Lithio Derivative Research Articles

A direct synthesis of olefins by reaction of carbonyl compounds with lithio derivatives of 2-[alkyl- or (2′-alkenyl)- or benzyl-sulfonyl]-benzothiazoles.

During the title reaction, the lithium alkoxides formed as intermediates undergo an intramolecular addition to the neighboring CN group followed an S to 0 benzothiazole transfer and simultaneous extrustion of sulfur dioxide and ejection of 2(3H)-benzothiazolone anion.

ChemInform Abstract: Three‐Component Coupling Synthesis of Prostaglandins. A Simplified, General Procedure.

AbstractIn the presence of dimethylzinc, the lithio derivative of (Ia) can be linked to the cyclopentenone (II) to give the product (III).

ChemInform Abstract: Lithiated 2‐Methyl‐5‐phenyloxazoles, Formation and Reactions with Electrophiles.

The methyl group of 2-methyl-5-phenyloxazole (1) has been lithiated with lithium diisopropylamide (LDA) and the resulting lithio derivative has been reacted with electrophiles to obtain 2-alkyl-5-phenyloxazoles

ChemInform Abstract: An Efficient Synthesis of Alkenyl and Alkynyl Silyl Ethers.

Abstract A general synthesis of alkynyl and alkenyl silylethers is described. This involves reaction of alkynyl or alkenyl organometallic reagents, usually the lithio derivatives, with chlorodimethylaminodimethylsilane, followed by reaction of the product with an alcohol.

ChemInform Abstract: Chalcogen Derivatives of Cyclopentadienyl‐tricarbonylmanganese and ‐rhenium, ((OC)3MC5H4)2En (M: Mn, Re; E: S, Se, Te; n = 2, 1).

AbstractThe lithio derivatives of the title compounds (I) react with one equiv. S8, Se, or Te to give chalcogenolate intermediates of the type LiE‐C5H4M(CO)3, which on air oxidation are transformed into the dichalcogenides (III).

Migration du lithium en série pyridinique: double catalyse et reformage. Accès aux dérivés de la bromo-2 lithio-3 pyridine et des bromo-4 halogéno-2 lithio-3 pyridines

The lithium of an organolithio-pyridinic derivative can be moved from one position to an other by an intermolecular reaction. Two new reactions are possible for pyridinic organic synthesis: the isomerisation of any lithio derivative to a more stable one, and a reaction that transforms a mixture of various bromo-lithio derivatives into a single one. The processes involved and the experimental tools used are described in terms of the 2-bromo-3-lithio- and 4-bromo-2-halogeno-3-lithio-pyridines derivatives synthesis.

A new synthesis of .alpha.-phosphinoyl cycloalkanones by phosphinylation of cycloalkanone enolates. Crystal and molecular structure of 2-(diphenylphosphinoyl)-3-[tris(methylthio)methyl]cyclopentanone and 2-(diphenylphosphinoyl)-3-carbomethoxycyclopentanone

A new one-pot synthesis of 2-(diphenylphosphinoyl)cycloalkanones is described which involves the reaction of cyclic enolate anions with chlorodiphenylphosphine followed by oxidation with air. In an effort to synthesize sarkomycin, 2-(diphenylphosphinoyl)-3-[tris(methylthio)methyl]cyclopentanone (9) was prepared by tandem 1,4-addition of the lithio derivative of trimethyl trithioorthoformate to cyclopentenone and C-phosphinylation of the enolate anion formed. Methanolysis of 9 catalyzed by mercury salts gave 2-(diphenylphosphinoyl)-2-carbomethoxycyclopentanone (10)

Chalkogenderivative des cyclopentadienyl-tricarbonyl-mangans und -rheniums, [(CO) 3MC 5H 4] 2E n (M = Mn, Re; E = S, Se, Te; n = 2, 1)

The lithio derivatives of the half-sandwich complexes C 5H 5M(CO) 3 (M = Mn, Re) take up chalcogens E to give chalcogenolate intermediates of the type {(CO) 3MC 5H 4ELi} which, upon air oxidation, are transformed into the dichalcogenides [(CO) 3MC 5H 4] 2E 2 (E = S, Se, Te). Direct reaction of the lithio derivatives with SCl 2 gives the sulfides [(CO) 3MC 5H 4] 2S, whereas the corresponding reaction with SeCl 4 and TeCl 4, followed by reductive dehalogenation using aqueous Na 2S solution, gives the analogous selenides and tellurides, [(CO) 3MC 5H 4] 2E (M = Mn, Re; E = S, Se, Te). The phenylphosphino-substituted complexes [(CO) 3MC 5H 4] 2P(C 6H 5) (M = Mn, Re) are also described. All new compounds are characterized by their IR and mass spectra, and, in particular, by their 1H, 13C and 31P NMR spectra.

