A convenient ‘catch and release’ synthesis of fused 2-alkylthio-pyrimidinones mediated by polymer-bound BEMP

A robust ‘catch and release’ synthesis of fused 2-alkylthio-3-substituted-pyrimidinones mediated by the polymer-bound base P-BEMP is described. This reengineered synthesis combines the efficiency of the classical synthesis (three steps, three diversity points) with the practical benefits of resin-bound reagents. The solution-phase strategy, reagent compatibility, and the results of a representative 48-member combinatorial library are described and presented herein.     

A simple one-pot synthesis of triflyl guanidines: access to highly substituted electron-poor guanidines

Unsymmetrical di- and trisubstituted triflyl guanidines are accessed through a simple, one-pot protocol from the corresponding isothiocyanate and amine. Furthermore, in the presence of base, trisubstituted triflyl guanidines are alkylated to obtain tetrasubstituted triflyl guanidines in high yields and complete regioselectivity.     

Polymer-supported thiobenzophenone: a self-indicating traceless ‘catch and release’ linker for the synthesis of isothiocyanates

The use of a thiobenzophenone as a self-indicating linker in the polymer-supported synthesis of isothiocyanates via a traceless ‘catch and release’ strategy is reported. Isothiocyanates were furnished via 1,3-dipolar cycloaddition of nitrile oxides with the polymer-supported thiobenzophenone linker, followed by Lewis acid-assisted fragmentation of the resulting polymer-supported oxathiazole.     

Thiol on silica as a ‘catch and release’ support for isocyanates to afford ureas

Silica-bound thiocarbamates were prepared by Curtius rearrangement of carboxylic acids in the presence of thiol on silica gel. The solid supported thiocarbamates were found to be stable isocyanate equivalents, which upon treatment with amines efficiently afforded di- and tri-substituted ureas. The urea products released from the catch and release support were, in the majority of cases, greater than 95% pure and required no further work up.     

A facile and practical one-pot synthesis of multisubstituted 2-aminothiophenes via imidazole-catalyzed Gewald reaction

A simple and efficient procedure was developed for the synthesis of multisubstituted 2-aminothiophene derivatives. In the presence of catalytic amount of imidazole, ketones or aldehydes, dicyanomethane and elemental sulfur were converted into the corresponding 2-aminothiophene derivatives in moderate to high yields in DMF at 60 °C.     

A facile one-pot synthesis of N-substituted tetrahydroquinolines

An uncatalyzed one-pot synthesis of N-substituted tetrahydroquinolines was achieved in good yields by the reaction of quinoline and alkyl/acyl halides with Hantzsch dihydropyridine ester under mild reaction conditions.     

A one-pot synthesis of substituted salicylnitriles

Phenols were converted to salicylaldehydes with paraformaldehyde, MgCl₂-Et₃N in THF, and subsequent treatment with aqueous ammonia gave the corresponding imines which were oxidized with IBX to the desired salicylnitriles. The sequence of reactions was conveniently carried out as a one-pot procedure under mild conditions.     

A facile,one-pot synthesis of Ephedra-based aziridines

A series of enantiomerically and diastereomerically enriched N-sulfonylaziridines have been prepared by a single-pot process from (1R,2S)- and (1S,2R)-norephedrine and (1S,2S)-pseudonorephedrine. The cyclization process involved N-sulfonylation of the Ephedra alkaloid followed by O-sulfonylation with methanesulfonyl chloride. The bis(sulfonyl)Ephedra derivatives were treated with either hydrazine or sodium hydroxide to afford the N-sulfonylaziridines.     

A facile synthesis of substituted benzyl selenocyanates

Benzyl selenocyanates can be made from the corresponding benzylic bromides or chlorides in 30-60 minutes using acetonitrile as a solvent. The products may be obtained pure in satisfactory yields without recourse to chromatography.     

