Copper-catalyzed direct benzylation or allylation of 1,3-azoles with N-tosylhydrazones

Cu-catalyzed cross-coupling of N-tosylhydrazones with 1,3-azoles leads to the direct C-H benzylation or allylation. Cu carbene migratory insertion is proposed to play the key role in this transformation.     

Copper-mediated and copper-catalyzed cross-coupling of indoles and 1,3-azoles: double C-H activation

A new bronze age: the described copper-mediated cross-coupling with double C-H activation can provide a convergent access to indole-containing biheteroaryls that are of high interest in pharmaceutical and medicinal chemistry. In this strategy an easily attachable and detachable 2-pyrimidyl directing group is used. Moreover, a variant that is catalytic in copper is achieved by using atmospheric oxygen as an ideal co-oxidant.     

Ring-expansion polycondensation of 2-stanna-1,3-dioxepane (or 1,3-dioxepene) with dicarboxylic acid chlorides

2,2-Dibutyl-2-stanna-1,3-dioxepane 1 (or 1,3-dioxepene 2) were prepared from 1,4-butane (or 1,4-butene) diol and dibutyltin dimethoxide. They were polycondensed at 80°C in n-heptane with adipoyl-, suberoyl, sabacoyl chloride and with decane-1,10-dicarbonyl chloride. In the case of suberoyl chloride and 2,2-dibutyl-2-stanna-1,3-dioxepane reaction time, temperature and stoichiometry were varied to optimize both the molecular weight and the fraction of cyclic polyesters. With a slight excess of the dicarboxylic acid chlorides, only macrocyclic polyesters were obtained in all cases. The resulting cyclic polyesters were characterized by viscosity measurements, by ¹H and ¹³C NMR and by MALDI-TOF mass spectrometry.     

An unusual hydrogen addition of indolo-2,3-quinodimethanes to dimethylindoles in the presence of 1,3-azoles

Indolo-2,3-quinodimethane generatedin situ frombis-(bromomethyl)indole with NaI/DMF at 70°C was expected to undergo cycloaddition with 1,3-azoles to give carboline derivatives, which form the backbone of many indole alkaloids. However, the reaction did not give the anticipated product but proceeded via hydrogen addition to exocyclic methylene groups, furnishing dimethylindoles in good yields     

Cycloaddition reactions of 1,3-benzothiazines - 6. Reactions of 1,3-benzothiazine derivatives with substituted acetyl chlorides

6, 7-Dimethoxy-2$\text{H}$-l,3-benzothiazine derivatives ($\text{1}$, $\text{8}$) react with substituted acetyl chlorides to give angularly condensed β -lactams ($\text{3a}$-$\text{d}$, $\text{10}$, $\text{11}$). The $\text{cis}$ compound $\text{11}$ was epimerised to the $\text{trans}$ derivative $\text{12}$. From the interaction of 2-phenyl-6,7-dimethoxy-4$\text{H}$-1,3-benzothiazine ($\text{7}$) and α -chloro-phenylacetyl chloride two stereoisomeric β -lactam derivatives ($\text{9a}$, $\text{b}$) were isolated, whereas in the other cases studied the reactions leading to β -lactams proved to be stereospecific. Analogous reactions of $\text{4}$-methyl-6,7-dimethoxy-2$\text{H}$-l,3-benzothiazine ($\text{5}$) furnished the enamides $\text{6a}$,$\text{c}$, $\text{d}$. Structures of the new compounds and configurations of the diastereomers were elucidated by IR and NMR spectroscopy.     

Versatile access to C-4-substituted 2-amino-1,3-azoles from hydropyridines in oxidative conditions

[Chemical reaction: see text] Various substituted 2-aminotetrahydroazolopyridines and 2-aminohexahydroazolopyridines have been prepared by bromine-mediated addition of protected guanidine or urea to hydropyridine derivatives. The pH-dependent regioselective cleavage of the resulting aminal function led to the 2-aminoazole products III. The yields of the bicycles of type II, and their conversion into azoles III depends on the electronic properties of the substituents on the nitrogen of the tetrahydopyridine.     

