Comparative Studies on the Behavior of 3-Amino-2-phenyl-4(3<Emphasis Type="Italic">H</Emphasis>)-quinazolinone Towards Some Organophosphorus Reagents

Summary. The reaction of 3-amino-2-phenyl-4(3H)-quinazolinone with oxovinylidenetriphenylphosphorane afforded 5-phenylpyrazolo[1,5-c] quinazoline-2(3H)-one and triphenylphosphine oxide. On the other hand, when quinazolinone reacts with phosphorus ylides, the corresponding phosphorane adducts were obtained. Moreover, quinazolinone reacts with trisdialkylaminophosphines to give the new (dialkylamino)oxophosphonium dipolar products. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Comparative Studies on the Behavior of 3-Amino-2-phenyl-4(3 H )-quinazolinone Towards Some Organophosphorus Reagents

The reaction of 3-amino-2-phenyl-4(3H)-quinazolinone with oxovinylidenetriphenylphosphorane afforded 5-phenylpyrazolo[1,5-c] quinazoline-2(3H)-one and triphenylphosphine oxide. On the other hand, when quinazolinone reacts with phosphorus ylides, the corresponding phosphorane adducts were obtained. Moreover, quinazolinone reacts with trisdialkylaminophosphines to give the new (dialkylamino)oxophosphonium dipolar products. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Chemistry of Phosphorus Ylides. Part 22 [1]. Effect of Newly Synthesized Niclosamide Mannich Bases,Phosphopyranones, Phosphoranylidenes,and Oxaphosphinin on Some Metabolic Aspects of <Emphasis Type="Italic">Biomphalaria Alexandrina</Emphasis>

Summary. Niclosamide reacts with secondary amines and formaldehyde under the condition of Mannich reaction, to give new Mannich bases. The reaction of these niclosamide Mannich bases with active phosphacumulene ylides affords the corresponding phenyliminopyranone, pyranone, and pyranthione, respectively. When Wittig reaction was carried out on the pyranone, using p-nitrobenzaldehyde, a new arylidene and triphenylphosphine oxide were obtained. On the other hand, stabilized phosphonium ylides affect the transylidation of niclosamide Mannich bases to the corresponding phosphoranylidenes. When diphenylmethylenetriphenylphosphorane reacts with a niclosamide Mannich base, an oxaphosphinin was obtained. The molluscicidal potency of the newly synthesized derivatives against Biomphalaria alexandrina was studied, too.     

Studies on Phosphonium Ylides XXV: The Behavior of Active Phosphacumulene and Stabilized Alkylidenephosphoranes Towards 5-(4H)-Oxazolones

The reaction of 2-phenyl-5-(4H)-oxazolone 1 and its 4-benzylidene derivative 2 with oxovinylidenetriphenylphosphorane 3 afforded 2-phenylfuro [3,2-d] [1,3]oxazol-5-(6H)-one 6 and 2,7-diphenyl-5H-pyrano[3,2-d][1,3]oxazol-5-one 7 along with triphenylphosphine. Alternatively, when 2-phenyl-5-(4H)-oxazolone 1 reacts with phosphorus ylides 4a–f the corresponding new phosphorane, the cyclic and/or the olefinic adducts were obtained. Moreover, oxazolone reacts with N-(triphenylphosphoranylidene)aniline 5 to give the new imino product 14 together with triphenylphosphine oxide. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results. Biological evaluations of the new products are also studied.     

Synthesis and Mechanistic Study of Triheterocyclic 4H‐Pyrimido[2,1‐b]benzothiazole derivatives,One‐Pot Three‐component Reaction under Solvent‐Free Conditions

An efficient method has been developed for the preparation of 4H‐pyrimido[2,1‐b]benzothiazole derivatives by the condensation of aldehydes, β‐ketoester, and 2‐amino benzothiazole under solvent and solvent‐free conditions using various catalysts. The reaction uses benzothiazole as a new component, and good yield is obtained at 60–65°C under solvent‐free conditions. Atom economies, good yield, environmentally benign, and easy to work‐up are some of the important features of this protocol. The present study suggests that acetic acid and metal catalysts follow different mechanism. In acetic acid, 2‐amino benzothiazole reacts with benzaldehyde, and resultant intermediate reacts with ethyl acetoacetate to give final product, whereas in the presence of metal catalysts, 2‐amino benzothiazole first reacts with ethyl acetoacetate, and resultant intermediate reacts with benzaldehyde to give pyrimido[2,1‐b]benzothiazole.     

