OLEFIN SYNTHESIS USING LITHIUM DERIVATIVES OF N,N,N',N'-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS

Abstract

The reaction of lithium derivatives of N,N,N',N'-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with aldehydes 2 is studied. It is found that under certain reaction conditions (THF, 5 hrs at -70°C and then allowing to warm to room temperature) the aldol stage of the reaction is highly stereoselective, only erythro adducts (2-hydroxyphosphonamides) 3, 4 being formed in 47–75% yields. By heating of 3 and 4 in neutral medium the corresponding (Z)-olefins 5, 6 are obtained (yields 64–74%). It is established that an acid catalyzed olefination of 2-hydroxyphosphonamides is also possible, but the reaction is not stereospecific.     

OLEFIN SYNTHESIS VIA THE LITHIUM DERIVATIVE OF THE N,N,N′,N′-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS. 3 SYNTHESIS OF SOME β-DISUBSTITUTED STYRENES

Abstract

The reaction of Li-derivatives of N,N,N′,N′-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with alkanones, cycloalkanones, alkylaryl-and diarylketones 2a-h is studied. It is found that in THF at-70°C adducts 3-Li and 4-Li are formed, the corresponding hydroxyl compounds 3 and 4 being isolated in 36–81% yields, while by elevated temperatures the reaction is completely shifted to the starting 1-Li and 2. By thermolysis of 3 and 4 in neutral medium olefins 5 and 6 are obtained even from readily enolysable ketones. The stereochemistry of the addition reaction with nonsymmetrical ketones as well as the influence of the substituents at the carbonyl groups on the conformation and adsorption properties of the adducts are discussed.     

OLEFIN SYNTHESIS VIA THE LITHIUM DERIVATIVES OF THE N,N,N,N′-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS. 2. SYNTHESIS OF SOME (Z)-ORTHO-AND PARA-SUBSTITUTED STILBENES

Abstract

The reaction of the lithium derivatives of N,N,N′,N′-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with ortho- and para-substituted benzaldehydes 2 is studied. Reaction conditions are found for erythro-stereoselective addition of 1 to 2 with high diastereomeric purity (95–99%) of the erythro adducts 3, 4 (yields 35–72%). By thermolysis of the adducts in neutral medium the corresponding (Z)-ortho and para-substituted stilbenes 5, 6 are obtained. Some factors causing the predominant formation of the erythro adducts 3, 4, as well as the influence of the ortho-substituents on the equilibrium threo-3, 4 ? erythro-3, 4 are discussed.     

An Efficient Approach to 2-CF3-Indoles Based on ortho-Nitrobenzaldehydes

The catalytic olefination reaction of 2-nitrobenzaldehydes with CF₃CCl₃ afforded stereoselectively trifluoromethylated ortho-nitrostyrenes in up to 88% yield. The reaction of these alkenes with pyrrolidine permits preparation of α-CF₃-β-(2-nitroaryl) enamines. Subsequent one pot reduction of nitro-group by Fe-AcOH-H₂O system initiated intramolecular cyclization to afford 2-CF₃-indoles. Target products can be prepared in up to 85% yields. Broad synthetic scope of the reaction was shown as well as some followed up transformations of 2- CF₃-indole.     

Unusual ring opening of a Cyclopropylideneamine derivative during a favorskii-type rearrangement of α-Chloroketimines

The reaction of N-(3-chloro-3-methyl-2-butylidene)amines (i.e. α-chloroketimines) with lithium diisopropylamide in tetrahydrofuran gave rise to an unexpected reaction leading to 2-(N-alkylimino)-3,3-dimethyl-1-isopropyl-5-(2-methylpropylidene) pyrrolidines in good yields. The reaction mechanism is interpreted in terms of a Favorskii-type 1,3-dehydrochlorination affording intermediate cyclopropylideneamines (N-analogues of cyclopropanones), which “dimerize” in an unusual way. This mechanism entails a “normal” opening as well as an “abnormal” opening of incipient cyclopropylideneamine adducts. This rearrangement represents an example of the scarcely reported abnormal opening of functionalized cyclopropylamines.     

Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

Summary: “True” initial polymerization rates can be calculated from the adiabatic temperature rise under isoperibolic conditions. They are much higher than initial polymerization rates measured by standard mass flow meter methods under quasi‐steady‐state conditions. These high initial rates are followed by a fast apparent deactivation (“attenuation”) until a constant (“plateau”) activity is reached at low polymerization yields of 2–3 g PP · (g catalyst)⁻¹ caused by an “increasing degree of encapsulation” of active sites. Mass transfer limitations are not observed. Cross sectional SEM images of the polymer samples support these kinetic findings.

