Acyclic amines

Depending on the relative amount of reagents, three types of products may be obtained in the reaction of hydroxymethylphosphines with amines acyclic aminomethylphosphines, 1,3,5-diazaphosphorinanes, and 1,5,3,7-diazadiphosphacyclooctanes. Indeed, the interaction of phosphorus-containing diols with 1 mol of amine gives eight-membered heterocycles. The initial assumption about the formation of 1,3-azaphosphetidines... 

The simplest isolable species that fits this description is piperazine (27) with an enthalpy of formation44 of 29.4 kJ mol-1. Can we reliably estimate this value in terms of the conceptually simpler acyclic amines, acyclic polyamines, alicyclic amines or other heterocycles One may estimate it simply as the sum of the enthalpy of formation of cyclohexane (2, n = 6) and twice the exchange energy, S5. The predicted value is 21 kJmol-1, suggestive of at least 7 kJmol-1 of strain. Do not forget that 27 should enjoy stabilization as befits its being a vie-diamine. This destabilization is twice that of piperidine (3, n = 6) as relatedly defined by its measured enthalpy of formation and that estimated by summing the enthalpy of formation of cyclohexane and 1 -85. Equivalently, disproportionation reaction 30 is found to be thermoneutral. 

L8 ArBr and Arl with 2° amines (acyclic and cyclic) also with 1° anilines, no aliphatic... 

TERTIARY AMINES Acyclic tertiary amines Pyrrolizidines Phenanthroindolizidines Phenanthroquinolizidines Harringtonine and isoharringtonine Dimeric tetrahydroisoquinolines Dimeric indole alkaloids... 

The molecular formula (C5H13N) indicates no degrees of unsaturation (see Section 15.16), so all of the isomers must be acyclic amines. The following three isomers are aU tertiary amines (acyclic and fully saturated), and none of them have a chirality center ... 

Mimk and Kim (60) have reported the preparation of the enamines of several acyclic ketones by refluxing the ketone with the amine for 66 hr to 76 days. For example the morpholine enamine of 2-pentanone was found to consist only of 121. 

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). 

The addition of secondary amines to acetylenes is most applicable to the synthesis of conjugated acyclic enamines (50,171,172). Particularly the addition to acetylenic esters and sulfones has been investigated (173-177) and it appears that an initial trans addition is followed by isomerization to more stable products where the amine and functional group are in a trans orientation (178). Enamines have also been obtained by addition of secondary amines to allenes (179). 

The mechanism of the Cook-Heilbron reaction between a-aminonitriles and dithioformic ester 6 proceeds via an acyclic intermediate 7, as proven by its isolation in several cases. Nucleophilic attack of the amine function on the sulfur-bearing carbon leads to the elimination of hydrogen sulphide. Cyclization of the acyclic thiacetoamide results in a five membered ring which aromatises favourably to give 5-amino-2-benzylthiazole 8. 

Most studies in this field have been on nitrones. One of the reasons for this is probably because nitrones are readily available compounds that can be obtained from aldehydes, amines, imines, and oximes [2, 11]. Moreover, most acyclic ni-... 

Acylation of norephedrine (56) with the acid chloride from benzoylglycolic acid leads to the amide (57), Reduction with lithium aluminum hydride serves both to reduce the amide to the amine and to remove the protecting group by reduction (58), Cyclization by means of sulfuric acid (probably via the benzylic carbonium ion) affords phenmetrazine (59), In a related process, alkylation of ephedrine itself (60) with ethylene oxide gives the diol, 61, (The secondary nature of the amine in 60 eliminates the complication of dialkylation and thus the need to go through the amide.) Cyclization as above affords phendimetra-zine (62), - Both these agents show activity related to the parent acyclic molecule that is, the agents are CNS stimulants... 

The reaction is effective with both acyclic and cyclic amides., or lactams, and is a good method for preparing cyclic amines. 

Imide-terminated telechelics are also synthesized by metathesis depolymerization, and it is found that phthalimide-substituted olefins allow for productive depolymerization when only one methylene spacer separates the nitrogen atom and the olefin (Fig. 8.21). This combination of steric hindrance around the nitrogen lone pair and decreased electron donation from resonance prevents the negative neighboring group effect. However, secondary acyclic amines are unable to produce telechelics through metathesis depolymerization because of unfavorable catalyst-amine interactions. 

Cyclic and/or acyclic aliphatic ketones > C3 Secondary or tertiary aliphatic amines with 0-12 —... 

Reduction of iV-(3-bromopropyl) imines gives a bromo-amine in situ, which cyclizes to the aziridine. Five-membered ring amines (pyrrolidines) can be prepared from alkenyl amines via treatment with N-chlorosuccinimide (NCS) and then BusSnH. " Internal addition of amine to allylic acetates, catalyzed by Pd(PPh3)4, leads to cyclic products via a Sn2 reaction. Acyclic amines can be prepared by a closely related reaction using palladium catalysts. Three-membered cyclic amines (aziridines)... 

Pappalardo, J.A. The Acyclic Aliphatic Tertiary Amines Macmillan NY, 1965, p. 14. 

The reactions of boron trifluoride adducts of ammonia,and primary, secondary, and tertiary amines with phosphorus pentachloride have been studied and in the first two cases acyclic phosphazenes were obtained. With the ammonia-adduct, a previously characterized phosphazene salt was obtained ... 

Like amine oxide elimination, selenoxide eliminations normally favor formation of the E-isomer in acyclic structures. In cyclic systems the stereochemical requirements of the cyclic TS govern the product composition. Section B of Scheme 6.21 gives some examples of selenoxide eliminations. 

Organic-Base Catalyzed. Asymmetric direct aldol reactions have received considerable attention recently (Eq. 8.98).251 Direct asymmetric catalytic aldol reactions have been successfully performed using aldehydes and unmodified ketones together with chiral cyclic secondary amines as catalysts.252 L-proline and 5,5-dimethylthiazolidinium-4-carboxylate (DMTC) were found to be the most powerful amino acid catalysts for the reaction of both acyclic and cyclic ketones as aldol donors with aromatic and aliphatic aldehydes to afford the corresponding... 

A disubstituted butyramide, disopyramide, distantly related to some acyclic narcotics interestingly shows good antiarrhythmic activity. Alkylation of the anion from phenylacetonitrile with 2-bromopyridine yields 99. Alkylation of the anion from the latter with N,N-diisopropyl-2-chloroethyl-amine leads to the amine 100. Hydration of the... 

Imines, either acyclic or macrocyclic but invariably multidentate, have a rich coordination chemistry that has been investigated at length. The 7r-accepting ability of imine donors results in the stabilization of lower oxidation states relative to their saturated amine analogs, and there exist many air-stable divalent imine complexes of Co, in contrast to amine relatives. The hexa-methyl-diene (52) has been the most intensively studied ligand of this class, particularly when complexed with Co. In addition, Co complexes of the dimethyl (53),295,296 tetramethyl (54),297 pentamethyl (55)298 and octamethyl (56)299 macrocyclic dienes are also known. In the presence of... 

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