o-Phenylenediamine as a New Catalyst in the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens – A Reinvestigation

Summary. In contrast to a previous report, o-phenylenediamine is not a catalyst in the ring opening reaction of epoxides by means of bromine or iodine. The o-phenylenediamine is just a reactant which reacts with iodine to give phenazine-2,3-diamine and hydrogen iodide, or with bromine to give a mixture of brominated and polymerized products as well as hydrogen bromide. The hydrogen halogenides are in fact the real epoxide ring opening reactants.     

Reaction of gem-nitronitroso-compounds with triethyl phosphite

2-Nitro-2-nitrosopropane reacts with triethyl phosphite by deoxygenation of the nitroso- group to give 2-nitriminopropane; 1-nitro-1-nitrosocyclohexane reacts similarly. The reaction proceedsvia an intermediate detectable byNMR; possible structures for this intermediate and for the course of the reaction are discussed. Some reactions of nitrimines are also reported.     

The Reaction of Biadamantylidene with Singlet Oxygen in the Presence of Dyes [1]

Singlet oxygen, generated chemically or photogenetically, reacts with biadamantylidene to give the corresponding dioxetane and epoxide only. When methylene blue (MB) or meso-tetraphenylporphin (m-TPP) is used as sensitizer the normal reaction course occurs giving dioxetane as the preponderant product in 2-propanol, ethyl acetate, acetone, pinacolone, methylene chloride, chloroform, carbon tetrachloride and benzene, although in the last two solvents some 10–25% of epoxide is formed. When erythrosin and rose bengal (RB) are used, epoxide becomes the main product (70–95%). Epoxide does not derive from chemical reaction with the solvent. Pinacolone, for example, is not oxidized to t-butyl acetate. The rose bengal reaction involves both singlet oxygen and radicals, since diazabicyclooctane (DABCO) and di-t-butyl-p-cresol interfere with the oxidation. A mechanistic scheme is proposed in which sensitizer and oxygen combine to produce sensitizer radical cation and superoxide radical anion. Subsequently, hydroperoxy radical, deriving from superoxide, reacts with substrate to give epoxide and hydroxy radicals. The latter adds to substrate to give a new radical which captures triplet oxygen. Epoxide is formed by loss of hydroperoxy radical and the chain starts anew. The dioxetane is formed separately either by [2+2]-cycloaddition or stepwise addition.     

Reactions of 3-hydrazino-5,6-diphenyl-1,2,4-triazine with 4-arylidene-2-phenyl-5(4H)-oxazolones and 4-benzylidene-3-methyl-5(4H)-isoxazolone

3-Hydrazino-5,6-diphenyl-1,2,4-triazine reacts with 4-arylidene-2-phenyl-5(4H)-oxazolones in toluene to give substituted acrylic acid hydrazides, and in glacial acetic acid to give substituted imidazolones. On the other hand the hydrazinotriazine reacts with 4-benzylidene-3-methyl-5(4H)-isoxazolone, probably via a 1,4 addition reaction followed by an elimination reaction, to give benzaldehyde 5,6-diphenyl-1,2,4-triazin-3-ylhydrazone and 3-methyl-5(4H)-isoxazolone.     

Reactions of 2-aminopyridine with picryl halides

2-Aminopyridine reacts with picryl halides to give mixtures of 1-picryl-2-(N-picrylimino)-1,2-dihydropyridine and 2-(N-picrylamino)pyridine. When picryl fluoride is treated with an excess of 2-aminopyridine, the 1-picryl-2-(N-picrylimino)-1,2-dihydropyridine reacts further with 2-aminopyridine to yield two molecules of 2-(N-picrylamino)pyridine in a reaction catalyzed by the by-product, hydrogen fluoride. In contrast, the compositions of the mixtures obtained from the reactions of picryl chloride and picryl bromide with excess 2-aminopyridine are stable in their reaction media.     

