Convergent Synthesis of Tetrasaccharide Fragment of Cervimycin K

Pd-Catalyzed Counter-Steric Site- and Chemoselective Glycosylation: Total Synthesis of Fridamycin A and Himalomycin B

Here, we report a de novo synthetic strategy toward fridamycin-type glycoside natural products. A salient feature of the method is highlighted by the Pd-catalyzed asymmetric hydroalkoxylation of fridamycin A methyl ester with alkoxyallene, which enables site- and chemoselective introduction of 2,3,6-trideoxyglycosysides to various hydroxyl positions in a highly controlled manner. A unique advantage of this method is demonstrated by the total synthesis of himalomycin B and a C4'-epi derivative of the proposed structure of amicenomycin B.

Chiral Acetal-Based Stereo-Controlled Degradable Polymer Synthesis

The precise synthesis of chiral polymers remains a significant challenge in polymer chemistry, particularly for applications in advanced biomedical and electronic materials. The development of degradable polymers is important for eco-friendly and advanced materials. Here, we introduce a stereo-controlled degradable polymer via cascade enyne metathesis polymerization and enantioselective acetal synthesis through Pd-catalyzed asymmetric hydroamination. This approach allows for the creation of chiral acetal-based polymers with controlled stereochemistry and degradability, highlighting their potential for use in drug delivery and electronic applications. This concept article reviews the background, development, and potential applications of these stereo-controlled degradable polymers.

Asymmetric Pd/Organoboron-Catalyzed Site-Selective Carbohydrate Functionalization with Alkoxyallenes Involving Noncovalent Stereocontrol

Herein, we demonstrate the robustness of a synergistic chiral Pd/organoboron system in tackling a challenging suite of site-, regio-, enantio- and diastereoselectivity issues across a considerable palette of biologically relevant carbohydrate polyols, when prochiral alkoxyallenes were employed as electrophiles. In view of the burgeoning role of noncovalent interactions (NCIs) in stereoselective carbohydrate synthesis, our mechanistic experiments and DFT modeling of the reaction path unexpectedly revealed that NCIs such as hydrogen bonding and CH-π interactions between the resting states of the Pd-π-allyl complex and the borinate saccharide are critically involved in the stereoselectivity control. Our strategy thus illuminates the untapped potential of harnessing NCIs in the context of transition metal catalysis to tackle stereoselectivity challenges in carbohydrate functionalization.

Formal Synthesis of (+)-Sinefungin by Way of Sequential Asymmetric Metal Catalysis

Here, we report a de novo approach toward (+)-sinefungin, a potent inhibitor of the physiological methyl transfer process. A key feature is represented by the sequential metal catalysis combining Pd-catalyzed hydroalkoxylation and ring-rearrangement metathesis. The unique advantage of the method is highlighted by the unprecedented complete control of the C6 stereocenter.

Total Synthesis of the Purported Structure of Branched Resin Glycosides Merremoside G and H2

The first total synthesis of the purported structure of branched resin glycosides merremoside G and H2 is accomplished. A signature step is represented by the sequential transition-metal-catalyzed coupling of stable trisaccharide homoallylic alcohol and monosaccharide alkoxyallene to afford the pentasaccharide skeleton. This de novo strategy is conducted under mild conditions with no need of preactivation. In addition, it allows for efficient preparation of the target compounds in combination with late-stage functionalization.

Synthesis of the Tetrasaccharide Glycone Part of Tetrocarcin A

A de novo synthesis of the tetrasaccharide fragment of tetrocarcin A is described. The key feature of this approach is highlighted by the regio- and diastereoselective Pd-catalyzed hydroalkoxylation of ene-alkoxyallenes with an unprotected l-digitoxose glycoside. The subsequent reaction with digitoxal in combination with chemoselective hydrogenation generated the target molecule.

Synthetic Study toward Saccharomicin Based upon Asymmetric Metal Catalysis

Here, we report a de novo metal-catalyzed approach toward the stereoselective glycosidic bond formation in saccharomicin. The signature step is highlighted by the Pd-catalyzed asymmetric coupling of ene-alkoxyallenes and highly functionalized alcohol substrates. The reaction showed high chemo-, regio-, and ligand-driven diastereoselectivity. In combination with the ring-closing metathesis and late-stage functionalization, this method led to highly efficient synthesis of saccharosamine-rhamnose and rhamnose-fucose fragments.