Amines intramolecular bonding

C-H Amination. A number of amine-based starting materials will react with PhI(OAc)2 and a transition metal catalyst to promote selective C-H bond amination. Intramolecular oxidation of substrates such as carbamates, ureas, sulfamates, sulfonamides, and sulfamides affords the corresponding heterocycles in high yields and, in many cases, with excellent diastereocontrol (eqs 60 and 61). Insertion into optically active 3° C-H centers is reported to be stereospecific (eq 62). Chiral Ru, Mn, and Rh catalysts have all been utilized for asymmetric C-H amination, though product enantiomeric induction is variable. Many of the heterocyclic structures furnished from these reactions function as versatile precursors to 1,2- and 1,3-amine derivatives. 

Note that for 4.42, in which no intramolecular base catalysis is possible, the elimination side reaction is not observed. This result supports the mechanism suggested in Scheme 4.13. Moreover, at pH 2, where both amine groups of 4.44 are protonated, UV-vis measurements indicate that the elimination reaction is significantly retarded as compared to neutral conditions, where protonation is less extensive. Interestingy, addition of copper(II)nitrate also suppresses the elimination reaction to a significant extent. Unfortunately, elimination is still faster than the Diels-Alder reaction on the internal double bond of 4.44. 

Unlike the intermolecular reaction, the intramolecular aminopalladation proceeds more easily[13,14,166], Methylindole (164) is obtained by the intramolecular exo amination of 2-allylaniline (163). If there is another olefinic bond in the same molecule, the aminopalladation product 165 undergoes intramolecular alkene insertion to give the tricyclic compound 166[178]. 2,2-Dimethyl-l,2-dihydroquinoline (168) is obtained by endo cyclization of 2-(3,3-dimethyiallyl)aniline (167). The oxidative amination proceeds smoothly... 

When allene derivatives are treated with aryl halides in the presence of Pd(0), the aryl group is introduced to the central carbon by insertion of one of the allenic bonds to form the 7r-allylpalladium intermediate 271, which is attacked further by amine to give the allylic amine 272. A good ligand for the reaction is dppe[182]. Intramolecular reaction of the 7-aminoallene 273 affords the pyrrolidine derivative 274[183]. 

Preparative routes to aziridines and 1-azirines are derived from cycloelimination processes in which one, and sometimes two, bonds are formed directly to the nitrogen atom (Scheme 1). For aziridines these include the two intramolecular cyclization pathways involving either nucleophilic displacement by the amine nitrogen (or nitrenium anion) on the /3-carbon (route a) or nucleophilic displacement by a /3-carbanionic centre on the amine nitrogen... 

In some reactions intramolecular chalcogen nitrogen interactions may lead to stereochemical control. For example, selenenyl bromides react with C=C double bonds, providing a convenient method of introducing various functional groups. The reaction proceeds readily, but affords a racemic mixture. The modified reagent 15.22 contains a chiral amine in close interaction with the selenium atom. It reacts with olefins affording up to 97% ee of isomer A (Scheme 15.2). ... 

Apparently, cyclization involves the formation of open-chain intermediates 342, 343, further closing up to imidazolidines 344 and oxazolidines 345 which eliminate the secondary amine, thus leading to imidazolines 346 and oxazolines 347. The latter exist in the solution exclusively in the enolic forms 348, 349 which are stabilized by conjugation and intramolecular hydrogen bonds. 

Also noteworthy is the condensation of dimethyl phthalate (71) with TV.A-bis methoxycar-bonyl)alkyl- and -aryl]amines to give 3F/-3-benzazepines which exist as the intramolecularly hydrogen-bonded enol forms, e.g. 72, rather than the generally more stable benzazepinone tautomers.14... 

Likewise, amine functions on the azepine ring at an unsaturated carbon center behave as enamines and undergo hydrolysis under both acid and alkaline conditions to the benzazepinones.15,64 8084 However, hydrolysis of dimethyl l-acetyl-5-piperidino-l//-l-benz-azepine-3,4-dicarboxylate(18) yields not the benzazepinone but the tautomeric 5-hydroxy derivative 19.13 Presumably, the enol form is stabilized by intramolecular hydrogen bonding. 

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