Amines from hydrazones

Platinum oxide Amines from hydrazones s. 3, 39 PtO, C NNHR -> CHNH2... 

Sodium/alcohol s. under H2C(CNjCOOCg/fs Zinc/acetic acid Amines from hydrazones s. 21,53... 

Sulfonic acid amides from sulfonic acid hydrazides Amines from hydrazones... 

Aldehyde-containing macromolecules will react spontaneously with hydrazide compounds to form hydrazone linkages. The hydrazone bond is a form of Schiff base that is more stable than the Schiff base formed from the interaction of an aldehyde and an amine. The hydrazone, however, may be reduced and further stabilized by the same reductants utilized for reductive amination purposes (Chapter 3, Section 4.8). The addition of sodium cyanoborohydride to a hydrazide-aldehyde reaction drives the equilibrium toward formation of a stable covalent complex. Mallia (1992) found that adipic acid dihydrazide derivatization of periodate-oxidized dextran (containing multiple formyl functionalities) proceeds with much greater yield when sodium cyanoborohydride is present. 

Primary amines form Schiff bases, (CH )2C=NR. Ammonia induces an aldol condensation followed by 1,4-addition of ammonia to produce diacetone amine (from mesityl oxide), 4-amino-4-methyl-2-pentanone [625-04-7], (CH3)2C(NH2)CH2COCH3, and triacetone amine (from phorone), 2,2,6,6-tetramethyl-4-piperidinone [826-36-8]. Hydroxylamine forms the oxime and hydrazine compounds (RNHNHJ form hydrazones (RNHN=C(CH3)2). Acetone and nitrous acid give the isonitroso compound which is the monoxime of pymvaldehyde [306-44-5], CH COCH=NOH. 

Pyridazinones were obtained from an attempted Fischer indolization of a cyclopentanone phenylhydrazone [85CI(L)697], from hydrazones of unsaturated 1,4-keto esters (87H2101) or from 3-arylhydrazones of 4-(4-methoxyphenyOglutaconic anhydride in the presence of seconday amines [83IJC(B)512]. Pyridazines 6 can be synthesized from 2-phenylhydrazones of 1,2,3-tricarbonyl compounds and phosphacumulenylides (80TL2939 85CB1709). 

Kenner and Knight point out that hydrazones are formed from free hydrazine bases, whereas hydrazine salts, such as phenylhydrazine acetate, yield osazones. It is emphasized that salt formation greatly favors such reactions as the production of amines from hydrazo compounds, a reaction which is represented as follows. The cation therefore... 

Chiral hydrazines, supported on Merri-field resin, were reacted with various aldehydes, affording the corresponding hydrazones. These compounds allowed stereoselective preparation of a-branched amines, through 1,2-addition of both aromatic and aliphatic nucleophiles to the C=N double bond of the hydrazones. Reductive cleavage released the desired amine from the resin. Moderate to good enantiomeric excesses (50-86%) were achieved. 

The Buchwald-Hartwig amination reaction can facilitate the synthesis of nitrogen-containing heterocycles. For instance, Buchwald demonstrated that the amination reaction could be used to prepare N-arylhydrazones from hydrazones and aryl halides. Acid-catalyzed condensation of the hydrazone with a ketone then yielded the desired indoles.Hartwig described a similar arylhydrazone formation with DPPF as a ligand and CS2CO3 as a base."... 

Shimogawa, H., Kuribayashi, S., Temya, T, Suenaga, K., and Kigoshi, H. (2006) Cinachyramine, fhe novel alkaloid possessing a hydrazone and two aminals from CinachyreUa sp. Tetrahedron Lett., 47,1409-1411. 

Hydroperoxides have been obtained from the autoxidation of alkanes, aralkanes, alkenes, ketones, enols, hydrazones, aromatic amines, amides, ethers, acetals, alcohols, and organomineral compounds, eg, Grignard reagents (10,45). In autoxidations involving hydrazones, double-bond migration occurs with the formation of hydroperoxy—azo compounds via free-radical chain processes (10,59) (eq. 20). 

Mattox and Kendall have suggested that loss of bromide from the initially formed hydrazone of the a-halo ketone is facilitated by participation of the electron pair on the amine nitrogen atom. The same group has shown that semicarbazones are often superior to 2,4-dinitro-phenylhydra-zones since they can be obtained in higher yields and undergo cleavage more... 

Clerici and Porta reported that phenyl, acetyl and methyl radicals add to the Ca atom of the iminium ion, PhN+Me=CHMe, formed in situ by the titanium-catalyzed condensation of /V-methylanilinc with acetaldehyde to give PhNMeCHMePh, PhNMeCHMeAc, and PhNMeCHMe2 in 80% overall yield.83 Recently, Miyabe and co-workers studied the addition of various alkyl radicals to imine derivatives. Alkyl radicals generated from alkyl iodide and triethylborane were added to imine derivatives such as oxime ethers, hydrazones, and nitrones in an aqueous medium.84 The reaction also proceeds on solid support.85 A-sulfonylimines are also effective under such reaction conditions.86 Indium is also effective as the mediator (Eq. 11.49).87 A tandem radical addition-cyclization reaction of oxime ether and hydrazone was also developed (Eq. 11.50).88 Li and co-workers reported the synthesis of a-amino acid derivatives and amines via the addition of simple alkyl halides to imines and enamides mediated by zinc in water (Eq. 11.51).89 The zinc-mediated radical reaction of the hydrazone bearing a chiral camphorsultam provided the corresponding alkylated products with good diastereoselectivities that can be converted into enantiomerically pure a-amino acids (Eq. 11.52).90... 

Derivatives of hydrazine, especially the hydrazide compounds formed from carboxylate groups, can react specifically with aldehyde or ketone functional groups in target molecules. Reaction with either group creates a hydrazone linkage (Reaction 44)—a type of Schiff base. This bond is relatively stable if it is formed with a ketone, but somewhat labile if the reaction is with an aldehyde group. However, the reaction rate of hydrazine derivatives with aldehydes typically is faster than the rate with ketones. Hydrazone formation with aldehydes, however, results in much more stable bonds than the easily reversible Schiff base interaction of an amine with an aldehyde. To further stabilize the bond between a hydrazide and an aldehyde, the hydrazone may be reacted with sodium cyanoborohydride to reduce the double bond and form a secure covalent linkage. 

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