Effect of metal ions in organic synthesis. Part XXXI. Synthesis of new 3-carbonyl- and 3-carboxy-1-heterocyclaminopyrroles by copper(II) chloride-catalyzed reaction of heterocyclic azoalkenes

The direct synthesis of a new class of unknown 1-heterocyclamino-3-carbonylpyrroles and 1-heterocyclamino-3-carboxypyrroles by copper(II) chloride-catalyzed reaction of heterocyclic conjugated azoalkene derivatives with β-diketones and β-ketoesters is reported.     

Facile synthesis of 3-trimethylsilylindazoles by [3+2]cycloaddition reaction of lithium trimethylsilyldiazomethane with benzynes

[3+2]Cycloaddition reaction of lithium trimethylsilyldiazomethane with benzynes, generated from halobenzenes, gave the corresponding 3-trimethylsilylindazoles in good to moderate yields.     

N-quaternary compounds. Part LIX. Facile synthesis of 3-vinyl-4(3H)-pyrimidinethiones

3-Vinyl derivatives of 4(3H)-pyrimidinethiones have been prepared from 2,3-dihydrothiazolo[3,2-c]pyrimidinium derivatives through ring-opening by a strong base such as potassium t-butoxide in DMF. The pyrimidinium derivative is initially prepared from 4(3H)-pyrimidinethiones. 3-Vinyl-4(3H)-pyrimidinethiones are also formed by the ready decarboxylation of 2,3-dihydrothiazolo[3,2-c]pyrimidinium-3-carboxylates. In the mass spectrometer the nature of the volatile species was elucidated by means of appearance potentials and fragmentation patterns.     

Facile synthesis of sulfur-substituted allenes by a three-component reaction

The three-component reaction of lithium alkylthiolate, 1-alkynylphosphine oxide and aldehyde in THF affords sulfur-substituted allenes in good to excellent yield.     

Condensed 1,3-benzothiazinones. 1. Facile synthesis of 2-amino-1,2,4-triazolo[5,1-b][1,3]-benzothiazin-9-one

Treating 2-mercaptobenzohydrazide ( 1a ) with cyanogen bromide gave 3-amino-2-imino-3,4-dihydro-2.H-1,3-benzothiazin-4-one ( 2a ). This compound underwent further cyclocondensation with a second molecule of cyanogen bromide or S-methylisothiourea sulfate to afford the biologically interesting 2-amino-1,2,4-triazolo-[5,1-b][1,3]benzothiazin-9-one ( 3c ). Compound 3c could also be prepared directly from 1a by treating with excess amount of cyanogen bromide in more satisfactory yield.     

Facile and selective synthesis of chloronicotinaldehydes by the Vilsmeier reaction

Eleven enamides were prepared by adopting different procedures. The various enamides prepared were subjected to Vilsmeier reaction using (i) POCl₃/DMF; (ii) diphosgene/DMF; (iii) triphosgene/DMF leading to the formation of various multisubstituted chloronicotinaldehydes. Studies carried out indicate that Vilsmeier reagent concentration and the replacement of POCl₃ by diphosgene or triphosgene, provides excellent selectivity and higher yields. Under modified reaction conditions one can get only chloronicotinaldehydes and not the chloropyridines as products. The various advantages in using diphosgene and triphosgene are illustrated. The mechanism of formation of chloronicotinaldehyde was discussed.     

Facile synthesis of aminonaphthoquinone Mannich bases by noncatalytic multicomponent reaction

Mannich bases are formed in a noncatalytic multicomponent reaction, which is promoted by ultrasound irradiation. The procedure avoids the use of toxic solvents, catalyst, and purification, generating the desired compounds in excellent yields and short reaction times.     

Facile synthesis of 1,3-diacetyl-2-methylcyclopentene a versatile synthetic intermediate.

Convenient access to 1,3-diacetyl-2-methylcyclopentene $\text{2}$ is reported by three routes: acetylation of methylcyclopentene ( or cyclohexane), condensation of acetylacetone with 1,2-dibromoethane, and the isomerisation of O-acrtylated dienolate of 1-actyl-2-methylcyclopentene. The process of isomerisation provides best results and its mechanism is discussed.     

Aminobutadienes. V. Polymers of 1-phthalimido-1,3-butadiene and 1-succinimido-1,3-butadiene

The radical polymerizations of 1-phthalimido-1,3-butadiene (1-PB) and 1-succinimido-1,3-butadiene (1-SB) were carried out in bulk and in solution. The polymers obtained had reduced viscosities in the ranges of 1.0–4.0 (1-PB) and 0.2–0.6 (1-SB). Both polymers had a similar softening point of 190–200°C. The radical polymerization of 1-phthalimido-1,3-butadiene clearly showed a tendency to give crosslinked polymer. Steric arguments about these polymer structures as a result of the infrared and ozonolysis data led to the conclusion that these polymers contained approximately 20% of the 3,4 form but no 1,2 configuration, and, therefore, that the 1,4 addition was preferred.     

Facile synthesis of a 4-anilinoquinazoline dimer by Suzuki cross-coupling reaction

A novel 4-anilinoquinazoline dimer linked by a carbon-carbon bond in the C-7 position was synthesized via a one step Suzuki cross-coupling reaction. All structures of new compounds were characterized by ¹H NMR, ¹³C NMR, and HRMS. The inhibition rate of the synthetic 4-anilinoquinazoline dimer 8 against epidermal growth factor receptor-tyrosine kinase enzymes (EGFR) in vitro was 44.4% at the concentration of 5.5 μmol/L.     

