Ketimines groups

The resulting product led to cyclic ketones such as Exaltone (Cyclopentadeca-none) or Dihydrocivetone (Cycloheptadecanone) in yields of 60-70%, after hydrolysis with saponification of the ketimine group and cleavage of CO2. What an ingenious move in a successful operation ... 

In a variant of the process, instead of the ketone monomer, a ketimine monomer is used to prepare a poly(ether ketimine).The ketimine polymer can be dissolved in NMP. Tbe ketimine groups in the polymer can then be hydrolyzed by means of a dilute aqueous acid solution. Hydrolysis gives back the ketone polymer that precipitates out as a fine powder. Particles of the size of 0.5-5 pm are produced by this procedure. 

The acid-catalyzed reaction of acetophenone with acyclic secondary amines results in the formation of the expected enamine and a rearrangement product. The latter product arises from the transfer of one of the amino N-alkyl groups to the cnamine s carbon to produce a ketimine (53a). 

C. Reactions not involving P=0 or P=S Groups.—Enamine phosphine oxides (45) have been prepared by the addition of amines to 1-alkynyl-phosphine oxides, and the reactions of their anions with various electrophiles have been reported. - With ketones a Wittig-type reaction leads to the formation of a/3-unsaturated ketones, in 53—70% yield, while with epoxides cyclopropyl ketimines are formed. A Diels-Alder reaction of l-phenyl-A -phospholen-l-oxide (46) with 1,4-diacetoxybutadiene has been used in the preparation of l-phenyl-benzo[/>]phosphole (47), as... 

As an alternative to oxidative deamination, decarboxylation is involved in polyamine biosynthesis and in the protection of enteric bacteria from acidic conditions. Under these conditions, the electrons used to form the ketimine are provided by decarboxylation in place of those from the a-methine group. 

Protection of the nitrogen in 4 faced the classical N- versus O-alkylation selectivity issue, which was solved by selection of the solvent system. The original protecting group, pMB, was replaced with 9-anthrylmethyl (ANM), which provided the best enantioselectivity with the newly discovered asymmetric addition to the ketimine. 

Taking Tomioka s pioneering work [8] as a precedent, we have screened 13-amino alcohols as chiral modifiers [9] in the nucleophilic addition of lithium 2-pyridinylacetylide 6 to the pMB protected ketimine 5. We were pleased to discover that when 5 was treated with a mixture prepared from 1.07 equiv each of quinine and 2-ethynylpyridine by addition of 2.13 equiv of n-BuLi in THF at -40 to -20 °C, the desired adduct 19 was obtained in 84% yield with maximum 64% ee. Soon after, we found selection of the nitrogen protective group had great influence on the outcome of the asymmetric addition and the ANM (9-anthranylmethyl)... 

Intramolecular process with rhodium catalyst has been described for the syntheses of indane, dihydroindoles, dihydrofurans, tetralins, and other polycyclic compounds. Wilkinson catalyst is efficient for the cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered to the K z-position of the imine-directing group. 

Ketimines were hydrogenated faster than aldimines, and electron-donating groups accelerated the rate of hydrogenation. The OH and RuH bonds are regenerated by hydrogen transfer to the unsaturated 16-electron Ru complex from isopropanol, generating acetone (Scheme 7.13). 

Additives may exert not only a physical but also a chemical influence on the coupling suspension long-chain aliphatic or cycloaliphatic amines RNH2, which react partially with the pigment molecules, will enhace the effect of other additives. The carbonyl function of the acetyl group is converted to a ketimine (azomethine) or, in the presence of the enol form, it reacts to form an alkylammonium enolate [5],... 

While this example of the Robinson annulation is clearly not enantioselec-tive, the same antibody converts the mero-ketone [120] into the Wieland-Miescher (WM) decalenedione product kcM = 0.086 min-1 and Km = 2.34 mM at 25°C, parameters that give an impressive ER of 3.6 x 106. Good evidence suggests that the mechanism of the reaction involves the formation of a ketimine with the e-amino group of a buried lysine residue in the antibody, as shown in Fig. 39. Most significantly, the reaction delivers the ( )-(+)-WM product in 96% ee (by polarimetry) and in 95% ee by nmr and hplc analysis for a 100 mg scale reaction. A recent report tells that this antibody is to be made commercially available at a cost of 100 for 10 mg. The realization of that objective would mark the start of a new era of application of abzymes to organic stereoselective synthesis. 

Coordination of the aluminum atom of the reducing complex was proposed to take place both to the oxygen atom of the hydroxy group and to the nitrogen atom of the amino group. The asymmetric reduction of enamine perchlorates and ketimines with menthol and bomeol chiral auxiliary reagents (50,51) presumably involves coordination of aluminum to the nitrogen atom of the substrate. 

Essentially, aU studies have used acetophenone-based iV-aryl ketimines as substrates or derivatives thereof. Some of the iV-aryl groups are easily deprotected to yield branched a-aryl primary amines, which can be further functionalized. 

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