α-Substituierte Phosphonate. 43. Synthese und Reaktivität von 1,2,3,4-Tetrahydroisochinolin-1-phosphonaten

α-Substituted Phosphonates. 43. Synthesis and Reactivity of 1,2,3,4-Tetrahydroisochinolin-1-phosphonates N-Alkyl- and N-arylsubstituted 1,2,3,4-tetrahydroisochinolin-1-phosphonates 1 have been synthesized from the corresponding 3,4-dihydroisochinoliniumbromides 7 and triethyl-phosphite. The N-unsubstituted 1,2,3,4-tetrahydroisochinolin-1-phosphonate 10 is available starting from the 1,2,3,4-tetrahydroisochinolin-1-phosphonic acid by esterification with triethylformate and splitting off the formyl group of the primarily formed N-formyl derivative 14 . – N-Quarternated tetrahydroisochinolines 19 and the 1-phosphorylated derivatives 17 , respectively react with triethyl-phosphite in an unexpected way by dealkylation and not by splitting off the isochinolinring. – By Horner-synthesis with 1 the 1-aralkylidene-isochinolines 23 are available in moderate yields.