Egon Spengler is not so much ashamed as "strongly" considers irrelevant, mainly because he sees science as relevant. Spengler's faith in science was also tested in one episode where the Ghostbusters get abducted to the ghost world by the ghost of Al Capone. Spengler's scientific equipment fails until he is told by former capos of Capone (who aid the Ghostbusters in revenge for Capone double-crossing them) that only magic can harm ghosts in the ghost world as opposed to science harming ghosts in the human world, thus forcing Spengler to accept the wizardry methods of his ancestors to defeat Capone. He is
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