Intramolekulare Aromatenalkylierungen, 31. Mitt.: Synthese und Cyclisierung von 1,4‐Dimethyl‐3‐phenethyl‐1,2,3,6‐tetrahydropyridin. Intramolecular Alkylation of Aromatic Compounds, XXXI: Synthesis and Cyclisation of 1,4‐Dimethyl‐3‐phenyl‐ethyl‐1,2,3,6‐tetrahydropyridine