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Iodine(III) Derivatives as Halogen Bonding Organocatalysts
Author(s) -
Heinen Flemming,
Engelage Elric,
Dreger Alexander,
Weiss Robert,
Huber Stefan M.
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201713012
Subject(s) - chemistry , solvolysis , electrophile , halogen , hypervalent molecule , lewis acids and bases , medicinal chemistry , cyclopentadiene , allylic rearrangement , ketone , denticity , organic chemistry , cationic polymerization , catalysis , iodine , alkyl , crystal structure , hydrolysis
Hypervalent iodine(III) derivatives are known as versatile reagents in organic synthesis, but there is only one previous report on their use as Lewis acidic organocatalysts. Herein, we present first strong indications for the crucial role of halogen bonding in this kind of catalyses. To this end, the solvolysis of benzhydryl chloride and the Diels–Alder reaction of cyclopentadiene with methyl vinyl ketone served as benchmark reactions for halide abstraction and the activation of neutral compounds. Iodolium compounds (cyclic diaryl iodonium species) were used as activators or catalysts, and we were able to markedly reduce or completely switch off their activity by sterically blocking one or two of their electrophilic axes. Compared with previously established bidentate cationic halogen bond donors, the monodentate organoiodine derivatives used herein are at least similarly active (in the Diels–Alder reaction) or even decidedly more active (in benzhydryl chloride solvolysis).