Egon Spengler him, which leaves him a little flustered. He celebrates his 40th birthday during this series, which would put him in his late twenties when "The Real Ghostbusters" began. Age is the largest factor causing Spengler to having transition from active ghost hunting to a mentorship role; in one episode where the original Ghostbusters guest starred on an episode the audience clearly sees middle adulthood has affected the speed and weakened the stamina of the original Ghostbusters. Although Egon Spengler does not appear in the 1990 "The Earth Day Special", his character and status as a Ghostbuster is mentioned, and Harold
Pictet–Spengler reaction hydrochloric acid forming a tetrahydroisoquinoline. Like the Mannich reaction, aldehydes give good yields while ketones tend to give lower conversion. The Pictet–Spengler reaction has been applied to solid-phase combinatorial chemistry with great success. An analogous reaction with an aryl-β-ethanol is called Oxa-Pictet–Spengler reaction The reaction mechanism occurs by initial formation of an iminium ion (2) followed by electrophilic addition at the 3-position, in accordance with the expected nucleophilicity of indoles, to give the spirocycle 3. After migration of the best migrating group, deprotonation gives the product (5). Replacing an indole with a 3,4-dimethoxyphenyl group give the reaction named the Pictet–Spengler