Synthesis and reactions of 2H-Benzothieno[3,2-d][1,3]oxazine-2,4(1H)-dione

The title compound 5 is synthesized by the reaction of the potassium salt of 3-aminobenzo[b]thiophene-2-carboxylic acid with phosgene. Compound 5 is readily alkylated to give 6 with methyl iodide, benzyl bromide, or propargyl bromide in the presence of sodium hydride. Reaction of 5 and 6 with nucleophiles follows specifically different pathways. Compound 5 is readily ionized to the isocycanate species 13 and subsequently reacts with methanol or methylamine to produce exclusively the carbamate 7 or ureido acid 9 . The N-substituted derivative 6 , in analogous reactions with methanol or methylamine, produce exclusively the amino ester 8 or the amino amide 10 . The N-benzyl derivative 6b reacts with the cyclic S-methylthiopseudourea 11 to give the tetracycle 12 , a new ring system.     

Studies on the chemistry of 2,3,5,6-tetrahydro-6-phenylimidazo[2,l-b]-thiazole. III. . Reaction with isocyanates and isothiocyanates

2,3,5,6-Tetrahydro-b-phenylimidazo[2,l-b-]thiazole reacts with aryl isothiocyanates to give dipolar 1:1 adducts. The adducts are relatively unstable and, in solution, exist in equilibrium with starting materials. The reaction with aryl and alkyl isocyanates, however, leads to cyclic 2:1 adducts, while sulphonyl and acyl isocyanates give stable dipolar 1:1 adducts. J. Chem. Soc., 14, 989 (1977)     

The reaction of α-haloketones with N-alkyl benzothiazolium salts

Phenacyl chloride ( 1a ) reacts with the 3-methylbenzothiazolium quaternary salt ( 2 ) to give 4-methyl-2-benzoyl-4H-1,4-benzothiazine ( 4a ). A mechanism is discussed. Secondary α-haloketones give benzothiazolines. Merocyanine dyes are formed by the reaction of 2 with carbanions. It is shown that 2 functions as a hydride ion abstractor in the formation of merocyanine dyes.     

Synthesis of Halomethyl Derivatives of 3- and 4-(Dialkoxyphosphorylmethyl)-5-tert-butylfuran-2-carboxylic Acid and Their Reactions with Nucleophilic Agents

5-tert-Butyl-4-chloromethyl-, 5-tert-butyl-4-(diethoxyphosphorylmethyl)-3-methylfuran-2-carboxylates are effectively brominated with N-bromosuccinimide by the 3-methyl group. The bis(halomethyl)derivative is phosphorylated under conditions of the Arbuzov reaction to give the corresponding chloromethylphosphonate. The obtained organophosphorus derivatives of bromomethyl- and chloromethylfuran-2-carboxylic acid react with secondary amines and sodium butanethiolate to form the corresponding substitution products. Alkyl 5-tert-butyl-4-chloromethyl-3-(diethoxyphosphorylmethyl)-furan-2-carboxylate reacts with sodium acetate in acetic acid to give a 4-acetoxymethyl derivative. It is the first example of a facile reaction with O-nucleophiles of halomethyl derivatives of phosphonomethylated furans.     

The Reaction of Maleic and Phthalic Anhydrides with 2-Methylimidazole

The reaction of maleic anhydride with 2-methylimidazole in acetonitrile and DMF is accompanied by the appearance of strong absorption bands in the visible part of the spectrum due to the formation of molecular complexes. In acetonitrile the reaction proceeds by two routes via the formation of an amide and the molecular complex. Phthalic anhydride reacts with 2-methylimidazole to give amide but not to form molecular complexes.     

