Strategies for the Syntheses of Pactamycin and Jogyamycin

Regio- and Stereoselective Iodoamination of Ferrocene-Containing Allenylphosphonates: Synthesis of Multifunctional Tetrasubstituted Allylic Amines and Allylic Azides

A general and practical methodology for the regio- and stereoselective synthesis of multifunctional tetrasubstituted allylic amines and azides based on iodoamination of ferrocene-containing allenylphosphonates with anilines and sodium azide is described. A tetrasubstituted olefin moiety, as well as an iodine atom, a phosphonate, and a ferrocene group, are installed to the allylic amine motif simultaneously in moderate to good yields.

Rapid Access to Densely Functionalized Cyclopentenyl Sulfoximines through a Sc-Catalyzed Aza-Piancatelli Reaction

Sulfoximines make up a class of compounds of growing interest for crop science and medicinal chemistry, but methods for directly incorporating them into complex molecular scaffolds are lacking. Here we report a scandium-catalyzed variant of the aza-Piancatelli cyclization that can directly incorporate sulfoximines as nucleophiles rather than the classical aniline substrates. Starting from 2-furylcarbinols and sulfoximines, the reaction provides direct access to 4-sulfoximinocyclopentenones, a new scaffold bearing cyclopentenone and sulfoximine motifs, both of interest for bioactive compounds.

Progress toward the Total Synthesis of Jogyamycin Using a Tandem Ichikawa/Winstein Rearrangement

Jogyamycin is a densely functionalized aminocyclopentitol that displays potent antiprotozoal activity. Herein, we report a route toward this natural product that utilizes an unprecedented transformation involving a tandem Ichikawa-Winstein rearrangement to install the C-1/C-2 diamine core. Attempts to further functionalize the C-3/C-4 alkene en route to jogyamycin are also discussed.

Stereo-Controlled Synthesis of Vicinal Tertiary Carbinols: Application in the Synthesis of a Diol Substructure of Zaragozic Acid, Pactamycin and Ryanodol

A novel and flexible approach for the stereo-controlled synthesis of vicinal tertiary carbinols is reported. The developed strategy featured a highly diastereoselective singlet-oxygen (O2 1 ) [4+2] cycloaddition of rationally designed cyclohexadienones (derived from oxidative dearomatization of the corresponding carboxylic-acid appended phenol precursors), followed by programmed "O-O" and "C-C" bond cleavage. In doing so, a highly functionalized and versatile intermediate was identified and prepared in synthetically useful quantity as a plausible precursor to access a variety of designed and naturally occurring vicinal tertiary carbinol containing compounds. Most notably, the developed strategy was successfully applied in the stereo-controlled synthesis of advanced core structures of zaragozic acid, pactamycin and ryanodol.

Asymmetric Ketoalkylation/Rearrangement of Alkyenlfurans via Synergistic Photoredox/Brønsted Acid Catalysis

An enantioselective three-component rearrangement of alkenylfurans with various cycloalkyl silyl peroxides and anilines has been developed by merging photoredox catalysis with chiral Brønsted acid catalysis. This protocol provides expedient access to a broad spectrum of ketoalkyl-functionalized 4-aminocyclopentenones in high yields with excellent enantio- and diastereoselectivities. Diverse functional groups can be introduced via facile product derivations.

The chemistry and biology of natural ribomimetics and related compounds

Natural ribomimetics represent an important group of specialized metabolites with significant biological activities. Many of the activities, e.g., inhibition of seryl-tRNA synthetases, glycosidases, or ribosomes, are manifestations of their structural resemblance to ribose or related sugars, which play roles in the structural, physiological, and/or reproductive functions of living organisms. Recent studies on the biosynthesis and biological activities of some natural ribomimetics have expanded our understanding on how they are made in nature and why they have great potential as pharmaceutically relevant products. This review article highlights the discovery, biological activities, biosynthesis, and development of this intriguing class of natural products.

Palladium-Catalyzed Regioselective Arylation of Unprotected Allylamines

Palladium-catalyzed organometallic transformations of free amines are often unsuccessful due to side reactions, such as oxidation, that can occur. However, the ability to furnish the free amine products from these reactions is important for improving the utility and sustainability of these processes, especially for accessing their potential as medicinal and agrochemical agents. Notably, the 3,3-diarylallylamine motif is prevalent in a variety of biologically relevant structures, yet there are few catalytic approaches to their synthesis, and none involving the free amine. Herein, we describe a simple protocol for the arylation of cinnamylamines and the diarylation of terminal allylamines to generate a diverse group of 3,3-diarylallylamine products using a PdII precatalyst. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically relevant molecules are included to demonstrate the utility of the transformation.