Catalytic Amount Of Naphthalene Research Articles

Isolation and Reactivity of a Digerma Analogue of Vinyllithiums: a Lithium Digermenide

The versatile reactivity of disilenides, heavier analogues of vinyl anions, opened the door to novel heavier group 14 structure motifs with residual functionalities in the periphery around the Si═Si moiety. The corresponding germanium analogue, digermenide Tip2Ge═Ge(Tip)Li·dme2 (Tip = 2,4,6-triisopropylphenyl, dme = 1,2-dimethoxyethane), has now been obtained from the reduction of Tip2GeCl2 with 3.3 equiv of Li powder and a catalytic amount of naphthalene in dme at −70 °C. The lithium digermenide was characterized by NMR spectroscopy, UV/vis spectroscopy, X-ray diffraction, and DFT calculations. As proof of principle for its suitability for the nucleophilic transfer of the Ge═Ge motif, the reaction with chlorosilanes leads to the unsymmetrically substituted digermenes Tip2Ge═Ge(Tip)SiR3.

Reductive Removal of the Pivaloyl Protecting Group from Tetrazoles by a Naphthalene-Catalyzed Lithiation Process

The reaction of various 1-pivaloyl-1H-tetrazoles with excess lithium and a catalytic amount of naphthalene (20 mol%) led, after treatment with methanol, to the corresponding free tetrazoles through reductive C–N bond cleavage. This methodology represents a reasonable alternative to other nonreductive protocols.

Active-alkali metal-promoted reductive cleavage of chlorinated phenols

We investigated the degradation of chlorinated phenols under reductive electron transfer reaction conditions. Although Li and Na metal proved useless, activated forms of these metals, either their soluble naphthalene radical anions or 1,2-diarylethane dianions, promoted the degradation of the starting materials to various extents. Additionally, efficient dehalogenation of the sodium salts of several mono-, di-, and tri-chlorophenols was obtained by their reduction with an excess of Na metal and a catalytic amount of naphthalene. .

ChemInform Abstract: New Trimethylenemethane Dianion Synthons: Application to the Preparation of Substituted Perhydrofuro[2,3-b]furans.

Abstract The reaction of 3-chloro-2-(chloromethyl)prop-1-ene ( 1 ) with lithium powder and a catalytic amount of naphthalene in the presence of different electrophiles in THF at −78°C yields products 2 . When carbonylic compounds are used as electrophiles the corresponding methylenic diols are obtained, which by tandem hydroboration–oxidation with alkaline hydrogen peroxide and treatment with PCC (for ketone derivatives) or (Ph 3 P) 3 RuCl 2 (for aldehyde derivatives) furnish the expected perhydrofurofurans 3 . Using 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene ( 4 ) as starting material and under the above conditions, the selective chloro/lithium exchange versus the allylic carbon–oxygen bond cleavage allows the introduction of a first electrophile at −78 to −30°C, and a second electrophile at −30°C to room temperature to give products 5 . The same oxidation protocol mentioned above, when applied to diols 5 , lead to the differently substituted perhydrofurofurans 7 .

ChemInform Abstract: Substituted Perhydrofuropyrans: Easy Preparation from 2-Chloromethyl-3-(2-methoxyethoxy)propene Through 3-Methylene-1,6-diols.

Abstract The reaction of 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene ( 1 ) with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E 1 =R 1 R 2 CO) in THF at −78 to 0°C, followed by treatment with an epoxide [E 2 =R 3 R 4 C(O)CHR 5 ] at 0 to 20°C leads, after hydrolysis, to the expected unsaturated diols 2 . When some compounds 2 ( 2e – h ) are successively hydroborated (BH 3 ·THF) and oxidised (33% H 2 O 2 and then PCC), the expected perhydrofuropyrans 3e – h are isolated directly.

