A new efficient and selective synthesis of ketones from alkanes or cycloalkanes, CO, and silanes in the presences of aprotic superacids

A new approach to the direct synthesis of ketones from alkanes or cycloalkanes (RH), CO, and silanes is proposed. Ketones were obtained in 50–97% yields from propane, butane, cyclopentane, cyclohexane, and methylcyclopentane on treatment with CO and silanes (Me₄Si, Et₄Si, orm- andp-XC₆H₄SiMe₃, where X=Cl, Me, OMe) in the presence of CX₄·2AlBr₃ (X=Br, Cl) superacids at 0°C. The reactions withm- andp-XC₆H₄SiMe₃ (X=Cl, Me) occur regioselectively to givem-ketones fromm-silanes andp-ketones fromp-silanes. However, the only product,p-MeOC₆H₄COR, is formed both fromm- andp-MeOC₆H₄SiMe₃. The reaction ofcyclo-C₅H₉CO⁺ with BzSiMe₃ results in an organosilicon ketone, Me₃SiCH₂C₆H₄COC₅H₉, while in the presence of an excess of an acylating system (after alcoholysis), Me₂Si(OR′)CH₂C₆H₄COR is formed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 947–952, May, 1998.     

An efficient and convenient method for the preparation of disulfides from thiols using oxygen as oxidant catalyzed by tert-butyl nitrite

An efficient and convenient tert-butyl nitrite-catalyzed selective aerobic oxidation of thiols has been developed. Under the optimal reaction conditions, a number of thiol derivatives including aromatic thiols, heteroaromatic thiols and aliphatic thiols can be converted into their corresponding disulfides in good to excellent yields.     

A new strategy of the chemical route to the cyclopropane structure: direct transformation of benzylidenemalononitriles and malononitrile into 1,1,2,2-tetracyanocyclopropanes

The new reaction was found: the direct formation of cyclopropanes from activated olefins and C-H acids. The action of free halogen or active halogen containing compounds on the equal amounts of benzylidenemalononitriles and malononitrile in basic alcohol solutions results in the formation of 3-aryl-1,1,2,2-tetracyanocyclopropanes in 65-95% yields. Thus, the new simple and efficient way to 3-aryl substituted tetracyanocyclopropanes was found directly from such simple and reasonable starting compounds as benzylidenemalononitriles and malononitrile.     

A stereocontrolled, efficient synthetic route to bioactive sphingolipids: synthesis of phytosphingosine and phytoceramides from unsaturated ester precursors via cyclic sulfate intermediates

An efficient and highly enantioselective method for the preparation of D-ribo- and L-lyxo-phytosphingosines (1a,b, respectively) and phytoceramides (2a,b) has been developed. The key steps in the syntheses are as follows: (i) osmium-catalyzed asymmetric dihydroxylation of 4-O-protected (E)-alpha,beta-unsaturated ester 5 (generated by dihydroxylation of 1-hexadecene, followed by oxidation to the aldehyde and Horner-Wadsworth-Emmons olefination), (ii) conversion to cyclic sulfate intermediate 7, and (iii) regioselective alpha-azidation of 7. Reduction of 4-O-protected 2-azido ester 8 via alpha-azidolactone 9 afforded phytosphingosine 1a. Staudinger reduction of the azido group of 8, followed by in situ N-acylation in aqueous media and reduction of the ester functionality with NaBH(4)/LiBr, provided phytoceramide 2a. By using a similar approach, phytosphingosine 1b was synthesized. D-erythro-4, 5-Dihydrosphingosine 1c and D-erythro-4,5-dihydroceramide 2c were synthesized in high yield from 1-hexadecanol via cyclic sulfate intermediate 15. The desired configurations at C-2, C-3, and C-4 of the sphingoid chain can be accessed readily by the route described here.     

A new route to acrylate oils: Crosslinking and properties of acrylate triglycerides from high oleic sunflower oil

Triglycerides with acrylate functionality were prepared from a new route that involves the singlet oxygen photooxygenation of high oleic sunflower oil and further reduction of the resulting hydroperoxide derivatives to a mixture of secondary allylic alcohols. These unsaturated alcohols can be further reduced to saturated alcohols. These two new hydroxyl‐containing triglycerides were functionalized as acrylate esters and radically crosslinked in presence of different amounts of pentaerythritol tetraacrylate. The crosslinking reactions were followed by FTIR spectroscopy and the thermal properties of the final materials were evaluated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1159–1167, 2009     

Formal synthesis of schulzeines B and C: A new route to Gurjar's lactams

Described is a formal synthesis of racemic schulzeines B and C that intercepts intermediates developed by Gurjar and co-workers. The synthetic sequence features an annulative coupling of a ketimine and acrylic acid enabling the construction of the benzoquinolizidine nucleus in a highly convergent manner. We also examined a continuous-flow version of the thermal aza-annulation, which proved less practical as compared to the batch processes.     