Rate of polymerization (g of PP · (g catalyst)⁻¹ · h⁻¹) and yield of polymerization (g of PP · (g catalyst)⁻¹) as function of time.     

A PETERSON OLEFINATION REACTION USING SILYL-SUBSTITUTED SULFONAMIDE CARBANIONS. SYNTHESIS OF VINYLIC SULFONAMIDES

Abstract

α-Trimethylsilyl-substituted sulfonamides RCH(SiMe₃)SO₂N(CH₃)₂ (3), (R[dbnd]H, CH₃ and C₆H₅) are synthetized in almost quantitative yields. Their lithium derivatives 4 undergo a smooth Peterson olefination reaction with nonenolisable carbonyl compounds to give good to excellent yields of vinylsulfonamides 6. With R[dbnd]H, the reaction is highly E-stereoselective. Moderate stereoselectivity is obtained in the cases of R[dbnd]CH₃ and R[dbnd]C₆H₅.     

Amide-silyl ligand exchanges and equilibria among group 4 amide and silyl complexes

M(NMe2)4 (M = Zr, 1a; Hf, 1b) and the silyl anion (SiButPh2)- (2) in Li(THF)2SiButPh2 (2-Li) were found to undergo a ligand exchange to give [M(NMe2)3(SiButPh2)2]- (M = Zr, 3a; Hf, 3b) and [M(NMe2)5]- (M = Zr, 4a; Hf, 4b) in THF. The reaction is reversible, leading to equilibria: 2 1a (or 1b) + 2 2 <--> 3a (or 3b) + 4a (or 4b). In toluene, the reaction of 1a with 2 yields [(Me2N)3Zr(SiButPh2)2]-[Zr(NMe2)5Li2(THF)4]+ (5) as an ionic pair. The silyl anion 2 selectively attacks the -N(SiMe3)2 ligand in (Me2N)3Zr-N(SiMe3)2 (6a) to give 3a and [N(SiMe3)2]- (7) in reversible reaction: 6a + 2 2 <--> 3a + 7. The following equilibria have also been observed and studied: 2M(NMe2)4 (1a; 1b) + [Si(SiMe3)3]- (8) <--> (Me2N)3M-Si(SiMe3)3 (M = Zr, 9a; Hf, 9b) + [M(NMe2)5]- (M = Zr, 4a; Hf, 4b); 6a (or 6b) + 8 <--> 9a (or 9b) + [N(SiMe3)2]- (7). The current study represents rare, direct observations of reversible amide-silyl exchanges and their equilibria. Crystal structures of 5, (Me2N)3Hf-Si(SiMe3)3 (9b), and [Hf(NMe2)4]2 (dimer of 1b), as well as the preparation of (Me2N)3M-N(SiMe3)2 (6a; 6b) are also reported.     

Mechanism of Formation of Aromatic Vinylphosphonium Salts via the Peterson Olefination

The mechanism of the reaction of tributyl[(trimethylsilyl)methylene]phosphorane with benzaldehyde and its p‐substituted analogues has been examined. It has been found that the electronic nature of the p‐substituents in aromatic aldehydes strongly influences the stereochemical and kinetic outcome of the Peterson olefination whereas temperature substantially affects their Hammett correlation. This indicates that the Peterson olefination is a multistep reaction involving the formation of at least an oxyanion/betaine and a carbanion as intermediates. In turn, moderate Z‐selectivity might be the result of “steric approach intermediate control”; however, E‐selectivity seems to result from the silicon–oxygen interaction and interactions of steric substituents in competing erythro‐ and threo‐betaines.     

An Efficient Procedure for the Preparation of 3′-Acetyl-2′,3′-dihydrobenzothiazoles by Ring Contraction of 2′,3′-Dihydro-1,5-Benzothiazepines Under Acetylating Conditions

Reaction of 2-benzoyl-6-hydroxy-3-methyl-5-(2′-substituted-2′,3′-dihydro-1,5-benzothiazein-4′-yl) benzofurans (4a-f) with a mixture of acetic anhydride and pyridine afforded 6-acetoxy-2-benzoyl-3-methyl-5-(3′-acetyl-2′-substitutedstyryl-2′,3′-dihydrobenzothiazole-2′-yl) benzofurans (5a-f) as sole products in good yields. A reaction mechanism for the ring contraction is proposed. All the compounds (5a-f) were screened for their antifeedant activity by the “Non-Choice test method” using 6 h prestarved fourth instar larvae of Spodoptera litura F. Compounds 5a, 5c and 5d exhibited highest antifeedant activity.     

