2-Alkenyl-3- amines

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)... 

Pr)4, " borohydride-exchange resin,and formic acid. When the last is used, the process is called the Wallach reaction. Conjugated aldehydes are converted to alkenyl-amines with the amine/silica gel followed by reduction with zinc borohydride.In the particular case where primary or secondary amines are reductively methylated with formaldehyde and formic acid, the method is called the Esch-weiler-Clarke procedure. It is possible to use ammonium (or amine) salts of formic acid, " or formamides, as a substitute for the Wallach conditions. This method is called the Leuckart reaction,and in this case the products obtained are often the N-formyl derivatives of the amines instead of the free amines. Primary and secondary amines can be iV-ethylated (e.g., ArNHR ArNREt) by treatment with NaBH4 in acetic acid. Aldehydes react with aniline in the presence of Mont-morillonite KIO clay and microwaves to give the amine. Formaldehyde with formic acid converts secondary amines to the N-methyl derivative with microwave irradiation. 

Heating of a mixture of polyfluoro amines 636 and 637 resulted in a mixture in which azetine 638 was present in 15% yield (Equation 242), whereas heating of fluorinated alkenyl amines 639 furnished IV-alkyl azetines 640 selectively in excellent yields (Equation 243) <1996JFC(79)97>. 

V-I Ietero-Substituted Amines and Their /J-Functionalized Derivatives Cyclization of /V-Hetero-Substituted Alkenyl Amines... 

The aziridination of alkenes by in situ oxidation of primary amines has only been achieved intramolecularly42-47. Using A-chlorosuccinimide, the reaction proceeds via intermediate /V-chloro amines42. A good yield of the aziridine can only be obtained when the molecule is sufficiently rigid to force the amino group close to the alkene double bond. Better results are generally obtained by oxidation of the alkenyl amines with lead tetraacetate. 

Secondary alkenyl amines react normally with electrophilic selenium reagents and afford the expected cyclization products. The phenylselenyl sulfate promoted conversion indicated in Scheme 22 shows that alkenyl pyrrolidines... 

Scheme 21. Cyclization Reactions of Primary N-Protected Alkenyl Amines...

Reduction of A -(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 A -chlorosuccinimide and then... 

Addition of an aldehyde to an alkenyl-amine can provide the required alkenyl-azomethine ylide (such as 225) for intramolecular cycloaddition. An alternative is the addition of an amine to an alkenyl-aldehyde. Thus, addition of A(-methyl glycine ethyl ester to the aldehyde 227 gave the intermediate azomethine ylide 228 and hence the cycloadduct 229 (S.MS). ... 

Scheme 18 C2-arylation/alkenylation/amination of l-(pyrimidin-2-yl)-l/-/-indole via Rh, Ru, and Co catalysis.

Barluenga et al. [87] developed a one-pot synthesis for indoles from o-bromoanilines and alkenyl bromides via a cascade alkenyl amination/Mizoroki-Heck reaction. In order to improve the yields of their procedure, they studied the cyclization of preformed imine 113 to indole 114 in the presence of DavePhos and X-Phos as supporting ligands (Scheme 6.30). 

This type of cyclization reaction was applied in the synthesis of p-carbo-linones and total synthesis of dipyrrolobenzoquinone ( )-terreusinone as well. In 2005, Barluenga and co-workers reported a novel approach for the synthesis of indoles from o-bromoanilines and alkenyl halides via a palladium-catalyzed cascade process (Scheme 2.112). The reaction involves an alkenyl amination followed by an intramolecular Heck reaction. As the authors demonstrated, this process represents the first example of the participation of alkenyl amination reactions in Pd-catalyzed cascade reactions. Initially, the relative reactivity of aiyl and alkenyl bromides and chlorides towards Pd-catalyzed amination was investigated. Competition... 

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