Design and synthesis of ether analogues as potent and selective M2 muscarinic receptor antagonists

Nonbasic Synthesis of Thioethers via Nickel-Catalyzed Reductive Thiolation Utilizing NBS-Like N-Thioimides as Electrophilic Sulfur Donors

The nonbasic synthesis of unsymmetrical thioethers via nickel-catalyzed reductive thiolation between aryl(hetero) iodides and N-thioimides is illustrated. N-Bromosuccinimide (NBS)-like N-thioimides were found quite reactive toward thiolation with carbon electrophiles, and a series of structurally varied thioethers were successfully prepared under mild reaction conditions. The transformation was featured with the new application of the NBS-like reagents, good functional group tolerance, and late-stage modification of biologically active scaffolds, thus providing an expeditious and efficient platform to construct polyfunctional thioethers.

Lewis acid / Base-free Strategy for the Synthesis of 2-Arylthio and Selenyl Benzothiazole / Thiazole and Imidazole

A Cu(II)-catalyzed Csp2-Se and Csp2-Sulfur bond formation was achieved with moderate to good yields without the aid of Lewis acid and base. The reaction is compatible with a wide range of heterocycles such as benzothiazole, thiazole, and imidazole. Also, this typical protocol is found to be active in thio-selenation via S-H activation. Additionally, we proposed a plausible mechanistic pathway involving Cu(III) putative intermediate.

Advances in Cu and Ni-catalyzed Chan–Lam-type coupling: synthesis of diarylchalcogenides, Ar2–X (X = S, Se, Te)

Advances in the Cu and Ni-catalyzed Chan–Lam-type coupling of aryl/heteroarylboronic acids with various chalcogen sources for diarylsulfide, diarylselenide and diaryltelluride synthesis are covered in this review.

Nanolayered cobalt-molybdenum sulphides (Co-Mo-S) catalyse borrowing hydrogen C-S bond formation reactions of thiols or H2S with alcohols

Nanolayered cobalt-molybdenum sulphide (Co-Mo-S) materials have been established as excellent catalysts for C-S bond construction. These catalysts allow for the preparation of a broad range of thioethers in good to excellent yields from structurally diverse thiols and readily available primary as well as secondary alcohols. Chemoselectivity in the presence of sensitive groups such as double bonds, nitriles, carboxylic esters and halogens has been demonstrated. It is also shown that the reaction takes place through a hydrogen-autotransfer (borrowing hydrogen) mechanism that involves Co-Mo-S-mediated dehydrogenation and hydrogenation reactions. A novel catalytic protocol based on the thioetherification of alcohols with hydrogen sulphide (H2S) to furnish symmetrical thioethers has also been developed using these earth-abundant metal-based sulphide catalysts.

Copper-Catalyzed Electrophilic Thiolation of Organozinc Halides by Using N-Thiophthalimides Leading to Polyfunctional Thioethers

(Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5-10 % Cu(OAc)₂ ⋅H₂ O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrophilic thiolation was extended to the introduction of trifluoromethylthio (SCF₃ ), thiocyanate (SCN), and selenophenyl (SePh) groups. The utility of this method was shown in a seven-step synthesis of a potent cathepsin D inhibitor in 34 % overall yield.

Synthesis ofN-sulfenyl-sulfoximines and -sulfenamides through a metal-free N–H/S–H dehydrocoupling reaction

A metal-free, iodine-catalyzed N–H/S–H dehydrocoupling reaction of sulfoximines and anilines with various thiols to construct sulfur–nitrogen bonds has been developed.

Fe–Cu catalyzed synthesis of symmetrical and unsymmetrical diaryl thioethers using 1,3-benzoxazole-2-thiol as a sulfur surrogate

An efficient Fe–Cu catalyzed approach is herein developed using 1,3-benzoxazole-2-thiol as a thiol surrogate for the synthesis of symmetrical and unsymmetrical diaryl thioethers.

Copper-catalyzed N-thioetherification of sulfoximines using disulfides

A novel copper-catalyzed N-thioetherification of sulfoximines under mild reaction conditions was developed using readily available disulfides as the sulfur source.

One-pot odorless thia-Michael reaction by copper ferrite nanoparticle-catalyzed reaction of elemental sulfur, aryl halides and electron-deficient alkenes

One-pot CuFe₂O₄ catalyzed reaction of aryl halides or boronic acids with sulfur and electron-deficient alkenes for generation of sulfides.

Site-Selective Suzuki-Miyaura and Sonogashira Cross Coupling Reactions of the Bis(triflate) of 2,4'-Bis(hydroxy)diphenyl Sulfone

Described is the synthesis of novel arylated and alkynylated 2,4′‐diphenyl sulfones based on what are, to the best of our knowledge, the first palladium(0)‐catalyzed cross‐coupling reactions of bis(triflates) of 2,4′‐bis(hydroxy)diphenyl sulfone. The reactions proceed with very good site‐selectivity.