SXI route to mesostructured materials from Fau and Beta zeolite precursors: A comparative study of their assembly behaviors in extremely acidic media

Mesoporous molecular sieves were synthesized from Beta and Fau zeolite precursors through S⁺X⁻I⁺ route under extremely acidic conditions in parallel (designated as M_Beta and M_Fau, respectively). The textural properties of M_Fau were different from its M_Beta counterpart but resembled normal MCM-41 silica from TEOS. Al content in M_Beta was almost equivalent to that in the initial Beta zeolite precursors, whereas only trace Al species was present in M_Fau from elemental analysis results. The hydrothermal stability of M_Beta after post-synthesis ammonia treatment was considerably improved compared with normal MCM-41 aluminosilicates, whereas the M_Fau after the same procedure was as unstable as normal MCM-41 silica. Thus, the assembly behaviors of Beta and Fau zeolite precursors were comparatively studied based on these results. The microstructure of Fau zeolite precursors were degraded by the extremely acidic condition, and Al species was dissolved into the synthesis mixture. However, Beta zeolite precursors survived the chemical attack of extremely acidic media and were incorporated into mesostructured framework as primary building units.     

A direct synthesis of nitriles and amides from aldehydes using dry or wet alumina in solvent free conditions

An efficient and simple procedure for the direct conversion of aldehydes into the corresponding nitriles with NH₂OH·HCl/dry Al₂O₃/MeSO₂Cl or amides with NH₂OH·HCl/wet Al₂O₃/MeSO₂Cl are studied.     

A new route to 1-phenylnaphthalenes by cycloaddition: a simple and selective synthesis of some naphthalene lignan lactones

2-(2-Dithianyl)benzhydrols ($\text{2}$ a-c) undergo facile cycloaddition reaction with maleic anhydride under thermal conditions to give 1-phenyl-naphthalenes ($\text{7}$ a-c) in one step. The naphthalenes ($\text{7}$ a-c) have been converted into the naphthalene lignan lactones, ($\text{9}$ a-c) and ($\text{10}$ a-c).     

A convenient synthetic route to furan esters and lactones by palladium-catalyzed carboalkoxylation or cyclocarbonylation of hydroxyl-substituted 3-iodofurans

An effective palladium-catalyzed protocol for the intermolecular carboalkoxylation or intramolecular cyclocarbonylation of hydroxyl-substituted 3-iodofurans under carbon monoxide pressure has been developed. The 3-iodofurans are readily prepared by iodocyclization of 2-(1-alkynyl)-2-alken-1-ones in the presence of various diols.     

A "green" route to perylene dyes: direct coupling reactions of 1,8-naphthalimide and related compounds under mild conditions using a "new" base complex reagent, t-BuOK/DBN.

The direct coupling reactions of 1,8-naphthalimide compounds efficiently occurred at 130 or 170 degrees C without the intervention of the leuco form dyes in the presence of base complex reagent, t-BuOK/1,5-diazabicyclo[4.3.0]non-5-ene (DBN), to give the corresponding perylene dyes in good yields with > 95% purities. A possible mechanistic speculation for these oxidative coupling reactions is briefly discussed.     

Formation of novel molybdenum and tungsten sulfides by reduction of MoS2 and WS2: A new route to chevrel phases

Pt-catalyzed hydrogen reduction of MoS₂ and WS₂ at 1000–1050°C yields new metal-rich sulfidesM₂₁S₈ andM₁₄S₅ (M =Mo or W). The reduction of MoS₂ proceeds via the intermediate Mo₆S₈. Chevrel phases, Cu_xMo₆S₈(x < 4.0) and Ni₂Mo₆S₈, are readily prepared by hydrogen reduction of MoS₂ in the presence of the ternary metal.     

Cross-coupling of E,E-1,4-diiodobuta-1,3-diene with nucleophiles catalyzed by Pd or Ni complexes: a new route to functionalized dienes

E,E-1,4-Diiodobuta-1,3-diene can enter into cross-coupling reactions with carbon- or other element-centered nucleophiles in the presence of Pd or Ni complexes as catalysts. Convenient procedures were developed for the stereoselective synthesis of E,E-1,4-dialkenylbuta-1,3-dienes, dienyl-1,4-bisphosphonates, E,E-1,4-bis(diphenylphosphino)buta-1,3-diene, E,E-1,4-diphenylbuta-1,3-diene, and E,E-1,4-bis(thiophenyl)buta-1,3-diene.     

A sequence of electrophile induced cyclisation and concomitant N-deprotection of alkenylsulfinimines and alkenylsulfinamides as a direct route to cyclic or spirocyclic imines, pyrrolidines and piperidines

Alkenylsulfinimines and alkenylsulfinamides underwent electrophile induced cyclisation reactions with phenylselenyl bromide, iodine and bromine to cyclic and spirocyclic imines, pyrrolidines and piperidines with spontaneous cleavage of the protective group at nitrogen in good to excellent yield.     

A mild and efficient palladium-catalyzed homocoupling of lithium alkynyltriisopropoxyborates: a new route to synthesis of 1,3-diynes

Lithium alkynyltriisopropoxyborates were homocoupled in the presence of palladium acetate and DPEPhos. This protocol allows a new efficient route to synthesis of 1,3-diynes under very mild conditions.     

