Total Syntheses of Bryostatins 1, 7, 9 and 9-N.

Bryostatins are a family of marine natural products that have garnered significant interests, as evidenced by over 40 clinical trials. However, their extremely low natural abundance has severely limited further research. Despite significant efforts, which have led to the total synthesis of seven bryostatin members by eight independent research groups, these complex molecules present persistent challenges for stereocontrolled, large-scale, and especially divergent synthesis.

PtCl-Catalyzed Intramolecular Cyclization of α-Benzyl Allenoates to Afford Indenes and Furanones.

Indene and furanone are important ring structures widely present in active pharmaceutical molecules. Here, we have developed a straightforward method for the synthesis of indene and furanone via PtCl-catalyzed intramolecular cyclization of α-benzyl allenoates. By altering the ester substitution pattern in the α-benzyl allenoates, we can regulate the reaction site, enabling two distinct intramolecular cyclization reactions that yield both indene and furanone products, respectively.

Ligand-Controlled Regiodivergent Ring Expansion of Benzosilacyclobutenes with Alkynes Route to Axially Chiral Silacyclohexenyl Arenes.

A ligand-controlled regiodivergent and enantioselective ring expansion of benzosilacyclobutenes with internal naphthyl alkynes has been achieved by adjusting the ligand cavity size. The ligand ()-8-binaphthyl phosphoramidite, featuring small methyl groups on its arms, provides a spacious cavity that favors sterically demanding Si-Csp ring expansion, predominantly yielding axially chiral ()-1-silacyclohexenyl arenes. In contrast, the ligand ()-spiro phosphoramidite, with bulky -Bu groups on its arms, offers a compact cavity that facilitates less sterically demanding Si-Csp ring expansion, leading primarily to axially chiral ()-2-silacyclohexenyl arenes.

Lewis Base-Catalyzed Dynamic Kinetic Asymmetric Transformation of Racemic Chlorosilanes Route to -Stereogenic Silylethers.

Enantiopure -stereogenic organosilanes are highly valued in the fields of organic synthesis, development of advanced materials, and drug discovery. However, they are not naturally occurring, and their synthesis has been largely confined to resolution of racemic silanes or desymmetrization of symmetric silanes. In contrast, the dynamic kinetic asymmetric transformation (DYKAT) of racemic organosilanes offers a mechanistically distinct approach and would broaden the accessibility of -stereogenic silanes in an enantioconvergent manner.

Endoplasmic reticulum-targeted fluorescent probe with aggregation-induced emission features for imaging peroxynitrite in drug-induced liver injury model.

Drug-induced liver injury (DILI) poses a severe threat to public health. Endoplasmic reticulum (ER) stress contributes significantly to DILI pathogenesis, with peroxynitrite (ONOO) identified as a pivotal indicator. However, the temporal and spatial fluctuations of ONOO associated with ER stress in the pathogenesis of DILI remain unclear.

Controllable Si-C Bond Formation from Trihydrosilanes En Route to Synthesis of 1,4-Azasilinanes with Diverse Silyl Functionalities.

A B(CF)-catalyzed controllable inter/intra-/intermolecular Si-C bond formation process has been developed from trihydrosilane and dienamide with alkenes, anilines, or aryl iodides. A variety of 1,4-azasilinanes have been generated with diverse -cyclic heteroleptic disubstitutions on silicon, thereby expanding the range of silaazacyclic rings available for the discovery of silicon-containing drugs.

Recent Progress in the Synthesis of Silaspiranes.

Silaspiranes bearing a spiro-silicon center are promising ring frameworks for the synthesis of novel spirocyclic molecules possessing unique properties. Development of efficient methods towards these ring structures has therefore attracted considerable attentions of synthetic chemists. This minireview highlights the representative advances in the field, and is categorized into four parts according to the ring formation strategies: cyclization, annulation, ring expansion and cycloaddition.

Enantioconvergent construction of stereogenic silicon via Lewis base-catalyzed dynamic kinetic silyletherification of racemic chlorosilanes.

