Search

1,3‐Difunctionalized cyclobutanes are an emerging scaffold in medicinal chemistry that can confer beneficial pharmacological properties to small‐molecule drug candidates. However, the diastereocontrolled synthesis of these compounds typically requires complicated synthetic routes, indicating a need for novel methods. Here, we report a sequential C−H/C−C functionalization strategy for the stereospecific synthesis of cis‐γ‐functionalized cyclobutyl ketones from readily available cyclobutyl aryl ketones. Specifically, a bicyclo[1.1.1]pentan‐2‐ol intermediate is generated from the parent cyclobutyl ketone via an optimized Norrish‐Yang procedure. This intermediate then undergoes a ligand‐enabled, palladium‐catalyzed C−C cleavage/functionalization to produce valuable cis‐γ‐(hetero)arylated, alkenylated, and alkynylated cyclobutyl aryl ketones, the benzoyl moiety of which can subsequently be converted to a wide range of functional groups including amides and esters. [ABSTRACT FROM AUTHOR]

1,3‐Difunctionalized cyclobutanes are an emerging scaffold in medicinal chemistry that can confer beneficial pharmacological properties to small‐molecule drug candidates. However, the diastereocontrolled synthesis of these compounds typically requires complicated synthetic routes, indicating a need for novel methods. Here, we report a sequential C−H/C−C functionalization strategy for the stereospecific synthesis of cis‐γ‐functionalized cyclobutyl ketones from readily available cyclobutyl aryl ketones. Specifically, a bicyclo[1.1.1]pentan‐2‐ol intermediate is generated from the parent cyclobutyl ketone via an optimized Norrish‐Yang procedure. This intermediate then undergoes a ligand‐enabled, palladium‐catalyzed C−C cleavage/functionalization to produce valuable cis‐γ‐(hetero)arylated, alkenylated, and alkynylated cyclobutyl aryl ketones, the benzoyl moiety of which can subsequently be converted to a wide range of functional groups including amides and esters. [ABSTRACT FROM AUTHOR]

In 2001, our curiosity to understand the stereochemistry of C−H metalation with Pd prompted our first studies in Pd(II)‐catalyzed asymmetric C−H activation (RSC Research appointment: 020 7451 2545, Grant: RG 36873, Dec. 2002). We identified four central challenges: 1. poor reactivity of simple Pd salts with native substrates; 2. few strategies to control site selectivity for remote C−H bonds; 3. the lack of chiral catalysts to achieve enantioselectivity via asymmetric C−H metalation, and 4. low practicality due to limited coupling partner scope and the use of specialized oxidants. These challenges necessitated new strategies in catalyst and reaction development. For reactivity, we developed approaches to enhance substrate–catalyst affinity together with novel bifunctional ligands which participate in and accelerate the C−H cleavage step. For site‐selectivity, we introduced the concept of systematically modulating the distance and geometry between a directing template, catalyst, and substrate to selectively access remote C−H bonds. For enantioselectivity, we devised predictable stereomodels for catalyst‐controlled enantioselective C−H activation based on the participation of bifunctional ligands. Finally, for practicality, we have developed varied catalytic manifolds for Pd(II) to accommodate diverse coupling partners while employing practical oxidants such as simple peroxides. These advances have culminated in numerous C−H activation reactions, setting the stage for broad industrial applications. [ABSTRACT FROM AUTHOR]

In 2001, our curiosity to understand the stereochemistry of C−H metalation with Pd prompted our first studies in Pd(II)‐catalyzed asymmetric C−H activation (RSC Research appointment: 020 7451 2545, Grant: RG 36873, Dec. 2002). We identified four central challenges: 1. poor reactivity of simple Pd salts with native substrates; 2. few strategies to control site selectivity for remote C−H bonds; 3. the lack of chiral catalysts to achieve enantioselectivity via asymmetric C−H metalation, and 4. low practicality due to limited coupling partner scope and the use of specialized oxidants. These challenges necessitated new strategies in catalyst and reaction development. For reactivity, we developed approaches to enhance substrate–catalyst affinity together with novel bifunctional ligands which participate in and accelerate the C−H cleavage step. For site‐selectivity, we introduced the concept of systematically modulating the distance and geometry between a directing template, catalyst, and substrate to selectively access remote C−H bonds. For enantioselectivity, we devised predictable stereomodels for catalyst‐controlled enantioselective C−H activation based on the participation of bifunctional ligands. Finally, for practicality, we have developed varied catalytic manifolds for Pd(II) to accommodate diverse coupling partners while employing practical oxidants such as simple peroxides. These advances have culminated in numerous C−H activation reactions, setting the stage for broad industrial applications. [ABSTRACT FROM AUTHOR]