Egon Spengler a bronze bust of Harold Ramis as the film's version of Spengler is seen just as Erin Gilbert leaves her office. During the credits of "Ghostbusters", the words "For Harold Ramis" are seen. Spengler's hair was changed from brown in the films (Ramis' natural hair color) to a blond pompadour in the animated series (Spengler wore his hair in a ponytail on "Extreme Ghostbusters"). This was reportedly done due to legal issues concerning character / actor likenesses. Despite his leanings toward science, Spengler has a family history of witchcraft (three ancestors, Zedekiah, Eli and Ezekiel, were wizards), of which he
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