Solvent-adoptable polymer Ni/NiCo alloy nanochains: highly active and versatile catalysts for various organic reactions in both aqueous and nonaqueous media

The synthesis of solvent-adoptable monometallic Ni and NiCo alloy nanochains by a one-pot solution phase reduction method in the presence of poly(4-vinylphenol) (PVPh) is demonstrated. The elemental compositions of the as-prepared alloys are determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) and energy-dispersive X-ray spectroscopy (EDS), which are matching well with the target compositions. The morphology analysis by TEM and FESEM confirms that the nanochains are made up of organized spherical monometallic Ni or bimetallic NiCo alloy nanoparticles (NPs). However, there is no nanochain formation when the alloy is prepared without the polymer PVPh. A possible mechanism for the formation of such NiCo alloy nanochains is discussed. The X-ray diffraction and selected area electron diffraction patterns reveal that the Ni/NiCo alloys are polycrystalline with fcc structure. The obtained Ni or NiCo alloy nanostructures are ferromagnetic with very high coercivity. The polymer Ni/NiCo alloy nanochains are dispersible in both water and organic media that makes them versatile enough to use as catalysts in the reactions carried out in both types of media. The catalytic activities of these Ni/NiCo alloy nanochains are extremely high in the borohydride reduction of p-nitrophenol in water. In organic solvents, these nanochains can act as efficient catalysts, under ligand-free condition, for the C-S cross-coupling reactions of various aryl iodides and aryl thiols for obtaining the corresponding cross-coupled products in good to excellent yield up to 96%. The NiCo nanochain also successfully catalyzes the C-O cross-coupling reaction in organic medium. A possible mechanism for NiCo alloy nanochain-catalyzed cross-coupling reaction is proposed.

First synthesis of 4-(arylsulfonyl)phenols by regioselective [3+3] cyclocondensations of 1,3-bis(silyloxy)-1,3-butadienes with 2-arylsulfonyl-3-ethoxy-2-en-1-ones

The formal [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with readily available 2-arylsulfonyl-3-ethoxy-2-en-1-ones resulted in regioselective formation of 4-(arylsulfonyl)phenols.

Cobalt-catalyzed aryl-sulfur bond formation

A new cobalt-catalyzed coupling of aryl halides with thiophenols and alkanethiols is reported. A variety of aryl sulfides can be prepared in excellent yields under mild reaction conditions using 1-2 mol % of CoI2(dppe) and Zn. This new cobalt-catalyzed coupling represents an interesting addition to previously known methods to synthesize thioethers. [reaction: see text].

Quantitative structure–selectivity relationship for M2 selectivity between M1 and M2 of piperidinyl piperidine derivatives as muscarinic antagonists

Muscarinic M2 receptor antagonists with high subtype selectivity (M2/M1) will decrease the toxicity in central nervous system in treatment of AD. The exploration of quantitative structure-selectivity relationship (QSSR) to muscarinic M2 receptor antagonists will provide design information for drug with fewer side effects. In this paper, CoMFA models of pK(i)(M1), pK(i)(M2) and p[K(i)(M2)/K(i)(M1)] (pK(i)(M2)-pK(i)(M1)) were used to study the subtype selectivity (M2/M1) of piperidinyl piperidine derivatives as muscarinic M2 subtype receptor antagonists. The parameters of the three models are: 0.633, 0.636 and 0.726 for cross-validated r(2) (r(cv)(2)), 0.109, 0.204 and 0.09 for the Standard error of estimate (SD), respectively. The results show the model of p[K(i)(M2)/K(i)(M1)] is the best one for design of piperidinyl piperidine derivatives as muscarinic antagonists with high subtype selectivity (M2/M1).

Muscarinic M2 antagonists: anthranilamide derivatives with exceptional selectivity and in vivo activity

Anthranilamide analogues such as 23 are potent and highly selective muscarinic M2 antagonists that also show good oral bioavailability and in vivo activity.

A general, efficient, and inexpensive catalyst system for the coupling of aryl iodides and thiols

An efficient copper-catalyzed carbon-sulfur bond formation reaction was developed. This method is particularly noteworthy given its experimental simplicity, high generality, and exceptional level of functional group toleration and the low cost of the catalyst system. [reaction: see text]

Synthesis and affinity studies of himbacine derived muscarinic receptor antagonists

A series of himbacine (1)-related analogues has been prepared featuring three different isomeric configurations with respect to the B-ring (a, b and natural c) and three different interconnecting two-carbon unsaturated units [natural (E)-ene, (Z)-ene, and yne]. The study of the binding affinities of the nine resulting compounds, including synthetic (+)-himbacine (3c), towards the M(1)-M(4) muscarine receptor subtypes revealed that analogues 3a and 5c display a promising 10-fold selectivity for the M(2) receptor as compared to the M(1) receptor.

Sulfide analogues as potent and selective M(2) muscarinic receptor antagonists

We have discovered highly potent, selective sulfide M(2) receptor antagonists with low molecular weight and different structural features compared with our phase I clinical candidate Sch 211803. Analogue 30 showed superior M(2) receptor selectivity profile over Sch 211803. More importantly, this study provided new leads for the discovery of M(2) receptor antagonists as potential drug candidates.

Metabolic stabilization of benzylidene ketal M(2) muscarinic receptor antagonists via halonaphthoic acid substitution

The potential toxicological liabilities of the M(2) muscarinic antagonist 1 were addressed by replacing the methylenedioxyphenyl moiety with a p-methoxyphenyl group, resulting in M(2) selective compounds such as 3. Several halogenated naphthamide derivatives of 3 were studied in order to improve the pharmacokinetic profile via blockage of oxidative metabolism. Compound 4 demonstrated excellent M(2) affinity and selectivity, human microsomal stability, and oral bioavailability in rodents and primates.