2-methoxy-, piperidinium

It has been found that water as a solvent accelerates the indium-mediated Barbier-type allylation and benzylation of / ,7-unsaturated piperidinium cation generated from / ,7-unsaturated a-methoxy-A-methoxycarbonylpiperidine, whereas a ring-opened allylated product has been obtained in a case using /3,7-saturated a-methoxy-A-meth-oxycarbonylpiperidine. Other solvents than water result in low yield of the allylated and benzylated products, suggesting that water is essential to generate the piperidinium intermediate from /3,7-unsaturated a-methoxy-A-methoxycarbonylpiperidine (Scheme 85).319... 

Piperidinium 2-methoxy(tellurolobenzoate) condensed with 2,4-dinitrobenzenesulfenyl chloride in dichloromethane at — 30°. The product was 2-methoxybenzoyl2,4-dinitrobenzenesulfenyl tellurium isolated in 32% yield as a yellow, crystalline solid that melted at 108-110° with decomposition3. 

Methyl 2-methoxy (tellurobenzoate) was also obtained from piperidinium 2-methoxy(tellurobenzoate) and methyl iodide in dichloromethane at — 30°. 

Analog erhiilt man Piperidinium-5- (4-methoxy-benzylidenamino)-2- (4-methoxy-phenyl) -1,3-thiazol-4-thio-lat (90% Schmp. 140-145")720. 

Bei der Hydrolyse von Piperidinium--5-nitro-lH-indazolium-3-olat zeigt sich, daB das quaternare N-Atom eine gute Abgangsgruppe ist und es zur Bildung von 5-Nitro-2-methoxy-benzoesdure-piperidinoamid363 kommt. 

Scheme 4.20 Generation o the piperidinium ion intermediate from p,y-unsaturated or-methoxy-A/-methoxycarbonylpiperidine.

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