10405-85-3

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The reduction of a series of alkyl mesylates, dimesylates and triflates to the corresponding hydrocarbons was efficiently performed using a reducing system composed of CuCl2·2H2O, an excess of lithium sand and a catalytic amount (5 mol%) of 4,4′-di-tert-butylbiphenyl (DTBB), in tetrahydrofuran at room temperature. The process was also applied to enol and dienol triflates affording alkenes and dienes, respectively. The use of the deuterated copper salt CuCl2·2D2O allowed the simple preparation of the corresponding deuterated products.

- The alcoholate-promoted dehydrohalogenation of 5-nonyl fluoride and cyclododecyl fluoride, typical straight-chain and, respectively, medium-size cyclic substrates, leads to cis- and trans-alkenes in an approximate ratio of 1:3.With bulky bases such as lithium diisopropylamide the trans isomer may be obtained almost exclusively.In general, the elimination of hydrogen fluoride proceeds very slowly.Increase of the base strength has only a moderate effect on the rates.Electrophilic assistance as provided by lithium cations in media of low polarity can, however, considerably accelerate the reaction. - Cyclododecyl fluoride cannot be prepared from cyclododecanol.It is, however, readily accessible by bromofluorination of cyclododecene and subsequent reduction of the adduct with stannane.

Vacuum Flash Pyrolysis (VFP) at ca. 450-500 deg C and ca. 0.1-0.3 Torr of spirocyclic malonyl peroxides (2a,b) affords high yields of allenes (5a,b), while the simple malonyl peroxide (2c) leads to ketone (4), derived respectively from decarboxylation of the intermediary α-lactones (3).

Complexes of the type of have been prepared by the reaction of bis-(?-allylpalladiumchloride) with phosphorous acid disubstituted ethers; their structure has been studied by IR- and NMR- spectroscopy and X-ray analysis.The complexes have a dimeric centro-symmetric structure which is usual for bivalent palladium compounds with a slightly distorted flat-square coordination of the central atom.These compounds are active catalysts for hydrogenation of unsaturated compounds.Complexes of biphosphites of sugars can impart asymmetry in hydrogenation of prochiral substrates.

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The catalytic performances of molecular and silica-supported molybdenum oxo alkylidene species bearing anionic O ligands [ORF9, OTPP, OHMT - where ORF9 = OC(CF3)3, OTPP = 2,3,5,6-tetraphenylphenoxy, OHMT = hexamethylterphenoxy] with different σ-donation a

Methanol, ethanol, and i-propanol were converted under methanol-to-gasoline (MTH)-like conditions (400°C, 1-20 bar) over zeolite H-ZSM-5. For methanol and ethanol, the catalyst lifetimes and conversion capacities are comparable, but when i-propanol is use

The addition of N-chlorophthalimide (1b) to alkenes 3 via phthalimidyl radicals introduces a chlorine atom and an imidyl moiety to vicinal C-atoms of a carbon chain. The yields depend on the substituents of the alkene 3. The regioselectivity can be explained by steric and electronic effects; differences in the behavior of the addition of N-chlorophthalimide (1b) and N-bromophthalimide (1a) can be explained by a reversible attack of the phthalimidyl radical to the double bond.

The reductive deoxygenation of ketones and secondary alcohols to the corresponding methylene hydrocarbons has been achieved in good to excellent yield by the combined action of an aluminum hydride source and a strongly Lewis-acidic aluminum reagent.Such reductions were successful with diaryl ketones, alkyl aryl ketones, and dialkyl ketones, as exemplified by the reduction of benzophenone, acetophenone and 5-nonanone, respectively.The corrresponding secondary alcohols of these ketones, namely benzhydrol, 1-phenyl-1-ethanol, and 5-nonanol, could also be converted into their respective methylene hydrocarbons by Lewis-acidic sources of aluminum hydride.All such reductions of ketones could be conducted in a single reaction flask in a one-, two-, or three-step process.In the one-step process, which is most suitable for diaryl ketones, i-BuAlCl2 may be employed as both the hydride source and the Lewis acid.For alkyl aryl ketones a two-step process, consisting first of reduction with i-Bu2AlH and then treatment with AlBr3 (with or without catalysis of Cp2TiCl2), leads to better yields.Finally, for dialkyl ketones a three-step process proved to be preferred, wherein a sequential treatment with i-Bu2AlH, AlBr3 and then additional i-Bu2AlH (with a Ni(acac)2 catalyst) gives the highest conversion to alkane.If required, residual alkene may be removed by a brief catalytic hydrogenation or treatment with BH3THF.The ease of deoxygenating the foregoing ketones and secondary alcohols appears to be governed by the ease of forming, and the relative stability of, the corresponding carbenium ion intermediates, namely Ar2HC+ > ArRHC+ > R2HC+.The driving force for such deoxygenations by these aluminum reagents undoubtedly is the exothermic formation of the dialuminoxane system, R2Al-O-AlR2.

