Design, synthesis, and X-ray structural studies of a series of highly potent, selective, and drug-like G protein-coupled receptor kinase 5 inhibitors.

G protein-coupled receptor kinase 5 (GRK5) has emerged as a potential drug development target against heart failure and cancer. A close homolog, GRK6 represents a therapeutic target for multiple myeloma. We have rationally designed a series of highly selective, potent, noncovalent, and drug-like GRK5 inhibitors.

3-Heterosubstituted Benzofurans from Hydroxyphenyl Propargyl Alcohols via -Quinone Methide through a Metal-/Catalyst-Free Conjugate Addition/Oxy-Cyclization.

A facile route to 3-sulfonylated and 3-(1-benzotriazolyl)-benzofurans is achieved from readily available -hydroxyphenyl propargyl alcohols (-HPPAs) and bench-top sodium sulfonylates and benzotriazoles with no assistance of any reagent or catalyst. Bifunctional -quinone methides (-QMs) were the putative reaction intermediates ensued from dehydration of -HPPA. Our study revealed that the -QM was so choosy in selection of the nucleophiles for the key Michael addition reaction.

Mycobacterial protein tyrosine kinase, PtkA phosphorylates PtpA at tyrosine residues and the mechanism is stalled by the novel series of inhibitors.

Phosphorylation and dephosphorylation are the key mechanisms for mycobacterial physiology and play critical roles in mycobacterial survival and in its pathogenesis. Mycobacteria evade host immune mechanism by inhibiting phagosome - lysosome fusion in which mycobacterial protein tyrosine phosphatase A (PtpA;TP) plays an indispensable role. Tyrosine kinase (PtkA;TK) activated by autophosphorylation; phosphorylates TP, which subsequently leads to increase in its phosphatase activity.

A nickel-catalyzed anti-carbometallative cyclization of alkyne-azides with organoboronic acids: synthesis of 2,3-diarylquinolines.

An anti-carbonickelative cyclization via reversible alkenylnickel E/Z isomerization of 2-azido phenyl propargyl alcohols with aryl boronic acids is achieved using Ni(acac) as the catalyst to access 2,3-diaryl quinolines. It represents a rare example of trapping the vinyl metal intermediate with a nitrogen center, a non-carbon center electrophile.

Ni-Catalyzed regio- and stereoselective addition of arylboronic acids to terminal alkynes with a directing group tether.

Addition of arylboronic acids to directing group tethered acetylenes in a regio and stereoselective manner using an inexpensive catalytic system is achieved for the first time to access highly sought after allyl/homoallyl alcohol/amine units. The apparent vinylnickel intermediate was successfully trapped by the Michael electrophiles to get defined tri- and tetra-substituted olefins. An interesting selectivity switch was observed with internal alkynes.

A direct access to isoxazoles from ynones using trimethylsilyl azide as amino surrogate under metal/catalyst free conditions.

A general method for isoxazoles from readily available ynones using trimethylsilyl azide as an amino surrogate, likely via an unprecedented hydroazidation of the alkyne and denitrogenative cyclization, is demonstrated. The method neither required any catalyst nor demanded unusual conditions to afford the products with outstanding functional group compatibility.

Synthesis of benzofuranyl and indolyl methyl azides by tandem silver-catalyzed cyclization and azidation.

Ag(i)-catalyzed synthesis of 2-azidomethyl benzofurans/indoles from linear and readily available hydroxyl/amino-phenyl propargyl alcohols is described via a highly regioselective C-O and C-N bond formation. Control experiments reveal that the reaction involves the sequential Ag(i)-catalyzed 5-exo-dig cyclization and a catalyst free γ-allylic azidation. The synthetic utility of this method has been demonstrated by using the azidomethyl unit of the above synthesized heterocycles as the base for a variety of other functionalizations, such as triazole-, tetrazole-, amide-, amine-, and pyrido-derivatives.

Hg/Pt-catalyzed conversion of bromo alkynamines/alkynols to saturated and unsaturated γ-butyrolactams/lactones via intramolecular electrophilic cyclization.

Convenient and general Hg(ii)/Pt(iv) catalyzed syntheses of γ-butyrolactams and α,β-unsaturated γ-butyrolactones/lactams are described via intramolecular electrophilic cyclizations of bromoalkynes with tosylamino and hydroxyl tethers. The reaction features the use of wet solvents, the exclusion of any base and additive, mild conditions and practical yields. We also synthesised few chiral lactams through this pathway.

Synthesis of 3-Sulfonylamino Quinolines from 1-(2-Aminophenyl) Propargyl Alcohols through a Ag(I)-Catalyzed Hydroamination, (2 + 3) Cycloaddition, and an Unusual Strain-Driven Ring Expansion.

We describe herein a silver-catalyzed conversion of 1-(2-aminophenyl)-propargyl alcohols to 4-substituted 3-tosylaminoquinolines using TsN3 as an amino surrogate. Controlled reactions reveal the pathway consisting of Ag(I)-catalyzed 5-exo-dig cyclization, catalyst-free (2 + 3) cycloaddition, and ring-expansive rearrangement via nitrogen expulsion. As a support study, we show that the cyclic enamines in similar conditions produce amidines via a C-C bond migration.

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols.

The copper-catalyzed ketenimine formation reaction of 1-(o-acetamidophenyl)propargyl alcohols with various sulfonyl azides is found to undergo a concomitant intramolecular nucleophile attack to generate 1,2-dihydro-2-iminoquinolines after aromatization (via elimination of acetyl and hydroxy groups) and tautomerization. The reaction produces 4-substituted and 3,4-unsubstituted title compounds in moderate to good yields under mild reaction conditions.

Cu-catalyzed conversion of propargyl acetates to E-α,β-unsaturated amides via ketenimine formation with sulfonyl azides.

The reaction between readily accessible propargyl acetates and sulfonyl azides in the presence of CuI catalyst yields trans-α,β-unsaturated N-tosylamides via N-sulfonyl ketenimine formation followed by a probable 1,3-OAc migration ([3,3]-sigmatropic rearrangement). The reaction is very general, allowing all kinds of substitution, including alkyl, aryl (electron-donating, -withdrawing, and -neutral), heteroaryl, and vinyl groups, on the C-terminal of acrylamide. Also, the method affords the products at ambient temperature with excellent diastereoselectivity in moderate to good yields.