Applications of Baylis-Hillman acetates: one-pot, facile and convenient synthesis of substituted γ-lactams

A simple, convenient and one-pot transformation of the acetates of Baylis-Hillman adducts into substituted γ-lactams, that is, (E)-5-alkyl-3-arylidenepyrrolidin-2-ones via treatment with nitroalkanes in the presence of a base, followed by reductive cyclization, using Fe/AcOH, is described.     

A facile one-pot synthesis of supercubes of Pt nanocubes

A facile one-pot synthetic strategy is developed to prepare high-quality Pt supercubes. The as-synthesized Pt supercubes are composed of the uniform Pt nanocubes arranged in a primitive cubic structure. The shape and size of the Pt superparticles are readily tuned by varying the structures of pyridyl-containing ligands used in the synthesis. The co-presence of CO and nitrogen-containing ligands is critical to the formation of Pt supercubes. While CO molecules play an important role in the synthesis of Pt nanocube, introducing nitrogen-containing ligands is essential to the successful assembly of those nanocubes into Pt supercubes. Our systematic studies reveal that the electrostatic attraction between positively charged ligands and negatively charged Pt nanocubes is the main driving force for the assembly of Pt nanocubes into supercubes. More importantly, the ligands within the Pt supercubes are readily removed at relatively low temperature to yield surface-clean supercubes which are expected to exhibit unique size-selective catalysis.     

A facile one-pot synthesis of functionalized thiazines in water

An efficient synthesis of thiazines from the three component reactions between dialkyl acetylenedicarboxylates,arylisothio-cyanates and iV-nucleophiles at room temperature in water as the solvent is described.     

A novel one-pot synthesis of substituted 4-t-butyldimethylsilyloxy-thiazoles

The reaction of 2-halo-acylimidazolides or halides with primary thioamides in base give 2-halo-N-acylthioamides, which cyclize to the substituted 4-thiazolones and are trapped as the novel 4-t-butyldimethylsilyloxythiazoles in fair to good yield. The 2-aryl-4-t-butyldimethylsilyloxythiazoles undergo a [4+2] cycloaddition reaction with dimethoxyacetylene dicarboxylate [DMAD] to give substituted 2-pyridones in fair yield.     

A facile synthesis of some substituted furopyrimidine derivatives

Some substituted furopyrimidine derivatives are prepared in high yield in 4 steps, starting from the reaction of furoin (1,2‐di(furan‐2‐yl)‐2‐hydroxyethanone) and malonitrile.     

A practical one-pot synthesis of vinylstannanes from ketones

Treatment of ketones with Bu3SnLi followed by addition of MsCl/Et3N to the resulting alkoxide provides vinylstannanes. Cyclic vinylstannanes are particularly amenable to this procedure and isolated yields of 81-83% could be consistently attained. Traces of Bu3SnH in crude reaction products could be removed by stirring in CHCl3 with a catalytic amount of AIBN followed by filtration through silica gel.     

A practical, one-pot synthesis of sulfonylated pyridines

A concise and efficient one-pot synthesis of functionalized sulfonylated pyridines via an S(N)Ar reaction of readily available pyridines and sodium sulfinate salts in the presence of tetrabutylammonium chloride is presented.     

Efficient one-pot synthesis of substituted pyrazoles

An efficient, one-pot synthesis of substituted pyrazoles from enones, hydrazides, and halides was developed. In comparison with the classical Knorr pyrazole synthesis, this methodology gave a different type of product (R³≥R⁵). A range of substituted pyrazoles were prepared in good to high yields with complete regioselectivity.     

A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

A practical one-pot synthesis of enantiopure unsymmetrical salen ligands

A practical, one-pot synthesis of enantiopure unsymmetrical salen ligands is described, using a 1:1:1 molar ratio of a chiral diamine and two different salicylaldehydes. The new synthetic protocol can be readily performed in good yields (60-85%) on a multigram scale with good tolerance toward various functional groups.