Chemistry of 1,2-diphospholide anions and 1,2-diphospholes

The main trends in the chemistry of 1,2-diphosphacyclopentadienes (1,2-diphospholes) and their derivatives 1,2-diphosphacyclopentadienide anions (1,2-diphospholide anions) were systematized, analyzed, and generalized. Methods for the generation of 1,2-diphospholide anions and their reactions with organic and organoelement electrophiles, as well as with transition metal complexes, were considered. Particular attention was paid to the cycloaddition reactions of 1-alkyl-1,2-diphospholes to obtain polycyclic chiral phosphines. A comparative analysis of the reactivity of 1,2-diphospholes and 1,2-diphospholide anions with respect to other representatives of phosphacyclopentadienes and phosphacyclopentadienide anions was carried out. The potential of application of 1,2-diphosphacyclopentadiene derivatives for the design of materials with magnetic, catalytic, and optical properties was shown.

     

Reactions of 1-alkyl-1,2-diphospholes with 1,3-dipoles: diphenyldiazomethane and nitrones

The reaction of 1-alkyl-1,2-diphosphacyclopenta-2,4-dienes (1-alkyl-1,2-diphospholes) (1) with diphenyldiazomethane proceeds at room temperature via unstable [3+2] cycloadducts to form bicyclic phosphiranes (2). However, 1-alkyl-1,2-diphospholes (1) react with N,alpha-diphenylnitrone or N-tert-butyl-alpha-phenylnitrone depending on the temperature to give either dimers of 1-alkyl-1-oxo-1,2-diphospholes (5) or 1-alkyl-1,7-dioxo-6-azo-1,7-diphospha-bicyclo[3.2.0]hept-2-enes (7) - phosphorus analogues of β-lactams.     

Efficient syntheses of novel indeno[1,2-b]chromenone derivatives via hetero-Diels-Alder reactions of 2-(arylmethylene)-1H-indene-1,3(2H)-diones with enaminones

Efficient syntheses of novel 10-aryl-5a-(arylamino)-9-hydroxy-5a,6,7,8-tetrahydroindeno[1,2-b]chromen-11(10H)-one derivatives has been reported by [4+2] cycloaddition reactions of electron-deficient 2-(arylmethylene)-1H-indene-1,3(2H)-dione heterodienes with electron-rich enaminones in [bmim]BF₄ at 80?°C and in acetic acid at 80?°C. Dimedone/cyclohexane-1,3-dione enaminones have been used as dienophiles in Inverse Electron Demand hetero-Diels-Alder reactions. The products were obtained in high yields by a simple work up.     

Reactions of 1,3,4-triphenyl-1,2-dihydrophosphete

In contrast to previously reported reactivity of the tungsten pentacarbonyl complex of a 2-substituted 1,2-dihydrophosphete, which apparently undergoes electrocyclic ring opening to the corresponding 1-phospha-1,3-butadiene and subsequent [4+2] cycloaddition reactions with dienophiles, the reaction chemistry of 1,3,4-triphenyl-1,2-dihydrophosphete is dominated by its nucleophilic nature. Although low to modest yields of cycloadducts are obtained with some dienophiles, the reactions forming these products are apparently stepwise, as indicated by the loss of stereochemistry in the reaction of dimethyl maleate and in the competitive formation of a phosphorus-free dimer in the reaction of N-methylmaleimide. Dimethyl acetylenedicarboxylate affords three major products, each of which incorporates two equivalents of the acetylene, again apparently a result of initial nucleophilic addition of the dihydrophosphete to the “dienophile.” © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:9–19, 1998     

Regio- and stereoselective 1,3-dipolar cycloaddition of arylnitrile oxides to 5-acetoxy-2(5H)-furanone

Summary Arylnitrile oxides undergo regio- and stereo-specific 1,3-dipolar cycloaddition reactions with 5-acetoxy-2(5H)-furanone. In each case a single product3a–3g results from ananti approach to the 5-acetoxy substituent, the oxygen of the 1,3-dipole being attached to C-4 of furan. Under similar conditions 5-benzoyloxy-2(5H)-furanone yields3h–3i. The structures of the adducts were determined by¹H- and¹³C-NMR spectroscopy.

---

Regio- und stereoselektive 1,3-dipolare Cycloaddition von Arylnitriloxiden mit 5-Acetoxy-2(5H)-furanon

Zusammenfassung Arylnitriloxide reagieren mit 5-Acetoxy-2(5H)-furanon in einer regio- und stereoselektiven 1,3-dipolaren Cycloaddition. In jedem der untersuchten Fälle ergaben sich die einheitlichen Produkte3a–3g als Folge eineranti-Annäherung an den 5-Acetoxysubstituenten, wobei der Sauerstoff des 1,3-Dipols an das C-4 des Furans addiert. Unter ähnlichen Bedingungen ergab 5-Benzoyloxy-2(5H)-furanon die Produkte3h–3i. Die Strukturen der Addukte wurden mittels¹H-und¹³C-NMR bestimmt.