Aldehydes and ketones are converted into the corresponding alkenes via hydroboration of their enamines.Hydroboration of aldehyde enamines by 9-borabicyclononane (9-BBN), followed by methanolysis, affords the corresponding terminal alkenes in 75-90percent yields.Unsaturated aldehyde enamines produce the corresponding dienes under these conditions.Enamines derived from substituted cyclic ketones and heterocyclic ketones are readily accommodated in this reaction to afford the corresponding alkenes in very good yields.The synthesis of pure (Z)- or (E)-alkenes is readily achieved from the same acyclic ketone enamine by modification of the hydroboration-elimination procedure: (A) hydroboration by 9-BBN followed by methanolysis or (B) hydroboration by borane methyl sulfide (BMS) followed by methanolysis and hydrogen peroxide oxidation.Mechanistic rationale is provided.

The reactions of cis-α-epoxysilanes (1) with an excess of alkyllithium reagents were found to cleanly provide 1,2-dialkylvinylsilanes (3).A model for this reductive alkylation is advanced which explains the role of substituents in determining the product stereochemistry.

Many metallic sulphates and hydrogen sulphates supported on silica gel efficiently catalyse dehydration of secondary and tertiary alcohols under mild conditions.The sulphates of CeIV, TiIV, and FeIII were most active.Silica gel was essential for the efficient dehydration in each case.The dehydration catalysed by Fe2(SO4)3, CuSO4, and NaHSO4 on silica gel was studied in detail.The order of the reactivity of alcohols was tertiary > secondary > primary.The dehydration activity of methanesulphonic acid was also enhanced (ca. 14 times at 90 deg C) by the presence of silica gel.Some mechanistic investigations were carried out.

The α-phenylthiosilanes (2) have been used to prepare the α-silyl anions (1) by reaction with lithium naphthalenide; subsequent condensation with a carbonyl compound gave the alkene (8) via the Peterson reaction.The α-phenylthiosilanes (2) were prepared from n,n-bis(phenylthio)acetals (4) by reaction with lithium naphthalenide and chlorotrimethylsilane.The n,n-bis(phenylthio)acetals (4) were obtained, in turn, from 1,1-bis(phenylthio)acetals (5) by anion formation with butyl-lithium-N,N,N',N'-tetramethylethylenediamine complex in hexane followed by reaction with an alkyl halide.The Peterson reaction was also used to prepare vinyl sulphides (9) and vinyl sulphones (13).

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Treatment of secondary-alkyl phenyl selenides with various oxidants affords the corresponding trans-alkene highly selectively irrespective of the amount of oxidant, while in the case of the tellurium analogues the double bond geometry of the product alkene depends markedly on the amount of oxidant, the trans-isomer being formed highly selectively with 1 equiv. oxidant and the proportion of the cis-isomer being increased with excess (2-10 equiv.) of oxidant.

A new synthetic metod of preparation of alkenes with good yields, using formamide as phase transfer catalyst is described.

Highly reactive lithium dialkyl cuprates and 1-bromo-1-cyclopropylalkanes, 4, react to give good yields of the homoallylic substitution product, 6.Less reactive organocuprates react with 4 to give mixtures of 6 and the direct substitution product 7.These results are consistent with a copper(I) radical intermediate which undergoes facile rearrangement prior to reductive coupling.

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Olefins or diolefins with the double bonds in predetermined positions are obtained in moderate to good yields by treatment of α-chlorocarbonyl compounds with Grignard reagents and lithium in a single process.

Approximate rates of the competing syn- and anti-pathways have been determined in t-C4H9OK-t-C4H9OH promoted elimination from two homologous series of tosylates: I-OTs -> trans-III ( R=H, CH3, C2H5, n-C3H7, i-C3H7, t-C4H9) and II-OTs -> trans-IV ( R=CH3, C2H5, n-C3H7, i-C3H7, t-C4H9).A comparison has been made with rates of the same processes in the elimination of the corresponding trimethylammonium salts: I-N(+)(CH3)3 -> trans-III and II-N(+)(CH3)3 -> trans IV.The title effect is demonstrated by a comparative analysis of the rate patterns obtained for the two leaving groups.

The effect of 18-crown-6-ether upon geometrical orientation and rates was investigated in tert-C4H9OK-tert-C4H9OH promoted anti-elimination from two homologous series of tosylates, RCH2CHOTsC5H11 and RCHOTsCH2C5H11 (R = H, CH3, C2H5, n-C3H5, iso-C3H7, tert-C4H9).Steric requirements of the cis- and trans-stereoselective base species operating in the reaction in the absence and in the presence of the crown ether, respectively, have been assessed.An unambiguous distinction has been made between two pending models of the cis-stereoselective (ion-paired) base.