Suggested Reaction 2.1.2.-

Left

(13aS)-5,8,13,13a-tetrahydro-3,10-dimethoxy-6H- dibenzo[a,g]quinolizine-2,9-diol
+THF

Right

(S)-Norreticuline
+5,10-Methylene-THF

[BiSSCat | GREP ]