Butanal reductive amination

The first example of this type of transformation was reported in 1974 [76]. Three catalysts were investigated, namely [Co2(CO)8], [Co(CO)g/PBu ], and [Rh6(CO)i6]. The [Co OJg/PBu ] catalyst showed activity for reductive animation using ammonia and aromatic amines. The [Rh6(CO)16] catalyst could be used for reductive animation using the more basic aliphatic amines that were found to poison the cobalt catalyst. This early report pointed out that the successful reductive animation of iso-butanal (Me2CCHO) with piperidine involves selective enamine hydrogenation, that reductive animation of cyclohexanone with isopropylamine probably involves imine hydrogenation, and that reductive amination of benzaldehyde with piperidine would presumably involve the reduction of a carbinolamine. 

D. Mandler and 1. Willner, Photosensitized NAD(P)H regeneration systems application in the reduction of butan-2-one, pyruvic, and acetoacetic acids and in the reductive amination of pyruvic and oxoglutaric acids to amino acids,... 

Pyrazines have been prepared by heating 1,2-dicarbonyl compounds with a-amino acids. Thus Rizzi (308) observed that under the conditions of the Strecker degradation, equimolar amounts of DL-valine (44) and butane-2,3-dione in refluxing bis(2-methoxyethyl) ether, diglyme, gave isobutyraldehyde, tetra-methylpyrazine (9%), and a mixture of cis- and trans-2-isopropyl-4,5-dimethyl-3-oxazoline (4%). He proposed a reductive amination mechanism in which butane-23-dione was converted to 2-aminobutan-3-one which underwent self-condensation to the pyrazine. Tetramethylpyrazine was also prepared when the same reactants were heated in dimethylformamide at 123° for 5 hours (and other pyrazines prepared similarly) (308a). 

In a reductive amination/deprotection/Davis-Beirut reaction process, o-nitrobenzaldehydes 147 and 4-(tritylthio)butan-l-amine 148 combined to form a pair of l,3-thiazepino-2H-indazoles 149. Subsequent S-oxidation gave the corresponding sulfones.The oxygen analog 150 was prepared by using 4-aminobutan-l-ol instead of 148 (14JOC6939). 

The amino groups of ovomucoid, lysozyme, and ovotransferrin were alkylated extensively (40-100%) with various carbonyl reagents in the presence of sodium borohydride. Monosubstitution was observed with acetone, cyclopentanone, cyclohexanone, and benzaldehyde, while 20-50% disubstitution was observed with 1-butanal and nearly 100% disubstitution was observed with formaldehyde. The methylated and isopropylated derivatives of all three proteins were soluble and retained almost full biochemical activities. Recently amine boranes have been shown to be possible alternative reducing agents for reductive alkylation... 

Ether solutions based on TAA salts are not reduced on noble metal electrodes. The major cathodic reaction of these solutions involves the cation reduction to trialkyl amine, alkane, and alkene (which are the stable disproportion products of the alkyl radical formed by the electron transfer to the cation) [3], Electrolysis of ethers such as THF or DME containing TBAP, formed in the catholyte tributyl amine, butane and butene, were unambiguously identified by NMR and GCMS analysis [3], In the presence of water (several hundred ppm and more), the electrolysis products were found to be tributyl amine and butene (butane was not detected) [3], The potential of this reduction reaction is higher than that of the dry solution, and it is clear that the initial electroactive species in this case is the... 

Cyclam and cyclen can be prepared by reduction of bisaminals formed by reaction of glyoxal with [Ni(2,3,2-tet)]2+ (8) or [Ni(2,2,2-tet)]2+, respectively.27 Aminals formed by these amines with glyoxal (9), or butane-2,4-dione, react with nucleophiles Br(CH2)2j3Br to form aminals of the [12], [13] or [14]- (10) membered cyclic tetraamines, which release the amines when reacted with dilute add.28... 

Condensation of 2-acetylthiophen with glyoxylic acid in the presence of a secondary amine gave compounds of the type (164a). Products from the reductive electrochemical dimerization of 2-acetyIthiophens, such as 2,3-di-(2-thienyl)butane-2,3-diol, have been isolated and identified. ... 

A catalyst for the selective cyclodimerization of butadiene to 4-vinylcyclo-hexene can be generated by the reduction of [Fe(NO)2Cl], with metal carbonyls or electrochemically. Addition of cyclic amines to the isoprene dimerization catalyst [NiCl2(PPhs)2]-NaBH4-H20 enhances the formation of cyclic dimers the product distribution has been correlated with an electronic and structural properties of the amine. [Ni P(n-OC6H4R)3 J (R = Ph or SiMes) catalyses the selective (95 %) dimerization of butadirae to cyclo-octa-1,5-diene the catalysts appear to operate via two active centres, probably the Ni and P atoms. When solutions of (44) are allowed to stand and then treated with HCl or Brj signficant amounts of [1,1,3,3- H4]- and [2,2,3,3- H4]-butane are produced in addition to the anticipated [1,1,4,4- H4]-isomer. This would seem to indicate that there is an equilibrium (14) and in keeping with this (44)... 

Kagan HB, Langlois N, Dang TP. Reduction asymetrique catalysee par des complexes de metaux de transition IV. syn-these d amines chirales au moyen d un complexe de rhodium et d isopropylidene dihydroxy-2,3 bis (diphenylphosphino)-l,4 butane (diop). J. Org. Chem. 1975 90(3) 353-365. 

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