and related compounds have been reported and the main results are part of review articles [94, 95]. Addition of ethyl radicals generated from Et3B to aldimines affords the desired addition product in fair to good yield but low diaster control (Scheme 40, Eq. 40a) [96]. Similar reactions with aldoxime ethers [97], aldehyde hydrazones [97], and N-sulfonylaldimines [98] are reported. Radical addition to ketimines has been recently reported (Eq. 40b) [99]. Addition of triethylborane to 2H-azirine-3-carboxylate derivatives is reported [100]. Very recently, Somfai has extended this reaction to the addition of different alkyl radicals generated from trialkylboranes to a chiral ester of 2ff-azirine-3-carboxylate under Lewis acid activation with CuCl (Eq. 40c) [101]. 

Radical addition of organoboranes to imines and related compounds is a promising alternative to the use of classical organometallic compound (see... 

Aza-analogues of oxygen compounds frequently show related reactivity patterns, and this is certainly seen in a comparison of the chemistry of imines and carbonyl compounds. For example, 1,3-diimines are readily deprotonated to yield the 1,3-diketonate analogues. The most frequent consequence of this is that reactions which are expected to yield 1,3-diimine complexes often lead to those of the deprotonated species. This is seen in the formation of the gold(m) complex of a deprotonated macrocycle in the reaction of 1,2-diaminoethane with 2,4-pentanedione in the presence of Na[AuCl4] (Fig. 5-4). The exact sequence of events in this reaction is not known, but note that the product is a square-planar gold(in) complex of the doubly-deprotonated macrocycle, rather than a gold(i) species ... 

Imines and related compounds containing a carbon-nitrogen double bond C=N (hydrazones, acylhydrazones, oximes) present the very attractive feature of being double dynamic entities capable of undergoing both ... 

In conclusion, although it is fair to say that the mechanism of the antitumor activity of ellipticines and related compounds remains unproved, metabolic activation of an ellipticine to a quinone imine or related species of high elec-... 

The nucleophilic addition reactions of enolates to imines and related compounds (the so-called Mannich-type reactions, equation 39) are important tools in organic synthesis and a variety of electrophiles have been used to obtain the resulting nitrogen-containing... 

The reaction of a wide range of imines and other compounds containing the C=N moiety with 14 leads to the formation of azacyclopentenones, e.g. 337 (equation 100). Certain of the product heterocycles undergo oxidative dimerization Moreover, related five-membered ring systems result from analogous reactions of 14 with l-(r-pyrrolidinyl) acenaphthylene and thiazoline-5-thiones. ... 

This chapter concerns the net conversion of a C =X ir-bond (X = O and N) to various three-membered ring heterocycles. The most common such process is the conversion of an aldehyde or ketone to a homologous epoxide. These reactions will be discussed along with the analogous process which takes place on imines and related compounds. Additionally, methods to effect the addition of elements other than carbon across either unsaturated system will considered. The synthesis of thiiranes by the addition of carbon across the C—S rr-bond is the subject of a recent comprehensive review and will not be covered here. 

Scheme 2.133 Trifluoromethylation of nitrogen electrophiles, imines, and related compounds (TMS = trimethylsilyl) [80-84].

Addition of carbon-centered radicals to imines and related compounds (heterocyclizations) 01T5461. 

Addition of Carbon-Centered Radicals to Imines and Related Compounds," Friestad. G.K. Tetrahedron, 2001, 57, 5461. 

Methyl migration has been noted in the hydrogenolysis of (515) and related compounds over palladium and platinum catalysts. Cleavage of the three-membered ring occurs on catalytic hydrogenation of prazepam (516X in contrast to electrolysis which reduces only the imine function. ... 

Propargylation/allenylation of carbonyls, imines, and related compounds... 

The asymmetric addition of phosphorus nucleophiles to imines provides direct access to phosphorus-containing chiral amines. While this chemistry is dominated by the use of phosphites and related compounds, a report by Duan outlines a successful protocol for the asymmetric addition of secondary phosphines to imines (Scheme 4.30) [81]. The reaction was catalyzed by a chiral palladium compound comprised of a palladium(II) center Ugated by a resolved pincer compound. A range of aryl and heteroaryl imines as well as several secondary phosphines were successfully used in this reaction. To aid in the isolation of the phosphines, the authors added elanental sulfur at the end of the P—C bond-fomung reaction. This chenustry provides access to a range of chiral N,P Ugands for metal centers that were previously challenging to prepare and isolate. 

As mentioned above, a range of enantioselective transformations have been established using chiral phosphoric acids via the activation of imines and related nitrogen-substituted substrates. In contrast, the activation of carbonyl compounds, including a,P-unsaturated carbonyl compounds, by chiral phosphoric acids has been limited. In 2008, Zhou, He, and coworkers achieved the asymmetric Friedel-Crafts alkylation reaction of indole derivatives with 1,3-diaryl a,p-unsaturated... 

FIGURE 17 11 Imine formation between the aldehyde function of 11 as retinal and an ammo group of a protein (opsin) is involved in the chemistry of vision The numbering scheme in retinal is specifically developed for carotenes and related compounds... 

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