Synthesis of Some Novel Glucosyl Triazoles from 2,3,4,6-Tetra-O-pivaloyl-D-glucopyranosyl Azide

In the present study, we have synthesized a series of novel glucosyl triazoles for the first time. The glucosyl triazoles 4a–e were synthesized by reaction of some azidoglycosides with various terminal alkynes via a copper-catalyzed [3+2] cycloaddition (“click chemistry”) and were deprotected to afford the corresponding glucosyl triazoles 5a–e in good yields. The structures of the new compounds were determined by IR, NMR spectroscopy, and mass spectrometry. The antitumor (human cervical cancer cell) activity was evaluated for the target compounds.     

A new intramolecular recyclization in water‐base cleavage reaction of 2,2‐dialkyl‐4‐hydroxymethylbenz[f]iso indolinium bromides and chlorides

The water‐base cleavage reaction of 2,2‐dialkyl‐4‐hydroxymethylbenz[f]isoindolinium bromides and chlorides (2b‐g) and (4a‐g) was investigated. It was established that the above‐mentioned salts in water‐base cleavage reaction undergo intramolecular recyclization. As a result 1,3‐dihydro‐4‐dialkylaminomethyl‐naphto[1,2‐c]furans (5a‐g) are obtained in 62‐72% yields. The same products in 65‐70% yields may be obtained by step cyclization cleavage reaction of dialkyl‐4‐hydroxybutyn‐2‐yl‐(3‐phenylpropargyl) ammonium salts (1b‐g) and (3a‐g) , as well. The structure of the resulting amines 5a‐g are determined and approved by X‐ray diffraction, nmr and ir spectroscopic methods.     

Zur Reaktionsweise von Enaminen mit Cyclopropenonen IV. Einsatz von Ketenacetalen

A new interpretation – based on a reevaluation of the spectroscopic properties of products 16 to 27 – is proposed for the reaction of diphenyl-cyclopropen-one 14 and -thione 15 with ketene-A, N-diacetals 8 to 13 (A ? R₂N, RO and RS) originally reported by Sauer & Krapf. It is concluded that the previous structural assignments (see the a-structures), made on the assumption of a prevailing “C,C-insertion” reaction, must be rcplaced as follows: (1) All the “secondary adducts” are, in fact, derivatives (amides and lactams) of 2,3-diphenyl-penta-2, 4-dienoic acid and thioacid (structures 16b to 24b ); (2) the “isomerization products”, differ from the latter only in the configuration of the α,β-double bond (structures 25b and 26b ); (3) the common “hydrolysisproduct” is α,β-diphenyl-γ-methyl-γ-hydroxy-Δ^α-butenolide ( 27b ), The above cyclopropenone-ketcneacetal reactions represent, therefore, cases of “C, N-insertion”. This is rationalized with a reaction scheme, in which the “acylide” structure of the “primary adducts” plays a role.     

Reaction of malonates with camphoranile synthesis of 4‐hydroxy‐2‐pyridones attached to the bornane ring system

The reaction of camphoraniles 3a,b with “magic malonates” (bis‐2,4,6‐trichlorophenylmalonates) 4a,b leads to 4‐hydroxy‐2(1H)‐pyridones attached to bornane ring system 6a‐c in good yields. Less satisfactory yields were obtained with the diethyl malonate 5b . The reaction of an excess of diethyl malonate 5 itself with 3b yields the pyrono derivative 7 , which can readily be degraded via the acetyl derivative 8 to the basic structure 9 .     

Three component one-pot synthesis of novel pyrimidino thiazolidin-4-ones catalyzed by activated fly ash

Abstract

2-Phenyl-3-(4,6-diarylpyrimidin-2-yl) thiazolidin-4-ones, 12–22, were synthesized with good yields in a short reaction time by the “one-pot” multicomponent reaction of the appropriate 2-amino-4,6-diarylpyrimidines, benzaldehyde, and thioglycolic acid under microwave irradiation in the presence of activated fly ash catalyst. The characterization of these compounds was confirmed by melting point, elemental analysis, MS, FT-IR, and one-dimensional NMR (¹H and ¹³C) spectroscopic data.     

