Egon Spengler exhausting trek up the stairs of 55 Central Park West. While in the alternate dimension of the library, Egon is heard to groan, "Oh no," and when Ray asks if he saw something scary, Egon replies, "Stairs, lots of stairs". Before the "Return to Sedgewick Hotel" mission, Stantz comments that Spengler was once a coroner, to which he replied that he maintains interest in the subject as a hobby. Spengler appears in Beeline's "Ghostbusters" game for iOS alongside his niece, Michelle Ying. The game was released on January 24, 2013. Spengler appears in "Lego Dimensions", with archival audio of Harold
Pictet–Spengler reaction tetrahydroisoquinoline synthesis. Reaction conditions are generally harsher than the indole variant, and require refluxing conditions with strong acids like hydrochloric acid, trifluoroacetic acid or superacids. Instead of catalyzing the Pictet-Spengler cyclization with strong acid, one can acylate the iminium ion forming the intermediate "N"-acyliminium ion. The "N"-acyliminium ion is a very powerful electrophile and most aromatic ring systems will cyclize under mild conditions with good yields. Tadalafil is synthesized via the "N"-acyliminium Pictet–Spengler reaction. This reaction can also be catalyzed by AuCl and AgOTf. When the Pictet–Spengler reaction is performed with an aldehyde other than formaldehyde, a new chiral center