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Intramolecular Electrophilic Cyclization of Doubly Activated Imines Induced by Lewis Acids and Trialkylsilyl Triflates. An Efficient Route to Substituted Piperidines and Annulated Piperidine Lactones
Author(s) -
Tietze Lutz F.,
Bratz Matthias
Publication year - 1989
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19891220532
Subject(s) - chemistry , lewis acids and bases , piperidine , electrophile , intramolecular force , medicinal chemistry , intramolecular reaction , stereochemistry , derivative (finance) , organic chemistry , catalysis , financial economics , economics
Intramolecular electrophilic cyclization of imines 11a – c with two electron‐withdrawing groups at the CN bond using Lewis and Brønsted acids as well as trialkylsilyl trifluoromethanesulfonates gives the piperidines 12a – c and the annulated piperidine lactones 13a – c and 14 . 11b yields mostly 12b with the trialkylsilyl triflates and 13b with Lewis acids such as FeCl 3 on Al 2 O 3 or GaCl 3 . The reaction of 11a and 11c always results, using different methods, in the formation of the lactones 13a , 14 , and 13c , respectively. Treatment of 13b with aqueous base affords 19 , a derivative of a cyclic nonproteinogenic α‐amino acid.