     

First Synthesis of 2-Vinylindole and its diels-Alder Reactions with CC-Dienophiles

By means of an intramolecular Wittig process, 2-vinylindole ( 2 ) was prepared. The indole 2 functions as a heterocyclic, donor-activated 1,3-diene and undergoes [4+2] cycloaddition reactions with dimethyl acetylenedicarboxylate, N-phenylmaleimide, and p-benzoquinone leading to the novel carbazole dervatives 3 , 4 , 5c , 6 and 7 respectively. The reaction of 2 with acceptor (A)-Substituted dienophiles (e.g.) ACH?CH₂, AC≡(CH) does not yield products that can be isolated.     

Synthesis and Reactivity of 2-(1,2,3-Dithiazol-5- Ylidene)Aminothiophenes

The reaction of aminothiophenes (1) with Appel's salt (2) affords 2-(1,2,3-dithiazol-5-ylidene)aminothiophenes (3). Under the action of ZnCl₂, the latter compounds are transformed into 1,3-oxazin-4-one systems (4). The reactions of compounds 4 with dienophiles under atmospheric or high pressure give thienopyridines (6–11); the reactions with amines produce pyrimidinones (12) and guanidines (14–15).     

Fully regio- and endo-stereoselective synthesis of new polycyclic allylic sulfides via a Diels-Alder reaction. Synthetically useful transformations of these sulfides

Thermal and Lewis acid catalyzed cycloadditions of (Z)-1,2-diheterosubstituted-1,3-dienes to a variety of dienophiles are described. Both endo/exo and regioselectivity have been investigated. In all cases cycloaddition reactions exhibited full regio- and endo-stereoselectivity. The obtained cycloadducts are new polycyclic allylic sulfides carrying much structural and stereochemical informations. Work on transformation of the adducts, mainly to the corresponding new 1,3-dienes and aromatic compounds, is also presented.     

1,3-dipolar cycloadditions of arylnitrile oxides and 2-diazopropane with 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives

The reactions of arylnitrile oxides 2 and 2-diazopropane 5 with 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives 1 have been studied. 1,3-dipolar cycloaddition of arylnitrile oxides and 2-diazopropane with 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives is taking place regiospecifically. The asymmetric induction expected by the chiral centre of the 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives was very effective, diastereoisomers 3 and 4 were formed in an approximate 90:10 ratio. The stereoselectivity of the 1,3-dipolar cycloaddition of the 2-diazopropane with the 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives are investigated. The attack of the 1,3-dipole occurred from the less hindered face of the dipolarophile, giving the isomer 6.     

BNN-1,3-dipoles: isolation and intramolecular cycloaddition with unactivated arenes

The mono-base-stabilized 1,2-diboranylidenehydrazine derivatives featuring a 1,3-dipolar BNN skeleton are obtained by dehydrobromination of [ArB(Br)NH]₂ (Ar = 2,6-diphenylphenyl (Dpp), Ar = 2,6-bis(2,4,6-trimethylphenyl)phenyl (Dmp) or Ar = 2,4,6-tri-tert-butylphenyl (Mes*)) with N-heterocyclic carbenes (NHCs). Depending on the Ar substituents, such species can be isolated as a crystalline solid (Ar = Mes*) or generated as reactive intermediates undergoing spontaneous intramolecular aminoboration of the proximal arene rings via [3 + 2] cycloaddition (Ar = Dpp or Dmp). The latter reactions showcase the 1,3-dipolar reactivity toward unactivated arenes at ambient temperature. In addition, double cycloaddition of the isolable BNN species with two CO₂ molecules affords a bicyclic species consisting of two fused five-membered BN₂CO rings. The electronic structures of these BNN species and the mechanisms of these cascade reactions are interrogated through density functional theory (DFT) calculations.

The mono-base-coordinated 1,2-diboranylidenehydrazine derivatives exhibiting the BNN-1,3-dipolar reactivity toward unactivated arenes and CO₂ are reported.     

Efficient method for the synthesis of 1,2,3-triazole functionalized isoxazolidine derivatives by 1,3-dipolar cycloaddition of nitrones with terminal olefins

1-Phenyl-1,2,3-triazole-4-carbaldehyde 1 was treated with different N-alkyl hydroxylamine hydrochlorides 2 using NaHCO₃ to obtain 1,2,3-triazole substituted N-alkyl nitrones 3a–c. The nitrones 3a–c were further reacted with different substituted olefins and furnished 2-alkyl-3-(1-phenyl-1H-1,2,3-triazol-4-yl)-5-(substituted)isoxazolidine derivatives 4a–p in high yields via 1,3-dipolar cycloaddition reaction.     

