An official website of the United States government
Abstract A Rh(II)/Au(I) catalyzed carbene cascade approach for the stereoselective synthesis of diverse spirocarbocycles is described. The cascade reaction involves a rhodium carbene initiatedsp2C−H functionalization followed by a gold catalyzed Conia‐ene cyclization. The cascade reaction accommodates a variety of aryl substituents as well as ring sizes and proceeds with high diastereoselectivity providing access to diverse spirocarbocycles. magnified image
more »
« less
Umpolung Strategy for Arene C−H Etherification Leading to Functionalized Chromanes Enabled by I(III) N ‐Ligated Hypervalent Iodine Reagents
Abstract The direct formation of aryl C−O bonds via the intramolecular dehydrogenative coupling of a C−H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C−H etherification via an umpoled alcohol cyclization mediated by an I(III)N‐HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization‐iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O‐intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2‐shift pathways. magnified image
more »
« less
- PAR ID:
- 10445110
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Synthesis & Catalysis
- Volume:
- 363
- Issue:
- 21
- ISSN:
- 1615-4150
- Format(s):
- Medium: X Size: p. 4867-4875
- Size(s):
- p. 4867-4875
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The direct C−H acyloxylation of polycyclic aromatic hydrocarbons (PAHs) with carboxylic acids as the acyloxylating agents was achieved via the electron‐donor‐acceptor (EDA) complexes between PAHs andN‐iodosuccinimide (NIS). This visible light‐assisted metal‐free C−H acyloxylation reaction provides an easy access to the desired aryl carboxylates from readily available PAHs and aliphatic and aromatic carboxylic acids under mild reaction conditions. magnified imagemore » « less
-
Abstract A Rh(I)‐catalyzed C6‐selective C−H arylation of 2‐pyridones with inexpensive, readily available, safe and structurally diverse aryl carboxylic acids with the aid of a pyridine directing group is developed. This decarbonylative arylation protocol features an easy‐to‐handle catalytic system, and is amenable to diversely substituted 2‐pyridones and aryl carboxylic acids. It allows access to a wide range of C6‐arylated 2‐pyridones, including those that are difficult to prepare using conventional C−H arylation processes. The method tolerates various electron‐neutral, electron‐rich and electron‐deficient functional groups, and affords the products in 41–91% yields. magnified imagemore » « less
-
Abstract Isochromenes are important pharmacophores present in biologically active molecules and natural products. Their synthesis is generally limited to cyclization of phenyl propargyl ether precursors under transition metal catalyzed conditions. Herein, we present a novel disconnection that rapidly constructs isochromene derivatives through a cascade radical cyclization strategy. Generation of aryl radicals by SET reduction of 2‐iodo benzyl allenyl ethers is followed by radical cyclization to construct the isochromene core with formation of an allylic radical. The allylic radical then undergoes coupling with the azaallyl radical to give products in good to excellent yields. The elaborated 2‐iodo phenyl propargyl ether precursors can be used to construct isochromenes bearing various functional groups. magnified imagemore » « less
-
Transition Metal‐Free Aroylation of Diarylmethanes with N ‐Bn‐ N ‐Boc Arylamides and N ‐AcylpyrrolesAbstract In the last 20 years, efficient transition metal catalysts for the α‐arylation of enolates have been introduced. Despite the popularity and utility of these reactions, there remains room for improvement (reduced costs, elimination of transition metals and specialized ligands). Herein is reported a general, scalable and green method for aroylation of simple diarylmethane pronucleophiles through direct acyl C−N cleavage ofN‐Bn−N‐Boc arylamides andN‐acylpyrroles under transition metal‐free conditions. Importantly, a 1 : 1 ratio of the amide to the pronucleophile is employed. Unlike use of Weinreb amides, this method avoids preformed organometallics (organolithium and Grignard reagents) and does not employ cryogenic temperatures, which are difficult and costly to achieve on scale. The operationally simple protocol provides straightforward access to a variety of sterically and electronically diverse 1,2,2‐triarylethanones, a group of compounds with high‐value in medicinal chemistry. magnified imagemore » « less
