Organotin Reagents Research Articles

Gold(I) complexes of the type [AuL{κC-2-C6H4P(S)Ph2}] [L = PTA, PPh3, PPh2(C6H4-3-SO3Na) and PPh2(2-py)]: Synthesis, characterisation, crystal structures, and In Vitro and In Vivo anticancer properties

Four new mononuclear gold (I) compounds of the type [AuL{κC-2-C6H4P(S)Ph2}] {L = PTA (1), PPh3 (2), PPh2(C6H4-3-SO3Na) (3), and PPh2(2-py) (4)} were prepared by scission of the dinuclear compound [Au2{μ-2-C6H4P(S)Ph2}2] by L or via a transmetalation reaction using the organotin reagent 2-Me3SnC6H4P(S)Ph2 and a suitable gold halide precursor. The cytotoxic potential of complexes 1–4 was evaluated against four human cancer cell lines of diverse cellular origin: cervical (HeLa), prostate (PC-3), non-small cell lung adenocarcinoma (A549), and fibrosarcoma (HT-1080). The in vitro cytotoxicity results showed that 1 demonstrated exceptional anticancer activity with IC50 values ranging from 0.08 to 3.5 μM. Complex 3, which contains a sulfonated triphenyl phosphine ligand, displayed the weakest anticancer activity with IC50 values ranging from 3.1 to >50 μM. When compared to the standard chemotherapeutic drug cisplatin, 1 displayed approximately 27-fold greater cytotoxic activity against cervical cancer cells and 3.5- and 7.5-fold greater activities against prostate and fibrosarcoma cancer cells, respectively. Additionally, 1 exhibited 3-fold selectivity for cervical cancer cells compared to non-cancerous HEK-293 cells. Mechanistic investigations revealed that 1 induced apoptosis, which was associated with elevated reactive oxygen species (ROS) and inhibition of the intracellular enzyme thioredoxin reductase. Furthermore, 1 exhibited notable antiangiogenic characteristics in an in vivo model using transgenic zebrafish Tg(fli1a:EGFP). In vivo studies using mouse xenograft models showed that complex 1 displayed superior inhibition of tumour growth (82 %) compared to the clinical drug cisplatin (29 %). Overall, these results highlight the potential of gold (I) compounds as novel antitumour agents.

Synthesis of Deoxy Pyranosides Via Fe(III) Catalyzed Regioselective Thiocarbonylation of Partially Protected Carbohydrates

AbstractRapid and efficient synthesis of targeted deoxygenated glycosides is highly desired. Herein, we disclose a two‐step procedure for the synthesis of deoxysugars from partially protected pyranosides via site‐selective thiocarbonylation followed by tin‐free Barton–McCombie deoxygenation. The selectivity can be smoothly achieved through anhydrous FeCl3 as the catalyst assisted by low‐priced benzoyltrifluoroacetonate (Hbtfa) ligand in the presence of K2CO3 as base. Further deoxygenation can be carried out using greener silicon reagent, avoiding highly toxic organotin reagents in traditional procedures. Conspicuous features of this method include mild conditions, easy operation, high selectivity and non or low toxic reagents, making it a more attractive strategy.

Trans‐Cyclooctenes as Chiral Ligands in Rhodium‐Catalyzed Asymmetric 1,4‐Additions

trans‐Cyclooctenes serve as asymmetric ligands for the rhodium‐catalyzed 1,4‐additions of organotin reagents to enones. We demonstrate, for the first time, that these chiral olefins can provide efficient coordination spheres for asymmetric metal catalysis. As the asymmetric environment around the reaction site is constructed by the trans‐cyclooctene framework, the introduction of a substituent at the allylic position further improves enantioselectivity to 93 % ee. These findings provide new chiral framework designs for the asymmetric ligands of metal catalysts.

Rapid Cu-Catalyzed [211At]Astatination and [125I]Iodination of Boronic Esters at Room Temperature.

Access to 211At- and 125I-radiolabeled compounds in excellent RCCs and RCYs was achieved in just 10 min at room temperature using a Cu catalyst. The reaction conditions are applicable to a broad class of aryl and heteroaryl boronic reagents with varying steric and electronic properties as well as late-stage astatination and iodination of anticancer PARP inhibitors. This protocol eliminates the traditional need for toxic organotin reagents, elevated temperatures, and extended reaction times, providing a more practical and environmentally friendly approach to developing α-emitting radiotherapeutics.

Homologation of halostannanes with carbenoids: a convenient and straightforward one-step access to α-functionalized organotin reagents.

A direct, single synthetic homologative transformation of halostannanes into mono- or di-substituted methyl analogues is documented. Critical for the success of the operation is the excellent nucleophilicity of carbenoid-like methyllithium reagents (LiCHXY, X, Y = halogen, OR, and CN): by simply individuating the reagents' substitution pattern, the desired functionalized fragment is delivered to the electrophile. The wide scope of the protocol is evidenced also in the case of analogous halogermanium compounds. The tandem homologation-quenching with nucleophiles and the use of α-chloroallyllithium is also discussed.

