Allyl amines, pyridines from

Reactions induced by ultrasonic irradiation of methyl 9,12-dioxostearate with hydrazines in water in the presenee of acidic alumina gave high yields of pyridazine fatty esters directly (95). The synthesis of novel piperidine- [25] and pyridine- [26] containing long-chain fatty ester derivatives has been reported starting from methyl wo-ricinoleate, 9-hydroxy-18 l(12Z) (96). Allylic amination of methyl oleate with bis(A-p-toluenesulfonyl)sulfodiimide gave a mixture of methyl ll-amino-(iV-p-toluenesulfonyl)-18 l(9 ) and methyl 8-amino-(Af-p-toluenesulfonyl)-18 l(9 ) (97). 

Allyl amines and alkynes were explored as starting materials for pyridines synthesis by Jun and coworkers as well [109]. The reaction proceeded through a sequential Cu(II)-promoted dehydrogenation of the allylamine and Rh(III)-catalyzed iV-annulation of the resulting a,/3-unsaturated imine and alkyne. Moderate to good yields of pyridines can be isolated (Scheme 3.52). This transformation was later on explored with ruthenium catalyst [110]. In the presence of [ RuCl2(p-cymene) 2] (0.1 equiv.), KPFe (0.1 equiv.), and Cu(OAc)2 (1 equiv.) in tAmOH at 100°C, the desired pyridine derivatives were formed in good yields. In this case, the reaction started with C-H activation and then insertion to alkynes which is different from the rhodium catalyzed case. 

Scheme 3.52 Rh-catalyzed synthesis of pyridines from allyl amines and alkynes.

A synthesis of pyridines from allyl amines and alkynes, which involves sequential Cu(II)-promoted dehydrogenation of the allylamine and Rh(III)-catalysed Ai-annulation of the resulting a, -unsaturated imine and alkyne, has been developed. A plausible mechanism (Scheme 4) involves an initial Cu(OAc>2-induced oxidation of allylamine to form an imine. This is followed by chelation-assisted, Rh(in)-catalysed C-H bond activation at the y-position of the imine to give the rhodacycle complex. ... 

Several ring-fused tetrazole compounds have been reported. 2-Methyl-3-cyanopyridines were converted into their corresponding 2-azidomethyl derivatives, which underwent intramolecular cycloaddition reactions to give 3-(tetrazol-5-yl)pyridines 186 <04TL9127>. Fused tetrazole derivatives 187 were obtained via tandem cycloaddition and yV-allylation reactions <04JOC1346>. Expeditive synthesis of homochiral fused tetrazole piperazines 188 from 3-amino alcohols has been reported <04TL3725>. A novel Ugi-five-center-four-component reaction (U-5C-4CR) of aldehydes, primary amines, trimethylsilyl azide and 2-isocyanoethyl tosylate afforded tetrazolopiperazine type compounds <04TL6421>. 

Product studies have demonstrated that I-phenyl and 1,1-diarylalkene radical cations react with nitrogen-centered nucleophiles such as amines and pyridines by both addition and deprotonation. The addition reactions occur by a mechanism analogous to that shown in Scheme I for methanol addition. Deprotonation by an amine or pyridine base is an alternate possibility for radical cations derived from 2-alkyl-substituted alke-nes and leads to an allylic radical (Eq. 19). Reduction of this radical by the sensitizer radical anion generates an anion that is protonaled at either the original position to regenerate starting... 

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