Construction of substituted benzene rings by palladium-catalyzed direct cross-coupling of olefins: a rapid synthetic route to 1,4-naphthoquinone and its derivatives

Ring the changes: The direct cross-coupling of electron-deficient 1,4-benzoquinone or its derivatives with electron-rich alkyl vinyl ethers proceeds in a tandem manner to produce substituted benzene rings with good selectivity and in good to excellent yields. The reaction has the potential for the rapid synthesis of diverse substituted benzene rings as it is not limited by substituent effects.     

Addition of lithium aluminium hydride to olefins catalyzed by zirconium tetrachloride: A convenient route to alkanes and 1-haloalkanes from 1-alkenes

Lithium aluminium hydride adds to olefins in the presence of zirconium tetrachloride under mild conditions. This facile reaction offers a convenient laboratory method for the hydrogenation of olefins or for the preparation of 1-haloalkanes from olefins in high yield. Unstrained internal olefins appear to be unreactive.     

A new route to 3,4-disubstituted piperidines: formal synthesis of (−)-paroxetine and (+)-femoxetine

A new route to 3,4-disubstituted piperidines was developed using chiral 1,4-dihydropyridines as key intermediates, the synthetic utility of which was demonstrated by formal synthesis of (−)-paroxetine and (+)-femoxetine.     

Determination of salbutamol by direct chiral reversed‐phase HPLC using teicoplanin as stationary phase and its application to natural water analysis

A direct chiral LC‐UV method was optimized for the determination of salbutamol (SAL) β₂‐agonist in environmental water. Two commercially available columns were evaluated: teicoplanin Chirobiotic‐T? (150 × 2.1 mm i.d., 5 µm) and vancomycin Chirobiotic‐V? (150 × 2.1 mm i.d., 5 µm). Finally, teicoplanin chiral stationary phase was selected for SAL enantiomer resolution. In order to preserve its integrity and maintain the column performance for longer time, the use of additives such as triethylamine (TEA) in the mobile phase was avoided. Experimental design was applied to simultaneously evaluate the influence of several parameters involved in enantiomer separation and to establish the conditions for acceptable resolution and performance in short analysis time. Optimum mobile phase was methanol–20 mM ammonium acetate buffer at pH 4.5 (98:2, v/v). A solid‐phase extraction procedure for sample pre‐concentration and clean‐up allowed the determination of chiral SAL residues in natural water samples spiked at low concentrations in the range 1.0–20 ng mL^?1. Reproducible recoveries, between 77 and 98%, were obtained and matrix effect was negligible. Injection of sample solutions at low elution strength permitted the SAL enantioresolution in the natural water complex matrix with satisfactory sensitivity and precision. Copyright © 2013 John Wiley & Sons, Ltd.     

A new route to diastereomerically pure cyclopropanes utilizing stabilized phosphorus ylides and gamma-hydroxy enones derived from 1, 2-dioxines: mechanistic investigations and scope of reaction

A new chemical transformation for the construction of diversely functionalized cyclopropanes utilizing 1,2-dioxines and stabilized phosphorus ylides as the key precursors is presented. Through a series of mechanistic studies we have elucidated a clear understanding of the hitherto unknown complex relationship between 1, 2-dioxines 1a-e, and their isomeric cis/trans gamma-hydroxy enones (23 and 21a-e), cis/trans hemiacetals 24a-e, and beta-ketoepoxides (e.g., 26), and how these precursors can be utilized to construct diversely functionalized cyclopropanes. Furthermore, several new synthetically useful routes to these structural isomers are presented. Key features of the cyclopropanation include the ylide acting as a mild base inducing the ring opening of the 1,2-dioxines to their isomeric cis gamma-hydroxy enones 23a-e, followed by Michael addition of the ylide to the cis gamma-hydroxy enones 23a-e and attachment of the electrophilic phosphorus pole of the ylide to the hydroxyl moiety, affording the intermediate 1-2lambda(5)-oxaphospholanes 4 and setting up the observed cis stereochemistry between H1 and H3. Cyclization of the resultant enolate (30a or 30b), expulsion of triphenylphosphine oxide, and proton transfer from the reaction manifold affords the observed cyclopropanes in excellent diastereomeric excess. The utilization of Co(SALEN)(2) in a catalytic manner also allows for a dramatic acceleration of reaction rates when entering the reaction manifold from the 1,2-dioxines. While cyclopropanation is favored by the use of ester-stabilized ylides, the use of keto- or aldo-stabilized ylides results in a preference for 1,4-dicarbonyl formation through a competing Kornblum-De La Mare rearrangement of the intermediate hemiacetals. This finding can be attributed to subtle differences in ylide basicity/nucleophilicity. In addition, the use of doubly substituted ester ylides allows for the incorporation of another stereogenic center within the side chain. Finally, our studies have revealed that the isomeric trans gamma-hydroxy enones and the beta-keto epoxides are not involved in the cyclopropanation process; however, they do represent an alternative entry point into this reaction manifold.