A 1,3-sp2,sp3-hybridized dilithio intermediate by direct lithiation of cyclopropylidene diphenylmethane

The reaction of cyclopropylidene diphenylmethane 1 with an excess of lithium and a catalytic amount of naphthalene (5 mol %) at -20 oC, followed by addition of an electrophile [E = H2O, D2O, t-BuCHO, Me2CO, Et2CO, n-Pr2CO, i-Pr2CO, (c-C3H5)2CO, (CH2)5CO] at -78 oC and final hydrolysis with water at -78 oC to rt gives the corresponding products 5, which in some case are contaminated with the corresponding by-products 6, resulting from the incorporation of only one electrophilic moiety at the intermediate dianion of type 2. The separation of both reaction products is easy by simple column chromatography.

Deacylation of Esters, Thioesters and Amides by a Naphthalene-Catalysed Lithiation

The reaction of different esters, thioesters and amides derived from pivalic, benzoic and 4-tert-butylbenzoic acids with an excess of lithium and a catalytic amount of naphthalene (8 mol%) led, after methanolysis, to the corresponding alcohols, thiols and amines, respectively, through a reductive non-hydrolytic procedure. This methodology represents a reasonable alternative to other non-reductive protocols.

Desilylation procedure via a naphthalene-catalysed lithiation reaction

The reaction of silyl protected alcohols, amines and thiols with lithium powder and a catalytic amount of naphthalene, in THF, at 0 °C led, after hydrolysis, to the recovery of the free alcohols, amines and thiols in very good yields. At least a phenyl group was required in the silyl protecting group for the success of the reaction. Some polyfunctionalised starting materials have successfully been deprotected. The stereochemical outcome of the deprotection of a silylated chiral secondary alcohol has also been studied and no racemization was observed. The process has shown to be a good alternative to the acid-catalysed desilylation procedures, the latter being not useful for the deprotection of some silylated tertiary alcohols.

Straightforward Synthesis of 1,7‐Dioxaspiro[4.4]nonanes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Straightforward synthesis of 1,7-dioxaspiro[4.4]nonanes

The reaction of 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E 1=R 1R 2CO) in THF at −78 to 0 °C, followed by the addition of an epoxide [E 2=R 3R 4C(O)CHR 5] at 0 to 20 °C leads, after hydrolysis, to the expected methylidenic diols. These diols, in the presence of iodine and silver(I) oxide in dioxane–water, undergo double intramolecular iodoetherification to give the corresponding 1,7-dioxaspiro[4.4]nonanes, which in addition can be easily oxidised to a variety of 1,7-dioxaspiro[4.4]nonan-6-ones.

Practical generation of 3,5‐dimethoxybenzyllithium: application to the synthesis of 5‐substituted‐resorcinols

AbstractReductive lithiation of 3,5‐dimethoxybenzyl methyl ether was successfully performed with lithium wire and a catalytic amount of naphthalene in dry tetrahydrofuran at −15°C, leading to the quantitative generation of 3,5‐dimethoxybenzyllithium. This organometallic compound, which can be stored for at least 24 h, was trapped with a variety of different electrophiles, including, besides aldehydes, non‐functionalized and functionalized alkyl halides and an epoxide. Accordingly, it is a useful intermediate in the synthesis of 5‐substituted natural and non‐natural resorcinols. Copyright © 2003 John Wiley & Sons, Ltd.

Straight and Versatile Synthesis of Substituted Perhydrofuro[2,3‐b]pyrans from 2‐Chloromethyl‐3‐(2‐methoxyethoxy)propene.

Abstract The reaction of 2-chloromethyl-3-(2-methoxyethoxy)propene with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E1=R1R2CO) in THF at −78 to 0°C, followed by the addition of an epoxide [E2=R3R4C(O)CHR5] at 0 to 20°C leads, after hydrolysis, to the expected methylidenic diols. These diols when subjected to successive hydroboration–oxidation and further oxidation, spontaneous cyclization occurs to furnish a series of differently substituted perhydrofuro[2,3-b]pyrans.

