Aminobutanal

The maximum recommended operating pressure is 1,450 psig (10 bar, lOMpa) to avoid charring caused by breakdown products of pyridazine and 4-aminobutanal. 

The Mannich reaction is best discussed via an example. A mixture of dimethylamine, formaldehyde and acetone under mild acidic conditions gives N,N-dimethyl-4-aminobutan-2-one. This is a two-stage process, beginning with the formation of an iminium cation from the amine and the more reactive of the two carbonyl compounds, in this case the aldehyde. This iminium cation then acts as the electrophile for addition of the nucleophile acetone. Now it would be nice if we could use the enolate anion as the nucleophile, as in the other reactions we have looked at, but under the mild acidic conditions we cannot have an anion, and the nucleophile must be portrayed as the enol tautomer of acetone. The addition is then unspectacular, and, after loss of a proton from the carbonyl, we are left with the product. 

This FAD-dependent enzyme [EC 1.4.3.10] catalyzes the reaction of putrescine with dioxygen and water to produce 4-ammobutanal, ammonia, and hydrogen peroxide. 4-Aminobutanal then condenses nonenzymically to 1-pyrroline. 

A fourth possibility is the generation of H202 via oxidation of putrescine (butane-1,4-diamine 2.56). This reaction is catalyzed by copper amine oxidase (E.C. 1.4.3.6). Copper amine oxidases are homodimers in which each unit contains a copper ion and a 1,3,5-trihydroxyphenylalanine quinine co-factor. In plants copper amine oxidases generally oxidize putrescine to 4-aminobutanal (2.57). This latter compound undergoes spontaneous cyclization to A1 pyrroline (2.58), ammonia, and H202, as shown in Figure 2-12 (Medda et al., 1995). 

ACTPY was first identified in a proline-dihydroxyacetone model system by Hunter el al.22i The mechanism for its formation, shown in Scheme 5.6, is due to Hodge et al.229 De Kimpe el al.230 tried to validate this mechanism by synthesising doubly protected A-acetonyl-4-aminobutanal, but, on hydrolysis, no ACTPY was detected. 

The first committed step in TA and nicotine biosynthesis is catalyzed by putrescine JV-methyltransferase (PMT) (Fig.7.4).82 A PMT cDNA isolated from tobacco showed extensive homology to spermidine synthase from mammalian and bacterial sources.83 A-Methylputrescine is oxidatively deaminated to 4-aminobutanal, which undergoes spontaneous cyclization to form the reactive A-methyl-A1-pyrrolinium cation. Although the enzymes involved are unknown, the A-methyl-A1-pyrrolinium cation is thought to condense either with acetoacetic acid to yield hygrine as a precursor to the tropane ring, or with nicotinic acid to form nicotine. 

An intriguing stereodivergent approach to both enantiomers of slaframine, devised by Carretero and Gdmez Arrayds, commenced with the reductive amination of (/J)-glyceraldehyde acetonide 50 with the diethyl acetal of 4-aminobutanal (Scheme 7) (48). The secondary amine product 51 was transformed in three steps into a 1 1 diastereomeric mixture of a, 3-un5atuiated y-hydroxysulfones 52,... 

Selective reaction of cardol in preference to cardanol under Mannich reaction conditions with diethylenetriamine (or 4-aminobutane) and aqueous formaldehyde in methanolic solution resulted in the separation, as a lower layer, of the cardol in the form of a low polymeric Mannich base. Recovery of cardanol from the upper layer and high vacuum distillation afforded pure material containing only traces of 2-methylcardol (ref. 189). Thus technical CNSL (1 mole average mol. wt. 303g) with 40% aqueous formaldehyde (1.2 mole CHjO) and diethylenetriamine (0.125 mole) in methanol (1250ml) afforded after 30mins a dark methanol-insoluble lower... 

In contrast, reaction of diethyl propionylphosphonate with lithium bis-(trimethylsilyl)amide (LiHMDS) at -78 °C gave the expected enolate as evidenced by its highly diastereoselective condensation with benzaldehyde, leading to the formation of 3-hydroxy-2-methyl-3-phenylpropionic acid (equation 91) " . An attempt was made to develop this concept to enantioselective aldol condensation. However, condensation of a cyclic chiral propionylphosphonamidate (31), synthesized from ( S)-A-isopropyl-4-aminobutan-2-ol, with benzaldehyde yielded 3-hydroxy-2-methyl-3-phenylpropionic acid in disappointingly low 47% e.e. (equation 92)... 

Snider reported synthesis of ficuseptine (169) and juliprosine (172) containing 2,3-dihydro-l//-indolizinium alkaloids via biomimetic intramolecular Chihibabin pyridine synthesis." Two molecules of aldehyde 167 and one molecule of 4-aminobutanal dimethyl acetal 168 in acetic acid at 95 °C gave 169 in 52% yield. Meanwhile, two molecules of aldehyde 170 and one molecule of 1-pyrroline 171 in acetic acid at room temperature gave 172 in 72% yield. 

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). 

Examples of SB formation are outlined in Figure 1.28. The reaction of 4-aminobutanal and succinaldehyde yields an SB which is the intermediate of dialdehyde amine, likely a precursor of the pyrrolizidine ring system. Another example is the piperidine-2-carboxylic acid (a precursor of anabasine) obtained from a-keto- -aminocapronic acid. 

Figure 3.18 Experimental (left) and simulated (right) variable-temperature static 0 NMR spectra of the three sulfonate oxygens in 4-aminobutane-1-sulfonic acid (ABSA) at 21.1 T. Reprinted with permission from [39],...

One Nitrogen and One Otlmr Heteroatom.— iV-Nitroso-l,3-oxazepines (285) have been prepared in a one-step reaction by treating 4-aminobutan-l-ol with aldehydes in the presence of nitrous acid,i and the benzoxazepines... 

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