Recyclization of ethyl 1-alkyl-5-benzoyl-6-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carboxylates into Bicyclic <Emphasis Type="Italic">N</Emphasis>-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxamide derivatives by the action of nitrogen-containing 1,4- and 1,5-binucleophiles

Reactions of ethyl 1-alkyl-5-benzoyl-6-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carboxylates with nitrogen-containing 1,4- and 1,5-binucleophiles (o-phenylenediamine, o-aminobenzenethiol, ethane-1,2-diamine, and propane-1,3-diamine) involved recyclization, leading to the formation of fused N-alkyl-5-benzoyl- 2-oxo-1,2-dihydropyridine-3-carboxamides, diethyl 6,6′-oxybis(1-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxylates), and diethyl 6,6′-[ethane-1,2-diyl(or propane-1,3-diyl)diimino]bis(1-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxylates), depending on the reactant ratio. The sequence of formation of intermediate recyclization products was determined.     

Quinolone analogues 7 [1‐6]. Synthesis of 3‐Heteroaryl‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones

The 3‐heteroaryl‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones 6a‐e were synthesized by the oxidative‐hydrolytic ring transformation of the 3‐heteroaryl‐1,2‐diazepino[3,4‐b]]quinoxaline‐5‐carbonitriles 9a‐c , which were obtained by the 1,3‐dipolar cycloaddition reaction of the 2‐(2‐heteroarylmethylene‐1‐methylhydrazino)quinoxaline 4‐oxides with 2‐chloroacrylonitrile. The assignment of the thiophene and furan ring protons was carried out through the data of the NOE, decoupling, and coupling constants.     

Structure Determination of an Unusual [2.2]paracyclophane Derivative by NMR Spectroscopy

Our ongoing study on cycloaddition reactions of dienes with different dienophiles afforded a great variety of derivatives with interesting molecular structures and electronic behavior. A new type of angularly annelated [2.2]paracyclophane (3) has been synthesize by the Diels–Alder reaction of 4-(2-propenyl[2.2]paracyclophane (1) and 1,4-benzoquinone (2) under high pressure conditions. The structure determination of this compound has been achieved by NMR measurements and semiempirical calculations.     

Reactions of cyclic 1,3-dicarbonyl compounds with 1,2(1,4)-dihydro-1-methyl-2(4)-methylene-N-heterocycles. A new access to 6,12-methano-dibenz[d,g]-[1,3]oxazocinones

Summary The enamine-type methylene-N-heterocycles1–5 react with cyclic 2-ethoxymethylene-1,3-dicarbonyl compounds6 to give 2-[2-(hetarylidene)ethylidene]-1,3-dicarbonyl compounds7–14. The result of the reactions between 1,2-dihydro-1-methyl-2-methylene-quinoline (1a) and cyclic 1,3-dicarbonyl compounds depends on the nature of the dihydro intermediatesA/B. Dehydrogenation of keton intermediatesA results in 2-(1,2-dimethyl-4(1H)-quinolylidene)-1,3-dicarbonyl compounds17–21. Enol intermediatesB with 6-membered dicarbonyl ring form 6,12-methano-dibenz-[d,g][1,3]oxazocinones22–25.¹H NMR spectra and X-ray structure analysis prove the structure of23.

---

Reaktionen cyclischer 1,3-Dicarbonylverbindungen mit 1,2(1,4)-Dihydro-1-methyl-2(4)-methylen-N-heterocyclen. Ein neuer Zugang zu 6,12-Methano- dibenz[d,g][1,3]oxazocinonen

Zusammenfassung Aufgrund ihres Enamincharakters reagieren die Methylen-N-heterocyclen1–5 mit cyclischen 2-Ethoxymethylen-1,3-dicarbonylverbindungen6 zu den 2-[2-(Hetaryliden)ethyliden]-1,3-dicarbonylverbindungen7–14. Das Ergebnis der Reaktionen zwischen 1,2-Dihydro-1-methyl-2-methylen-chinolin (1a) und cyclischen 1,3-Dicarbonylverbindungen hängt von der Natur der zwischenzeitlich entstehenden DihydroverbindungenA/B ab. Die Intermediat-KetoneA gehen durch Dehydrierung während der Reaktion in die 2-(1,2-Dimethyl-4(1H)chinolyliden)-1,3-dicarbonylverbindungen17–21 über. Die Intermediat-EnoleB mit sechsgliedrigem Dicarbonylring bilden in intramolekularer Reaktion die 6,12-Methano-dibenz[d,g][1,3]oxazocinone22–25, deren Struktur am Beispiel der Verbindung23 durch¹H-NMR sowie durch Röntgenkristallstrukturanalyse bewiesen wird.