Straight and versatile synthesis of substituted perhydrofuro[2,3- b]pyrans from 2-chloromethyl-3-(2-methoxyethoxy)propene

The reaction of 2-chloromethyl-3-(2-methoxyethoxy)propene with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E 1=R 1R 2CO) in THF at −78 to 0°C, followed by the addition of an epoxide [E 2=R 3R 4C(O)CHR 5] at 0 to 20°C leads, after hydrolysis, to the expected methylidenic diols. These diols when subjected to successive hydroboration–oxidation and further oxidation, spontaneous cyclization occurs to furnish a series of differently substituted perhydrofuro[2,3- b]pyrans.

The NiCl2‐Li‐Arene (cat.) Combination as Reducing System. Part 9. Catalytic Hydrogenation of Organic Compounds Using the NiCl2‐Li‐(Naphthalene or Polymer‐Supported Naphthalene) (cat.) Combination.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Benzyllithium from methylated benzylamine and its ammonium salt via naphthalene-catalyzed carbon-nitrogen bond reductive cleavage

The reaction of N,N-dimethylbenzylamine with lithium powder and a catalytic amount of naphthalene, followed by addition of different electrophiles, gave the expected reaction products in low yield. However, yields could be improved by using the corresponding ammonium salt instead of the amine. When N,N,N-trimethylbenzylammonium iodide was submitted to the naphthalene-catalyzed lithiation process, followed by reaction with several electrophiles, the expected reaction products were obtained in moderate to good yields.

The NiCl2‐Li‐Arene (cat.) Combination as Reducing System, Part 9: Catalytic Hydrogenation of Organic Compounds using the NiCl2‐Li‐(Naphthalene or Polymer‐Supported Naphthalene) (cat.) Combination

AbstractThe reaction of lithium powder, a catalytic amount of naphthalene or polymer‐supported naphthalene, and anhydrous nickel(II) chloride, in THF at room temperature, generates a finely divided and very reactive nickel(0) which has been efficiently applied to the catalytic hydrogenation of different organic compounds such as alkenes, alkynes, carbonyl compounds, imines, organic halides, aromatic compounds, hydrazines, azoxy compounds, and N‐oxides.

The Hydrogenation of Cyclododecene by Lithium Naphthalenide and Nickel Chloride Dihydrate

A simple alternative method to the catalytic hydrogenation of cyclododecene is reported. It is based on the reductive system composed of nickel(II) chloride dihydrate, lithium, and a catalytic amount of naphthalene. This combination for the reduction of olefins avoids the handling of molecular hydrogen, the water contained in the nickel salt being the source of hydrogen.

Generation of allylic and benzylic organolithium compounds by fluorine–lithium exchange: reaction with electrophiles

The application of the naphthalene-catalysed lithiation methodology to allylic and benzylic fluorides 1 led to the corresponding allylic and benzylic organolithium reagents, which, in the presence of different electrophiles (Barbier-type reaction conditions), afforded the expected products 2 in moderate yields. The procedure was useful for the transformation of primary, secondary and tertiary benzylic fluorides into the corresponding lithium derivatives. When a two-step lithiation process was used (treatment of fluoride 1 with lithium and a catalytic amount of naphthalene, followed by addition of the electrophilic reagent), only Wurtz-type coupling products were formed.

ChemInform Abstract: Generation and Reactivity of α-Amino-Substituted Arylmethyllithium Organometallics.

Abstract Reductive cleavage of open chain and cyclic α- N , N -dialkylamino-substituted benzyl alkyl ethers 1a – f with a dispersion of Li metal and a catalytic amount of naphthalene in THF, allowed easy access to a wide array of α- N , N -dialkylamino-substituted benzyllithium derivatives. Reaction of these organometallics with various electrophiles afforded the expected products in satisfactory yields.

Generation and Reactivity of α-Amino-Substituted Arylmethyllithium Organometallics

Reductive cleavage of open chain and cyclic α-N,N-dialkylamino-substituted benzyl alkyl ethers 1a–f with a dispersion of Li metal and a catalytic amount of naphthalene in THF, allowed easy access to a wide array of α-N,N-dialkylamino-substituted benzyllithium derivatives. Reaction of these organometallics with various electrophiles afforded the expected products in satisfactory yields.