Organosilanes possessing an enantioenriched stereogenic silicon center are important in many branches of chemistry, yet they remain challenging to synthesize in a practical and scalable way. Here we report a dynamic kinetic silyletherification process of racemic chlorosilanes with (S)-lactates using 4-aminopyridine as a Lewis base catalyst. This enantioconvergent approach asymmetrically constructs the stereogenic silicon center in a different manner from traditional resolution or desymmetrization.

Enantioselective Synthesis of 6/5-Spirosilafluorenes by Asymmetric Ring Expansion of 4/5-Spirosilafluorenes with Alkynes.

A rhodium-catalyzed asymmetric ring expansion of 4/5-spirosilafluorenes with terminal alkynes has been developed using sterically demanding binaphthyl phosphoramidite ligand. The reaction is not only strategically distinct from cyclization or cycloaddition but also showcases the first enantioselective synthesis of axially chiral 6/5-spirosilafluorenes.

Towards Axially Chiral Pyrazole-Based Phosphorus Scaffolds by Dipeptide-Phosphonium Salt Catalysis.

Given the comparatively lower rotational barriers, the catalytic asymmetric construction of axially chiral biaryl structures, especially those containing a five-membered heterocycle, still remains a challenge. Herein, we described a general and modular protocol to access atropisomeric arylpyrazole scaffolds containing a phosphorus unit by a dipeptide phosphonium salt catalyzed reaction involving an oxidative central-to-axial chirality conversion. This reaction features excellent yields and enantioselectivities, broad substrate scope, and a low catalyst loading, delivering axially chiral phosphine compounds.

3-Silyl-3-Borylhex-4-Enoate: A Chiral Reagent for Asymmetric Crotylboration of Aldehydes.

A nonracemic 3-silyl-3-borylhex-4-enoate reagent has been developed. Its asymmetric crotylboration of aldehydes provides --homoallylic alcohols possessing a trisubstituted vinylsilane in high yields with excellent stereo- and enantioselectivity. Diverse decoration of vinylsilane and ester groups, as well as formation of functionalized THF rings, showcase the potential of the approach in the synthesis of polyketide natural products.

Enantioselective Synthesis of Spirosilabicyclohexenes by Asymmetric Dual Ring Expansion of Spirosilabicyclobutane with Alkynes.

Silaspiranes have attracted particular attention due to their chiral spiro-silicon center, which serves as an ideal carbon isostere and can endow spiro-analogs with distinct properties. Distinct from previously reported cyclization or cycloaddition strategies to form 5/5-silaspiranes, we report herein the asymmetric dual ring expansion of spirosilabicyclobutanes with alkynes to synthesize axially chiral spirosilabicyclohexenes bearing a novel 6/6-silaspirane framework. DFT (density functional theory) calculations provide the deep insight into the origin of the high enantioselectivity controlled by the sterically demanding binaphthyl phosphoramidite ligand.

(4 + 2) Annulation of ClNHCHSiMeCHCl and Propynones for the Synthesis of 1,3-Azasilinones.

A useful 1,3-, reagent (ClNHCHSiMeCHCl) and its (4 + 2) annulation with propynones have been developed. The (4 + 2) annulation is promoted by NaHCO an intermolecular -1,4-addition/intramolecular alkylation process, leading to 1,3-azasilinones in good yields. Diverse functionalization of the alkene, carbonyl, and nitrogen moieties on the 1,3-azasilinone has been demonstrated, showcasing the potential of the approach in the synthesis of bioactive molecules containing silaazacycles.

Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters.

(PhC)[BPh()]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.

Design, synthesis and biological evaluation of novel procaine derivatives for intravenous anesthesia.

A series of novel procaine derivatives for intravenous anesthesia were prepared and evaluated by physicochemical properties and pharmacodynamic experiments in vivo and in vitro. Systematic optimization of procaine led to the identification of 6f, 6g, 6h, 6o, 6p and 6q with higher TI value and moderate log D. Compared with procaine (TI = 1.

Synthesis of Silacyclohexanones from Divinylsilanes and Allylamines by a Rh-Catalyzed Cyclization.

An efficient synthesis of silacyclohexanones bearing a variety of silyl substituents has been developed by a [Rh(coe)Cl]/PCy-catalyzed cyclization of divinylsilanes with Jun's allylamine. The silacyclohexanones can be oxidized with DDQ to give the corresponding silacyclohexadienones, which are further transformed into silicon analog of 2-deoxystreptamine or alkylidenesilacyclohexadienes.

