Harold Ramis Dan Aykroyd on the screenplay for "Ghostbusters", which became one of the biggest comedy hits of all time, in which he also starred as Dr. Egon Spengler, a role he reprised for the 1989 sequel, "Ghostbusters II" (which he also co-wrote with Aykroyd). His later film "Groundhog Day" has been called his "masterpiece". His films have been noted for attacking "the smugness of institutional life ... with an impish good [will] that is unmistakably American". They are also noted for "Ramis's signature tongue-in-cheek pep talks". Sloppiness and improv were also important aspects of his work. Ramis frequently depicted the qualities
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