Amines, allylic tertiary

Olefins are also the products of hydroboratlon of enamines, followed by treatment of the organoborane products with hot acid (543,544). The reduction of enamines with sodium borohydride and acetic acid (545) and the selective reduction of dienamines with sodium borohydride to give homo-allylic tertiary amines (138-140,225,546,547), has been applied to the synthesis of conessine (548) and other aminosteroid analogs (545,549-552). Further examples of the reduction of imonium salts by sodium borohydride can be found in the reduction of Bischler-Napieralski products, and other cyclic imonium salts (102). 

Sigmatropic rearrangement of allylic tertiary amine-A -oxides to give O-allyl hydroxylamines ... 

Alfytic tertiary amines The reagent serves as a starting material for a regio- and stereospecific synthesis of allylic tertiary amines by the Wittig-Horner reaction shown in the example. 

The most conspicuous property of aliphatic amines, apart from their fishy smell, is their high basicity, which usually precludes N-alkylations under acidic reaction conditions (last reaction, Scheme 6.3). Hence, alkylation of amines with tertiary alkyl groups is not usually possible without the use of highly stabilized carbocations which can be formed under basic reaction conditions. Rare exceptions are N-alkyla-tions of amines via radicals (Scheme 4.2), copper-catalyzed propargylations (Scheme 6.3), and the addition of amines to some Michael acceptors and allyl palladium or iridium complexes. Better strategies for the preparation of tert-alkylamines include the addition of Grignard reagents to ketone-derived imines [13] or the reduction of tert-alkyl nitro compounds. 

As an equivalent of ammonia or a primary amine, either the phthalimide anion (crown ether complex or tetrabutylammonium salt) and jV-methyl-4-methylbenzenesulfonamide were used in the addition to allylic tertiary amines40. The addition was unsuccessful for 1,2-disub-stituted double bonds. When two stereogenic centers were formed the relative stereochemistry was not determined, e.g., formation of 1. 

Benzylic and allylic tertiary amines may be reduced to hydrocarbons using one of two methods. Oxidation to an amine oxide followed by reduction with lithium in liquid ammonia provides one of these... 

The intrinsic limitation for the direct CROP of IV-H-cyclic amines for preparing defined linear PHAIs is the similar nucleophilicity of the amino groups of the monomer and the polymer. As such, the cationic chain ends are reactive towards both the monomer and the polymer, leading to the formation of hyperbranched polymers. Lower degrees of branching may be achieved by a mixed feed containing both aziridine and an N-suhstituted aziridine, but this also leads to the incorporation of allylated tertiary amine groups. ... 

Scheme 1S.34 Synthesis of ammonium ylides by allylic amination with tertiary amines.

Based on early mechanistic experiments, we propose that aminoester 139 and palladium(II)-n-allyl conplex 140 establish an unfavorable equilibrium with palladium(0) and ammonium salt 141 (Scheme 1 S.3ST As soon as this unstable ammonium intermediate is formed, it undergoes a rapid deprotonation to generate ammonium ylide 142, which is transformed into the observed [2,3]-rearrangement product 143 through an exo transition state. An unfavorable equilibrium for the palladium-catalyzed ammonium salt formation, in conjunction with the facile conversion of ammonium salts into the [2,3]-rearrangement products, could explain the difficulty in observing any ammonium intermediates. This mechanistic proposal also accounts for why catalytic intermolecular allylic amination with tertiary amines has never been reported before. 

A palladium-catalysed allylic amination involving tertiary aminoesters and allylcar-bonates has been reported (Scheme 142) " ... 

New syntheses of cyclic tertiary amines from iV-chloramines, allylic tertiary amines from Pd(0) complexes, 2,6-disubstituted anilines from enamines, and 2-arylaminoalcohols via a photo-Smiles rearrangement have been published. 

Although allylic amines are available by a variety of synthetic methods, regiochemical and stereochemical control is often difficult. A successful application of the Wittig-Homer reaction to this problem now allows the synthesis of (Ey and (Z)-allylic tertiary amines from aldehydes and ketones for which, in the latter case, stereoselectivity favours the formation of the intermediate threo-isomer (Scheme 20). Syntheses of tertiary allylic amines by sodium boro-... 

Allylic tertiary amines can be displaced by the reaction of acetic anhydride and sodium acetate. The allylic acetate is the major product, as shown in eq 8. 

Stevens rearrangement. We envisioned that a palladium-catalyzed ally lie amination of a tertiary aminoester 42 with an allylic carbonate 43 in the presence of base should directly provide ammonium ylide 38 and subsequent thermal rearrangement product 39 (Scheme 13). Although primary and secondary allylic amines have extensively been used in allylic amination chemistry, tertiary amines are not considered competent substrates for this mode of reactivity. Despite the lack of literature precedent, Arash was determined to develop this reaction. 

The oxidation of higher alkenes in organic solvents proceeds under almost neutral conditions, and hence many functional groups such as ester or lac-tone[26,56-59], sulfonate[60], aldehyde[61-63], acetal[60], MOM ether[64], car-bobenzoxy[65], /-allylic alcohol[66], bromide[67,68], tertiary amine[69], and phenylselenide[70] can be tolerated. Partial hydrolysis of THP ether[71] and silyl ethers under certain conditions was reported. Alcohols are oxidized with Pd(II)[72-74] but the oxidation is slower than the oxidation of terminal alkenes and gives no problem when alcohols are used as solvents[75,76]. 

Addition of several organomercury compounds (methyl, aryl, and benzyl) to conjugated dienes in the presence of Pd(II) salts generates the ir-allylpalladium complex 422, which is subjected to further transformations. A secondary amine reacts to give the tertiary allylic amine 423 in a modest yield along with diene 424 and reduced product 425[382,383]. Even the unconjugated diene 426 is converted into the 7r-allyllic palladium complex 427 by the reaction of PhHgCI via the elimination and reverse readdition of H—Pd—Cl[383]. 

Allylation under basic conditions. Allylation can be carried out under basic conditions with allylic acetates and phosphates, and under neutral conditions with carbonates and vinyloxiranes. The allylations under neutral conditions are treated separately in Section 2.2.2.1 from those under basic conditions. However, in some cases, allylations of the same substrates are carried out under both basic and neutral conditions to give similar results. These reactions are treated together in this section for convenience. Allylic acetates are widely used for Pd-catalyzed allylation in the presence of bases tertiary amines or NaH are commonly used[6,7,4l]. As a base, basic alumina or ICF on alumina is conveniently used, because it is easy to remove by filtration after the reaction[42]. Allyl phosphates are more reactive than acetates. The allylation with 40 proceeds stepwise. At first allylic phosphate reacts with malonate and then allylic acetate reacts with amine to give 41(43]. 

Pd(dba)DPPB, 2-thiobenzoic acid, THF, 70-100% yield.Tertiary allyl-amines are cleaved efficiently at 20°, but secondary allylamines require heating to 60° to achieve cleavage. Thus, it is possible to monodeallylate a diallylamine by running the cleavage at 20°. "... 

Following the radical pathway" the next step is a homolytical cleavage of the N-R bond. The rearrangement to yield the tertiary amine 3 then proceeds via an intermediate radical-pair 4a. The order of migration is propargyl > allyl > benzyl > alkyl ... 

By Tertiary Allylic Amines Zwitterionic Aza-Cope Rearrangement. . . 190... 

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