Stereo-defined synthesis of differentially all-carbon tetrasubstituted alkenes derived from (E)-1-bromo-2-iodoalkenes

An intuitive approach to differentially all-carbon tetrasubstituted olefins from a scaffold of (E)-1-bromo-2-iodoalkenes is described. The iodine atom of the scaffold selectively undertook CuTC-mediated cross-coupling reactions with organotin reagents, suppressing a side-reaction of β-halogen elimination. The resultant vinyl bromides were successfully subjected to various transformations into tetrasubstituted olefins bearing four different carbon-linked groups. The crystallographic analysis revealed that the configuration of the double bonds is fully retained in those two steps. Thus, the template strategy would provide a new entry for preparing stereo-defined tetrasubstituted alkenes.

Organotin-catalyzed regioselective benzylation of carbohydrate trans-diols

A convenient approach to regioselective benzylation of carbohydrate trans-diols was developed, where 0.1equiv. of Bu2SnCl2 and 0.1equiv. of TBABr were used as the catalysts and 2.0equiv. of BnCl was used as the benzylation reagent. In most cases, similar or better benzylation regioselectivities and isolated yields were obtained by using catalytic amounts of Bu2SnCl2, rather than stoichiometric amounts of organotin reagents required.

An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols.

In this study, [Fe(dibm)3 ] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.

Ionic liquid supported organotin reagents to prepare molecular imaging and therapy agents

Efficiency of ionic liquid supported organotin reagents in halodemetalation reaction has been investigated. High radiochemical yields of astatinated and iodinated compounds have been obtained using simple work-up procedure. This methodology represents a straightforward approach for the preparation of molecular imaging and therapy agents in nuclear medicine.

Synthesis of OSW-1 derivatives by site-selective acylation and their biological evaluation.

A strategy to site-selectively monoacylate an antitumor saponin OSW-1 was developed using an organotin reagent to rapidly access its derivatives that are useful as chemical probes. 4″-O-Acylated OSW-1 derivatives bearing a fluorophore, an alkyne tag, or biotin were prepared in good yields and were shown to maintain highly cytotoxic activity.

ChemInform Abstract: Regioselective Benzylation of Diols and Polyols by Catalytic Amounts of an Organotin Reagent.

AbstractThe methodology fails with substrates lacking a cis‐vicinal diol moiety due to formation of regioisomeric benzylation products.

Synthesis, X-ray diffraction, and density functional studies of tin(IV) compounds containing a pincer-type SNS ligand

Pincer-type compounds of general formula [{C5H3N(CH2S)2}SnRHal] [Hal = Cl, R = n-Bu (1), Ph (2); Hal = Br, R = n-Bu (3)] were prepared by the reaction of the dithiol ligand {C5H3N(CH2SH)2} with a suitable organotin reagent. The molecular structures of the compounds were established by single-crystal X-ray diffraction and exhibit trigonal bipyramidal geometry at the tin atom with degrees of tbp distortion ranging from 75 to 81°, being caused by a transannular N → Sn interaction. The behavior of all tin compounds in solution was investigated by NMR spectroscopy revealing that the N → Sn interaction in solution was present on the basis of the chemical shifts values. DFT calculations with Gaussian 09 using M06/DGDZVP were carried out for all compounds. The structural data of the total optimization agreed with the experimental results and the topological analysis indicated that bond critical points are present along the N → Sn direction.

Palladium‐catalyzed synthesis of 6‐allylcoumarins using organotin reagents as multicoupling organometallic nucleophiles

Derivatives of 6‐iodocoumarin undergoing a direct Stille cross‐coupling reaction with organotin compounds in the presence of a catalytic amount of Pd(PPh3)4 in dimethylformamide at 80°C is described in this study. It is the first report of the palladium‐catalyzed coupling of iodocoumarins with allyltributyltin under mild conditions to form alkylcoumarin compounds in good yields. © 2014 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons, Ltd.

Ortho-Metallated triphenylphosphine chalcogenide complexes of platinum and palladium: synthesis and catalytic activity.

