Hydrogen bonding in organic synthesis; enhanced reactivity of aromatic compounds capable of hydrogen bonding to fluoride

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp2 carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.

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Urea-Catalyzed Functionalization of Unactivated C–H Bonds

10.26434/chemrxiv.11886789 ◽

2020 ◽

Author(s):

Alex L. Bagdasarian ◽

Stasik Popov ◽

Benjamin Wigman ◽

Wenjing Wei ◽

woojin lee ◽

...

Keyword(s):

Hydrogen Bonding ◽

Organic Synthesis ◽

High Energy ◽

Acid Catalysts ◽

Potential Utility ◽

New Paradigm ◽

Lewis Acid Catalysts ◽

Reaction Conditions ◽

Highly Active ◽

Acidic Nature

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp2 carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.

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Recent Advances in C–Br Bond Formation

Synlett ◽

10.1055/s-0037-1610772 ◽

2021 ◽

Author(s):

Ying-Yeung Yeung ◽

Jonathan Wong

Keyword(s):

Organic Synthesis ◽

Aromatic Compounds ◽

Bond Formation ◽

Cross Coupling ◽

Catalytic Site ◽

Atom Transfer ◽

Bond Forming ◽

Recent Advances ◽

Catalytic Asymmetric ◽

Site Selective

AbstractOrganobromine compounds are extremely useful in organic synthesis. In this perspective, a focused discussion on some recent advancements in C–Br bond-forming reactions is presented.1 Introduction2 Selected Recent Advances2.1 Catalytic Asymmetric Bromopolycyclization of Olefinic Substrates2.2 Catalytic Asymmetric Intermolecular Bromination2.3 Some New Catalysts and Reagents for Bromination2.4 Catalytic Site-Selective Bromination of Aromatic Compounds2.5 sp3 C–H Bromination via Atom Transfer/Cross-Coupling3 Outlook

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