Egon Spengler the city, after the digging of a new subway tunnel resulted in the release of an ancient ghost, Spengler was forced to recruit his only four current students to act as the new Ghostbusters. Although willing to do his share of the legwork, Spengler overestimates his abilities and his aging becomes apparent when he is no longer able to work at the same level as in his younger days, generally working at the firehouse doing research while the team handle the actual 'Ghostbusting', though when the situation calls for it he will help. Melnitz is still carrying a torch for
Pictet–Spengler reaction is created. Several substrate- or auxiliary-controlled diastereoselective Pictet–Spengler reactions have been developed. Additionally, List "et al." have published a chiral Brønsted acid that catalyzes asymmetric Pictet–Spengler reactions. Tryptophans: diastereocontrolled reaction The reaction of enantiopure tryptophan or its short-chain alkylesters leads to 1,2,3,4-tetrahydro-"β"-carbolines in which a new chiral center at C-1 adopts either a "cis" or "trans" configuration towards the C-3 carboxyl group. The "cis" conduction is kinetically controlled, i.e. it is performed at lower temperatures. At higher temperatures the reaction becomes reversible and usually favours racemisation. 1,3-"trans" dominated products can be obtained with "N"-benzylated tryptophans, which are accessible by reductive