Facile synthesis of new oxalate dimers of naturally occurring 3-hydroxysteroids

Several symmetrical steroidal oxalate dimers were synthesised from naturally occurring 3-hydroxysteroids, namely, estrone (1), DHEA (3), pregnenolone (5), cholesterol (7), 5D-cholestane (9), and stigmasterol (11), using oxalyl chloride. Full spectroscopic data for all the new compounds are presented. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 442–444, September–October, 2006.     

Facile synthesis of complicated 9,9-diarylfluorenes based on BF3.Et2O-mediated Friedel-Crafts reaction

[reaction: see text] BF3.OEt2-mediated Friedel-Crafts reaction of 9-phenyl-fluoren-9-ol with electron-rich aromatic substrates to prepare a new family of complicated 9,9-diarylfluorenes is described. The 9,9-diarylfluorenes tethered with various functional substituents, e.g., bulky spiro units, hole-transporting moieties, and fluorescent dyes, will be promising building blocks for the construction of optoelectronic materials.     

Studies on the synthesis of heterocyclic compounds. Part V. A novel synthesis of some pyridazin-4-(1H)one derivatives and their reaction with hydrazine

Some phenylazo derivatives of β-dicarbonyl compounds 1a,b,c,d reacted with dimethylformamide dimethylacetal to yield new 1-phenyl-3-R-4-(1H)pyridazinones 3a,e and 4. When compounds 3a and 3e were treated with hydrazine hydrate, they gave rise to pyrazolo[4,3-c]pyridazines 5 and 7 , respectively. By the action of hydrazine hydrate on compound 4 , the 1-phenyl-3-(1H-pyrazol-3-yl)-4-(1H)pyridazinone 8 was obtained. The structures of all the new compounds were assigned on the basis of satisfactory analytical and spectroscopic data.     

Facile and highly diastereoselective synthesis of 3-aminooxindoles via AgOAc-catalyzed vinylogous Mannich reaction

A novel AgOAc-catalyzed vinylogous Mannich reaction between easily prepared imines 1 derived from isatins and trimethylsilyloxyfuran 2 (TMSOF) was developed. This method provided a facile synthetic route to get access to synthetically useful quaternary 3-aminooxindole in excellent yields (94–99%) and diastereoselectivities (>99:1).     

Facile synthesis of optically active oxindoles by copper-catalyzed asymmetric monotosylation of prochiral 1,3-diols

A facile synthetic method toward optically active 3,3-disubstituted oxindoles with excellent enantioselectivity was achieved using chiral copper-catalyzed desymmetrization of prochiral 1,3-diols. The monotosylated product was transformed into oxindole derivatives efficiently.     

Palladium/nickel-cocatalyzed cycloaddition of 1,3-dehydro-o-carborane with alkynes. Facile synthesis of C,B-substituted carboranes

o-Carboryne (1,2-dehydro-o-carborane) has been reported as a very reactive intermediate and regarded as a three-dimensional relative of benzyne, whereas the 1,3-dehydro-o-carborane has remained elusive. In this article, we present the preparation of 1,3-dehydro-o-carborane from 3-iodo-1-lithio-o-carborane mediated by palladium(0). This reactive intermediate can be trapped by alkynes via Pd/Ni-cocatalyzed [2 + 2 + 2] cycloaddition reaction, leading to the formation of C,B-substituted-o-carborane derivatives. The possible reaction mechanism involving the formation of metal-1,3-dehydro-o-carborane followed by stepwise insertions of 2 equiv of alkyne and reductive elimination is proposed, and the relative reactivity of M-C versus M-B bond in metal-1,3-dehydro-o-carborane complexes is also discussed. This work offers a new methodology for B-functionalization of carboranes and demonstrates that metal-1,3-dehydro-o-carborane can be viewed as a new kind of boron nucleophile.     

Facile synthesis of functional polyperoxides by radical alternating copolymerization of 1,3‐dienes with oxygen

We have developed a facile synthesis of degradable polyperoxides by the radical alternating copolymerization of 1,3‐diene monomers with molecular oxygen at an atmospheric pressure. In this review, the synthesis, the degradation behavior, and the applications of functional polyperoxides are summarized. The alkyl sorbates as the conjugated 1,3‐dienes gave a regiospecific alternating copolymer by exclusive 5,4‐addition during polymerization and the resulting polyperoxides decomposed by the homolysis of a peroxy linkage followed by successive β‐scissions. The preference of 5,4‐addition was well rationalized by theoretical calculations. The degradation of the polyperoxides occurred with various stimuli, such as heating, UV irradiation, a redox reaction with amines, and an enzyme reaction. The various functional polyperoxides were synthesized by following two methods, one is the direct copolymerization of functional 1,3‐dienes, and the other is the functionalization of the precursor polyperoxides. Water soluble polyperoxides were also prepared, and the LCST behavior and the application to a drug carrier in the drug delivery system were investigated. In order to design various types of degradable polymers and gels we developed a method for the introduction of dienyl groups into the precursor polymers. The resulting dienyl‐functionalized polymers were used for the degradable gels. The degradable branched copolymers showed a microphase‐separated structure, which changed owing to the degradation of the polyperoxide segments. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000–000; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900009