     

Glycoside Synthesis with Anomeric 1-N-Glycobiosyl-1,2,3-triazoles1

Abstract

1,3-Dipolar cycloaddition of the acetylated 1,2-trans- and 1,2-cis-cellobiosyl, -lactosyl, -maltosyl, and -melibiosyl azides with various acetylenedicarboxylic acid esters gave the corresponding 1-N-glycobiosyl-1,2,3-triazoles (1a,b,c-8a,b,c) which have been used as glycosyl donors for the synthesis of oligosaccharides (15-17) and an anthracycline type antibiotic (18).     

Zur Umsetzung des 3,4,5,6-Tetrahydro-6-hydroxy-4,4,6-trimethyl-1,3-thiazin-2-thions mit primären Aminen

Tetrahydro-6-hydroxy-4,4,6-trimethyl-1,3-thiazine-2-thione (1 a) reacts with methyl-, ethyl- and n-butylamine to the corresponding 1-alkyl-6-alkylaminotetrahydro-2(1H)-pyrimidinethione12 but withi-propylamine to tetrahydro-6-isopropylamino-1,3-thiazine-2-thione (6 d). On treatment withDCC,6 d is rearranged to dihydro-4-isopropylamino-2(1H)-pyridinethione (8 d), and 6-amino-tetrahydro-1,3-thiazinethione (6 a) to dihydro-4,4,6-trimethyl-2(1H)-pyrimidinethione (10 a). The reaction of 6-aminothiazinethiones6 a, d and 6-(4-morpholinyl)-thiazinethione13 resp., with methylamine leads to 1-methyl-6-methylamino-pyridinethione12 b. 1-Alkyl-6-alkylamino-tetrahydro-2(1H)-pyrimidinethiones (12) react at reflux temperature to dihydro-1-alkylpyrimidinethiones10. With methylamine only 6-methylamino-3,4,4,6-tetramethyl-1,3-thiazine-2-thione (6 f) is formed from tetrahydro-6-hydroxy-tetramethyl-1,3-thiazine-2-thione (1 b).     

Synthesis of 3-Acyl-1,2-benzisoxazoles

A convenient method for the synthesis of 3-acyl-1,2-benzisoxazoles, which are unstable toward bases, is described. Base-catalyzed cyclization of 2-alkyl- and aryl-1,3-dithian-2-yl o-chlorophenylketoximes 4a-1 gave 3-(2-alkyl- and aryl-1,3-dithian-2-yl)-1,2-benzisoxazoles 8a-1 , which were converted into the corresponding 3-acyl-1,2-benzisoxazoles 1a-1.     

Reactions of diazoalkanes with unsaturated compounds. 14. Reactions of diazomethane,diazocyclopropane, and methyl diazoacetate with 1,1,2,2-tetrafluoro-3-vinylcyclobutane and 2,3,3-trifluoro-1-vinylcyclobutene to form [3+2] and [1+2] cycloadducts

The reactions of diazomethane and diazocyclopropane generated in situ with 1,1,2,2-tetrafluoro-3-vinylcyclobutane (1) and 2,3,3-trifluoro-1-vinylcyclobutene (2) proceeded at the double bond of the substituent as the 1,3-dipolar cycloaddition to form the corresponding 1-pyrazolines. Under the conditions of thermolysis (340—400 °C), the resulting cyclobutylpyrazolines 4 and 5 selectively lost the dinitrogen molecule to generate 3-cyclopropyl-1,1,2,2-tetrafluorocyclobutane (6) or 1,1,2,2-tetrafluoro-3-spiropentylcyclobutane (7), respectively, in high yields. In the presence of Pd(acac)₂, the reactions of these fluorine-containing unsaturated compounds and 2-chloro-1,1,2-trifluoro-3-vinylcyclobutane (3) with diazomethane gave rise directly to cyclopropane derivatives 6, 11, and 12, respectively. The reactions of compounds 1 and 2 with methyl diazoacetate in the presence of Rh₂(OAc)₄ proceeded analogously to yield cis- and trans-disubstituted cyclopropanes.     

1,3-Dipolare Cycloadditionen von Nitrilium-Betainen mit 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thion

1,3-Dipolar cycloadditions of Nitrilium Betaines with 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione Benzonitrile ylides, imines, and oxides undergo smooth 1,3-dipolar cycloaddition reactions with the exocyclic, C,S-double bond of 4,4-dimethyl-2-phenyl-2-thiazolin-5-thione ( 1 ), yielding heterocyclic spiro-compounds. The structure of the cycloadducts 5c, 5c ′, and 3f (Fig.) have been established by x-ray structure analysis. With the benzonitrile ylides, the two regioisomeric cycloaddition modes have been observed, depending on the substituents of the ylide-C-atom. It is questionable, whether the reaction of 1 and the oxazaphosphol 8 (Schemes 8 and 13) proceeds via the corresponding nitrile ylide as an intermediate.