STEREOSELECTIVITY OF THE WITTIG-HORNER REACTION WITH BENZYLPHOSPHONATE CARBANIONS AND ALDEHYDES

Abstract

The interaction of Li-diethylbenzylphosphonate 1-Li with aldehydes 2 is studied at different reaction conditions, the corresponding β-hydroxyethanephosphonate 3 being isolated. It is found that in these cases the aldol stage of the HWE reaction is not stereoselective or threo isomers predominate. The elimination stage leads only to trans-alkene due to the electron and steric influence of the substituents at the phosphorus atom.     

3,5-bis(trifluoromethyl)phenyl sulfones in the direct Julia-Kocienski olefination

3,5-bis(trifluoromethyl)phenyl (BTFP) sulfones 7 have been employed in the Julia-Kocienski olefination reaction with carbonyl compounds. Sulfones 7 are readily prepared in high yields (64-97%) from commercially available 3,5-bis(trifluoromethyl)thiophenol through an alkylation/oxidation two-step sequence. The stability of metalated BTFP sulfones has been studied and compared with heteroaryl benzothiazol-2-yl (BT), 1-phenyl-1H-tetrazol-5-yl (PT), and 1-tert-butyl-1H-tetrazol-5-yl (TBT) sulfones 9-11 under different reaction conditions. The Julia-Kocienski olefination between alkyl BTFP sulfones 7 and a wide variety of aldehydes affords the corresponding 1,2-disubstituted alkenes and dienes in good yields and stereoselectivities. This one-pot protocol can be performed using KOH at room temperature or the phosphazene bases P2-Et and P4-t-Bu at -78 degrees C or rt and has been successfully used in a high-yielding and stereoselective synthesis of various methoxylated stilbenes such as trimethylated resveratrol. These new reaction conditions for the Julia-Kocienski olefination reaction have been also studied with BT, PT, and TBT sulfones, giving poorer results. Methylenation of aliphatic and aromatic aldehydes, ketones, and 1,2-dicarbonyl compounds is carried out through the modified Julia olefination using BTFP methyl sulfone 7d to give terminal alkenes and dienes. Mechanistic studies of the olefination reaction between benzyl BTFP sulfone 7a and aromatic aldehydes performed by KOH-induced Smiles rearrangement of stereodefined syn- and anti-beta-hydroxyalkyl BTFP sulfones indicate that the stereocontrol of the reaction is determined in the elimination step.     

Fast Gas Chromatographic Assessment of Polychlorobiphenyl Levels in Wall Plaster Coats

Abstract

Sampling (“scrape test”) and analytical procedures were defined to determine PCBs in sorbing solid surfaces such as wall plaster. After sampling, samples were extracted by means of a mechanical device. Following steps included clean-up on a multilayer chromatographic column and assessment with macrobore capillary gas chromatography equipped with an electron capture detector. Mean recovery yields were ≧75% for PCB levels from 2.00 to 7000μg/m² (0.550–1940 μg/kg). Intralaboratory tests performed by two independent operators yielded: (a) maximum deviation from expected value, 25%; (b) maximum deviation between operators, 17%; and (c) maximum variation coefficient, 20%. Background PCB levels in wall surface layer samples were ≧2.9μg/m² (≧0.81 μg/kg). The analytical procedure tested with agricultural topsoil samples provided mean recovery yields >65% for PCB levels ≧500 μg/ kg (≧ 50 mg/m²).     

Effect of Microwave Irradiation on Reaction of Arylaldehyde Derivatives with Some Active Methylene Compounds in Aqueous Media

Abstract

The effect of microwave irradiation on the condensation reactions of arylaldehydes 1 and active methylene compounds 2 in aqueous media was studied and compared with “classical” conditions. The results show that the condensation was carried out only under microwave irradiation in the presence of ammonium chloride as a catalyst, followed by dehydration, to afford (E)‐olefins 3. The protocol was used to synthesize coumarins by a condensation reaction of salicylaldehyde or its derivatives with various derivatives of ethylacetate 5 (e.g., R³CH₂CO₂Et; R³: CO₂Et, CO₂Me, COMe, CN) in high yields. These investigations will contribute to the development of environmentally friendly and inexpensive processes in organic synthesis.     

An Efficient Approach to the Synthesis of Ethyl α-Cyanoalkyl β-Substituted Acrylates by the HWE Olefination of Ethyl 2-(Diethoxyphosphoryl) Cyanoalkanoates

Ethyl α-cyanoalkyl β-substituted acrylates 5a–i were prepared in good yields on a synthetic scale by Horner–Wadsworth–Emmons olefination of the corresponding ethyl 2-(diethoxy-phosphoryl) cyanoalkanoates 3a–c using different aldehydes and anhydrous potassium carbonate in dry THF at reflux.