Interaction of 2-aryl-4-cyano-1,3-oxazole-5-sulfonyl chlorides with amidines

Reaction of 4-cyano-1,3-oxazole-5-sulfonyl chlorides with amidines results in new 7-amino-1,3-oxazolo[5,4-d]pyrimidines. Their structure was confirmed by spectral methods and X-ray diffraction analysis.     

N-H Insertion reactions of rhodium carbenoids. Part 5: A convenient route to 1,3-azoles

Dirhodium(II) carboxylate catalysed reaction of diazocarbonyl compounds 2 in the presence of primary amides 1 results in the formation of α-acylaminoketones 3 (12 examples) by N-H insertion reaction of the intermediate rhodium carbene. The 1,4-dicarbonyl compounds 3 are readily converted into structurally diverse oxazoles 4 (11 examples) by cyclodehydration, thiazoles 5 (10 examples) by treatment with Lawesson's reagent, or imidazoles 6 (2 examples) by reaction with ammonia or methylamine.     

Synthesis of 1,3-dialkylimidazolium-2-carboxylates by direct carboxylation of 1,3-dialkylimidazolium chlorides with CO2

1,3-Dialkylimidazolium-2-carboxylates 1a and 1b are obtained in good to excellent yield and selectivity by carboxylation of the corresponding 1,3-dialkylimidazolium chloride salts with a CO₂/Na₂CO₃ system at temperatures ranging from 80 to 135 °C. The effect of temperature and reaction time on the yield and the selectivity of the carboxylation products has been studied. Coupling the CO₂-based synthesis of 1,3-dialkylimidazolium-2-carboxylates with the transcarboxylation reaction described earlier [Tommasi, I.; Sorrentino, F.; Tetrahedron Lett., 2005, 46, 2141] allows us to set up a new synthetic procedure for the synthesis of organic carboxylates and alkylcarbonate anions avoiding the use of strong bases.     

Observation of 1,3-diketones formation in the reaction of bulky acyl chlorides with methyllithium

The formation of 1,3-diketones was observed in the reactions of bulky acyl chlorides with methyllithium. The reaction products depend on the steric hindrance around the carbonyl group of the acyl chloride and the electronic effect of the group(s) linked to the carbonyl. When the steric hindrance around the carbonyl group of the acyl chloride is big enough, the 1,3-diketone is the only product. In the case of the moderate hindrance around the carbonyl group of the acyl chloride, a moderate yield of 1,3-diketone is obtained and some tertiary alcohol is generated. When there is no steric hindrance around the carbonyl group of the acyl chloride, the tertiary alcohol is the only product. When the steric hindrance around the carbonyl group is moderate and an electron-donating group is connected to the carbonyl of the acyl chloride, all three products--ketone, 1,3-diketone and tertiary alcohol--can be isolated from the reaction mixture after long reaction times.     

Synthesis of C3-Symmetric star-shaped molecules containing 1,3-azoles via hetero-aryl Heck coupling

We have demonstrated a useful synthetic strategy to assemble star-shaped C₃-symmetric molecules containing 1,3-azole moieties at the periphery. To generate these C₃-symmetric heterocycles, we have employed the Pd/Cu-based coupling reactions. To this end, we have used benzoxazole, benzothiazole, and benzimidazole as coupling partners to generate the corresponding hetero-aryl Heck coupling products.     

Synthesis of higher 1,3-diols from ethylene and carboxylic acid chlorides

Conclusions A new method was developed for obtaining the higher 1,3-diols, which is based on the use of carboxylic acid chlorides and ethylene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 909–911, April, 1981.     

Regioselective synthesis of functionalized 3,5-diketoesters and 2,4-diketosulfones by uncatalyzed condensation of 1-methoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha,beta-unsaturated acid chlorides and sulfonyl chlorides

The reaction of 1-methoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha,beta-unsaturated and functionalized acid chlorides afforded a variety of 3,5-diketoesters which are not readily available by other methods. The reaction of 1-methoxy-1,3-bis(trimethylsilyloxy)-1,3-butadiene with sulfonyl chlorides allows a direct synthesis of 2,4-diketosulfones.     

