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p K a Values of Chiral Brønsted Acid Catalysts: Phosphoric Acids/Amides, Sulfonyl/Sulfuryl Imides, and Perfluorinated TADDOLs (TEFDDOLs)
Author(s) -
Christ Philipp,
Lindsay Anita G.,
Vormittag Sonja S.,
Neudörfl JörgM.,
Berkessel Albrecht,
O'Donoghue AnnMarie C.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101157
Subject(s) - chemistry , phosphoric acid , sulfonyl , catalysis , brønsted–lowry acid–base theory , organic chemistry , organocatalysis , combinatorial chemistry , stereochemistry , enantioselective synthesis , alkyl
Measure what is measurable , and make measurable what is not so! This timeless quotation by Galileo forms the basis of all quantitative understanding, including asymmetric organocatalysis. We report p K a values for 15 chiral Brønsted acid catalysts in DMSO solutions (see scheme): the strongest acids were bis‐sulfonyl/sulfuryl imides (p K a =1.7–1.9) followed by phosphoric acids/amides (p K a =2.4–4.2). A new class of chiral Brønsted acids, tetrakis‐perfluoroalkyl analogues of TADDOLs (TEFDDOLs) have p K a s from 2.4 to 5.7.