Chemistry of Phosphorus Ylides. Part 22 [1]. Effect of Newly Synthesized Niclosamide Mannich Bases, Phosphopyranones, Phosphoranylidenes, and Oxaphosphinin on Some Metabolic Aspects of Biomphalaria Alexandrina

Niclosamide reacts with secondary amines and formaldehyde under the condition of Mannich reaction, to give new Mannich bases. The reaction of these niclosamide Mannich bases with active phosphacumulene ylides affords the corresponding phenyliminopyranone, pyranone, and pyranthione, respectively. When Wittig reaction was carried out on the pyranone, using p-nitrobenzaldehyde, a new arylidene and triphenylphosphine oxide were obtained. On the other hand, stabilized phosphonium ylides affect the transylidation of niclosamide Mannich bases to the corresponding phosphoranylidenes. When diphenylmethylenetriphenylphosphorane reacts with a niclosamide Mannich base, an oxaphosphinin was obtained. The molluscicidal potency of the newly synthesized derivatives against Biomphalaria alexandrina was studied, too.     

Reactions of Trisdialkylaminophosphines with Acrylohydrazide and Imidazolinone Derivatives for the Synthesis of New Organophosphorus Derivatives

Trisdimethylaminophosphine reacts with 2-benzamido-N-arylidene-3-aryl-acrylohydrazide to give phosphoryl benzamide and phosphoryl-cyano-benzamide adducts depending on the reaction conditions. Moreover, 1-aryliden-amino-2-phenyl-4-aryliden-2-imidazolin-5-ones react with trisdialkylaminophosphines to yield tetraalkylphosphonic diamide adducts. Possible reaction mechanisms are considered, and the structural assignments are based on analytical and spectroscopic evidence and X-ray analysis.     

Reactions of phosphite esters and trisdialkylaminophosphines with 5‐substituted 1,3,4‐thiadiazol derivatives

5‐{[(1E)‐(4‐methoxyphenyl)methylene]amino}‐1,3,4‐thiadiazole‐2‐thiol ( 1a ) reacts with trialkyl phosphites ( 2a–c ) to give the respective dialkyl phosphonate adducts ( 4a–c ). On the other hand, the reactions of trisdialkylaminophosphines ( 3a,b ) with 1a , 5‐{[(1E)‐(4‐phenyl)methylene]amino}‐1,3,4‐thiadiazole‐2‐thiol ( 1b ) yield the corresponding open dipolar structures 6a–c . In the case of the reaction of triethyl phosphite ( 2a ) with 1b , both the dialkyl phosphonate adduct ( 7 ) and the dipolar product ( 8a ) are obtained. Moreover, triisopropyl phosphite ( 2c ) reacts with 1b to give both the S‐alkyl and the N‐alkyl phosphonate adducts ( 9a,b ), respectively. Mechanisms are proposed to explain the formation of the new products, and their structures were confirmed on the basis of elemental analysis and spectral studies. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:594–601, 2001     

Synthesis and reactivity of 3-(trichlorogermyl)propanoic acid and 3-(triphenylgermyl) propanoic acid

3-(Trichlorogermyl)propanoic acid (la) reacts with phenylmagnesium bromide in malar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a).In the compounds la and 2a theβ-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide.The compound la reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give l,l-diphenyl-3-(triphenylgermyl)propanol (4a).The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also.Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy.Moreover,the compound la reacted with phenylmagnsium bromide in molar ratio 1:6,then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3-(triphenylgermyl)-1-propene (5a) in one pot reaction.Alkyl Ge-C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride ( LiAlH4) in good yiel     

Reactions of O-methyl o-quinone monoximes with methyl-, methylene- and methine- substituted aromatic compounds. Synthesis of benzo[d]oxazole and 1,4-benzoxazine derivatives

O-Methyl o-quinone monoxime 1 reacts thermally with compounds 2a-d or 6a,b or 7a,b to give mainly the corresponding 2-substituted phenanthroxazoles 3a-c and 8 . The reaction of 1 with aromatic methylene compounds lOa-c affords the ketones 13a-c in moderate to high yields. Similar products are also obtained from the reaction of monoximes 15a,b with some of the above reactants. The unexpected products 5 and 20 are obtained from the reaction of 1 with 2-methylimidazole ( 2d ) and with phenyloxirane ( 19 ) respectively, while the 4H-1,4-oxazine derivative 23 is obtained from the reaction of 1 with indene ( 21 ).