Chemo-, regio-, and stereoselective cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha-chloroacetic acid chlorides and alpha-chloroacetic acetals

Treatment of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha-chlorocarboxylic acid chlorides resulted in chemo- and regioselective formation of 6-chloro3,5-dioxo esters, which were regioselectively converted into functionalised 3(2H)furanones. Chemo- and regioselective condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha-chloroacetic dimethyl acetal afforded 6-chloro-5-methoxy-3-oxo esters, which could be regio- and stereoselectively transformed into 2-alkylidene-4-methoxytetrahydrofurans.     

Amidophenacylating reagents in synthesis of new derivatives of 1,3-oxazole- and 1,3-thiazole-4-sulfonyl chlorides and corresponding sulfonamides

Derivatives of 4-benzylsulfanyl-1,3-oxazole and 4-benzylsulfanyl-1,3-thiazole were synthesized using available amidophenacylating reagents. By the oxidative chlorination compounds obtained were converted to 1,3-oxazole-4-sulfonyl and 1,3-thiazol-4-sulfonyl chlorides. The latter were used to prepare the corresponding sulfonamides.     

Synthesis of 1,3,5-tricarbonyl derivatives by condensation of 1,3-bis(silyl enol ethers) with acid chlorides

A variety of 1,3,5-tricarbonyl derivatives were prepared by reaction of 1,3-bis(silyl enol ethers) with acid chlorides under mild conditions. This includes reactions of both aromatic and aliphatic acid chlorides and bis(acid chlorides). The yields vary depending on the type of acid chloride employed.     

Synthesis of 2-aryl-4-cyano-1,3-oxazole-5-sulfonyl chlorides and N-substituted sulfonamides

Oxidative chlorination of 2-aryl-5-benzylsulfanyl-1,3-oxazole-4-carbonitrile results in the previously unknown 4-cyano-1,3-oxazole-5-sulfonyl chlorides and N-substituted sulfonamides.     

Fluorinated 2-benzoylcyclohexane-1,3-diones and their vinylogous acyl chlorides in the reactions with primary and secondary amines

The reaction of 5,5-dimethyl-2-[(3-fluoro- and 4-fluoro)benzoyl]cyclohexane-1,3-diones with primary and secondary amines affords their exocyclic enamine derivatives. Under similar conditions 5,5-dimethyl-2-(2-fluorobenzoyl)]cyclohexane-1,3-dione undergoes dehydrofluorination and intramolecular cyclization to give 3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthene-1,9-dione. The reaction of vinylogous substitution of the enol derivatives of the fluorinated 5,5-dimethyl-2-benzoylcyclohexane-1,3-diones (vinylogous acyl chlorides) with amines results in the formation of the endocyclic enaminoderivatives.     

Cycloaddition reactions of 1,3-benzothiazines—I. : Reactions of 2-phenyl-4-H and 4-phenyl-2H-1,3-benzothiazine derivatives with substituted acetyl chlorides

6,7-Dimethoxy-2-phenyl-4$\text{H}$-1,3-benzothiazine (1) and 6,7-dimethoxy-4-phenyl-2$\text{H}$-1,3-benzothiazine (2) react with substituted acetyl chlorides to give linearly, and new angularly condensed β-lactam derivatives (4,5). Heating of the latter compounds with hydrogen chloride in anhydrous ethanol leads to the formation of the corresponding 4$\text{H}$- and 2$\text{H}$-1,3-benzothiazinium chloride, respectively. The configurations of these compounds (the mutual positions of the substituents relative to the β-lactam ring) were determined by ¹H and ¹³C studies, also making use of the aromatic solvent-induced shifts.     

Studies on the palladium-catalysed direct alkenylation of 1,2-azoles

Electron-rich isoxazoles, isothiazoles and pyrazoles undergo palladium-catalysed direct alkenylation in moderate yields.