O -Assisted Four-Component Reaction of Vinyl Magnesium Bromide with Chiral N-tert-Butanesulfinyl Imines To Form syn-1,3-Amino Alcohols.

An O -assisted, four-component reaction has been developed to synthesize a wide range of syn-1,3-amino alcohols in one step. The reaction proceeds by oxygenation of vinyl magnesium bromide (component-I) with O (component-II) to give a magnesium enolate of acetaldehyde, which undergoes addition to a chiral N-tert-butanesulfinyl imine (component-III) followed by a sequential addition with excess vinyl magnesium bromide (component-IV). The approach allows diastereoselective synthesis of anti/syn- and syn/syn-3-amino-1,5-diols in good yields with high diastereoselectivity.

3-Silaazetidine: An Unexplored yet Versatile Organosilane Species for Ring Expansion toward Silaazacycles.

Small-ring silacycles are important organosilane species in main-group chemistry and have found numerous applications in organic synthesis. 3-Silaazetidine, a unique small silacycle bearing silicon and nitrogen atoms, has not been adequately explored due to the lack of a general synthetic scheme and its sensitivity to air. Here, we describe that 3-silaazetidine can be easily prepared from diverse air-stable precursors (RSONHCHSiRCHCl).

The development of an Amber-compatible organosilane force field for drug-like small molecules.

As members of the group IVA elements, silicon and carbon have long been thought of as isosteres of each other in drug design. However, the lack of silicon parameters in current main stream force fields hinders the computational study of this important element in drug discovery. Thus, in this study, we attempted to supplement the parameters of organosilanes in the General Amber Force Field (GAFF2).

Intramolecular Sakurai Allylation of Geminal Bis(silyl) Enamide with Indolenine. A Diastereoselective Cyclization To Form Functionalized Hexahydropyrido[3,4-]Indole.

A fluoride-promoted intramolecular Sakurai allylation of geminal bis(silyl) enamide with indolenine has been developed. The reaction facilitates an efficient cyclization to give hexahydropyrido[3,4-]indoles in good yields with high diastereoselectivity. The resulted , -stereochemistry further enables the ring-closing metathesis (RCM) reaction of two alkene moieties, giving a tetracyclic -hetereocycle widely found as the core structure in akuammiline alkaloids.

ArNMeCH(SiMe): a useful precursor of formal α-aminoalkyl diradicals in visible-light-mediated homo- and hetero-diaddition with alkenes.

ArNMeCH(SiMe) has been developed as a useful precursor of a formal α-aminoalkyl diradical in Ru(bpy)Cl-catalzyed addition with alkenes under visible-light-mediated photoredox conditions. This approach leads to homo-diaddition with two identical alkenes in one-pot, or hetero-diaddition with two different alkenes via a sequential operation.

One-Pot Twofold Unsymmetrical C-Si Bond 2,6-Bifunctionalization of Arenes via Sequential [1,4]-Csp to -Silyl Migration.

Twofold unsymmetrical C-Si bond bifunctionalization of 2,6-di(trimethylsilyl) benzyl alcohols has been achieved in one pot via sequential [1,4]-Csp to -silyl migration. The hydroxyl group functions as an "on-off-on" switch to control two successive silyl migrations, and 4,7-dimethyl--phenanthroline ligand favors cleavage of the endocyclic C-Si bond. Diverse Csp/Csp or Csp/Csp electrophiles can be installed at the 2- and 6-positions.

Asymmetric retro-[1,4]-Brook rearrangement of 3-silyl allyloxysilanes chirality transfer from silicon to carbon.

An asymmetric retro-[1,4]-Brook rearrangement of 3-silyl allyloxysilanes has been developed Si-to-C chirality transfer. Mechanistic studies reveal that the silyl group migrates with retention of configuration. The stereochemical outcome of the newly formed stereogenic carbon center, which has remained a longstanding question, is also clarified, suggesting a diastereoselective Si to C chirality transfer without loss of enantiomeric excess.