Treatment of [PtI2(COD)] (COD = 1,5-cyclooctadiene) with 2-LiC6H4P(S)Ph2 gives the complex cis-[Pt{κ(2)-2-C6H4P(S)Ph2}2] () containing a pair of ortho-metallated triphenylphosphine sulfide rings. The selenium counterpart, [Pt{κ(2)-2-C6H4P(Se)Ph2}2] (), which exists as cis- and trans-isomers in solution, and the palladium analogues, cis-[Pd{κ(2)-2-C6H4P(X)Ph2}2] [X = S (), Se ()], are obtained by transmetallation of [MCl2(COD)] with the organotin reagent 2-Me3SnC6H4P(X)Ph2 in a 1 : 2 mol ratio. The reaction of [PdCl2(COD)] with 2-Me3SnC6H4P(X)Ph2 in a 1 : 1 mol ratio, and the reaction of with palladium(ii) acetate, give dinuclear, anion-bridged complexes [Pd2(μ-Cl)2{κ(2)-2-C6H4P(X)Ph2}2] [X = S (), Se ()] and [Pd2(μ-OAc)2{κ(2)-2-C6H4P(S)Ph2}2] (), respectively. Complexes and could not be made directly from triphenylphosphine sulfide by standard ortho-palladation procedures. The bridging framework in complexes and is cleaved by tertiary phosphines to give mononuclear derivatives [PdCl{κ(2)-2-C6H4P(X)Ph2}(PR3)] [X = S, R = Ph (); X = Se, R = Ph (); X = Se, R = 4-tolyl ()]. The selenium-containing compounds and decompose slowly in solution giving dinuclear complexes [PdCl(μ2-Se-κ(2)-P,Se-2-SeC6H4PPh2)PdCl(μ-2-C6H4PPh2)(PR3)] [R = Ph (), 4-tolyl ()]. The structure of complex establishes that the bridging 2-C6H4PPh2 group is generated by reduction of the phosphine selenide unit, not by ortho-metallation of the coordinated triphenylphosphine. The chloro-bridges of and are also cleaved by acetylacetonate (acac) and deprotonated Schiff bases forming mononuclear species [Pd{κ(2)-2-C6H4P(X)Ph2}L2] [L2 = acac, X = S (), Se (); L2 = 2-OC6H4CH[double bond, length as m-dash]NC6H4-4-R, X = S, R = OMe (), NO2 (); X = Se, R = OMe (), NO2 ()]. The ability of complexes , and the Schiff base-derivatives to catalyse Heck-Mizoroki and Suzuki-Miyaura C-C bond-forming reactions has also been investigated.

Regioselective Benzylation of Diols and Polyols by Catalytic Amounts of an Organotin Reagent

AbstractAn efficient one‐pot method for the selective benzylation of diols and polyols using 0.1 equiv. of organotin reagents and tetrabutylammonium bromide as catalyst has been developed. The diols and polyols containing a cis‐vicinal diol were regioselectively benzylated in 70–94% isolated yields. A catalytic reaction mechanism was also proposed.magnified image

ChemInform Abstract: Direct Carboxylative Reactions for the Transformation of Carbon Dioxide into Carboxylic Acids and Derivatives

AbstractReview: 77 refs.

Direct Carboxylative Reactions for the Transformation of Carbon Dioxide into Carboxylic Acids and Derivatives

Carbon dioxide is the ideal one-carbon source for organic synthesis because of its abundance, lack of toxicity, and potential as a renewable resource, but is limited by its high stability and low reactivity. The carboxylation of carbon nucleophiles with carbon dioxide to form new carbon–carbon bonds is therefore an attractive method for the synthesis of carboxylic acids and derivatives, which are in turn valuable organic products. Thus, the designing of mild methods to catalytically activate carbon dioxide and form carbon–carbon bonds is a challenge that is of both academic and practical importance. This review is focused on the direct carboxylative reaction for the transformation of carbon dioxide into carboxylic acids and derivatives from the carboxylation of carbon nucleophiles, reductive hydrocarboxylation of unsaturated compounds, carboxylation via oxidative cycloaddition, carboxylation of carbon–hydrogen bonds, and electrochemical carboxylation. 1 Introduction 2 Carboxylation of Carbon Nucleophiles 2.1 Carboxylation of Organotin Reagents 2.2 Carboxylation of Organoboron Reagents 2.3 Carboxylation of Organozinc Reagents 2.4 Carboxylation of Other Nucleophiles 3 Reductive Hydrocarboxylation of Unsaturated Compounds 4 Carboxylation via Oxidative Cycloaddition 5 Carboxylation of Carbon–Hydrogen Bonds 5.1 Carboxylation of Terminal Alkynes 5.2 Carboxylation of sp² Carbon–Hydrogen Bonds 5.3 Carboxylation of sp³ Carbon–Hydrogen Bonds 6 Electrochemical Carboxylation 7 Conclusion

ChemInform Abstract: Solvent Free Hydrostannation and Stille Reactions Using Ionic Liquid Supported Organotin Reagents.

AbstractThe title organotin reagent (I) is amenable to hydrostannation of alkynes under radical conditions to yield mixtures of E/Z‐olefins (III)/(IV).

ChemInform Abstract: Palladium‐Catalyzed Cross‐Coupling of 1,4‐Disubstituted 5‐Iodo‐1,2,3‐triazoles with Organotin Reagents.

AbstractThe desired 5‐vinyl‐1,2,3‐triazoles can be prepared as synthetically important subunits in an efficient manner from title compounds (III).

Solvent free hydrostannation and Stille reactions using ionic liquid supported organotin reagents

Hydrostannation reactions were performed cleanly using ionic liquid supported organotin reagents. These green reducing agents were used both under free radical and palladium-catalyzed conditions. One of the new ionic liquid supported organotin reagents so obtained was evaluated successfully in Stille cross-coupling reactions to give aryl-substituted allylic alcohols in solvent free conditions.