Lithiated 2-Methyl-5-Phenyloxizoles, Formation and Reactions with Electrophiles

The methyl group of 2-methyl-5-phenyloxazole (1) has been lithiated with lithium diisopropylamide (LDA) and the resulting lithio derivative has been reacted with electrophiles to obtain 2-alkyl-5-phenyloxazoles

ChemInform Abstract: A Stereospecific Convergent Coupling of Nucleophilic and Electrophilic Chiral Carbons.

AbstractThe optically active boronic ester (I) is transformed into the stannyl ether (IV), whose lithio derivative undergoes stereospecific coupling with a second molecule of (I) to give the boronate (V), a precursor of the dialcohol (VI).

ChemInform Abstract: Formylation of Estrogens.

Reimer-Tiemann formylations of oestradiol and oestrone were investigated and, whilst substitution was effected under certain conditions to give mixtures of 2- and 4-formyloestrogens, yields were very low and the method was unsuitable for preparative purposes. Regioselective methods were developed and 2-formyloestradiol was conveniently prepared from oestradiol by formylation of the lithio derivative of the bis(methoxymethyl) ether and removal of the rotecting groups with hydrochloric acid. 4-Formyloestradiol was prepared by a sequence of reactions starting with the methoxyethyl ether of 4-bromooestradiol, then metal-halogen interconversion, formylation with N-methylformanilide, and removal of the protecting group. A number of related derivatives, including 2-formyloestriol, were prepared.

Komplexchemie perhalogenierter Cyclopentadiene und Alkine: V. Darstellung weiterer funktioneller Derivate von (C 5Cl 4R)Mn(CO) 3 und (C 5Cl 4R)Rh(COD). Kristallstruktur von (C 5Cl 4CONH 2)Mn(CO) 3

Starting from (C 5Cl 4Li)Mn(CO) 3, generated in situ, the functional derivatives (C 5Cl 4R)Mn(CO) 3 with R = SnMe 3, PPh 2, SePh, (SCl 5Cl 4)Mn(CO) 3, CHO, COCl, CONH 2, CN, NCO, and NH 2 can be obtained. A series of compounds (C 5Cl 4R)Rh(1,5-COD) with R = H, Me, SiMe 3, SiMe 2H and SnMe 3 can be prepared from (C 5Cl 5)Rh(1,5-COD) via the lithio derivative. The crystal structure of (C 5Cl 4CONH 2)Mn(CO) 3 has been determined.

Oxidation and Substitution Reactions of 3-Phenyl-Δ5-1.2,3[sgrave]3-diazaphospholenes

Abstract The reaction of hydrazones with dichlorophenylphosphine in the presence of triethylamine leads to the elimination of 2 equivalents of hydrogen chloride forming the title compound(I). The oxidation of compound (I) has been examined with many oxidising agents under various experimental conditions. Mild oxidising agents like hydrogen peroxide and sulfur give the phospholene oxide and sulfide respectively, Reactions of compound (I) with oxidising agents like nitrogen oxides, sulfur dioxide and dimethyl sulfoxide result in complex reaction mixtures, even under mild reaction conditions. The hydrogens at the 4 position in compound (I) can be metallated by using n-BuLi. Studies of the substitution reactions of the lithio derivatives of compound (I) with various electrophilic reagents are in progress.

An efficient synthesis of alkenyl and alkynyl silyl ethers

A general synthesis of alkynyl and alkenyl silylethers is described. This involves reaction of alkynyl or alkenyl organometallic reagents, usually the lithio derivatives, with chlorodimethylaminodimethylsilane, followed by reaction of the product with an alcohol.

Diastereoselective addition of lithiated N,N-diethyl-o-toluamide to chiral isopropylidine glyceraldehyde lmines. Asymmetric synthesis of 3-substituted 3,4-dihydro-1(2H)-isoquinolones

The lithio derivative of N,N-diethyl-o-toluamide adds regiospecifically to (R)-and (S)-glyceraldehyde acetonide p-methoxybenzyl imines to afford the Cram-chelation controlled products (3S,1′R)-(3) and (3R,1′S)-(3),respectively.

Synthesis of naucléfine, angustidine, angustine, (±)-13b,14-dihydro-angustine and naulafine

The lithio derivatives of 3-cyano-4-methylpyridines and 6,7-dihydro-5H-2-pyrindine-4-carbonitrile react with 2,9-bis-(trimethylsilyl)-3,4-dihydropyrido[3,4-b]indolium trifluoromethanesulfonate to form cyclic amidines which, upon hydrolysis and oxidation, produce the title alkaloids.

Formylation of Estrogens

Reimer-Tiemann formylations of oestradiol and oestrone were investigated and, whilst substitution was effected under certain conditions to give mixtures of 2- and 4-formyloestrogens, yields were very low and the method was unsuitable for preparative purposes. Regioselective methods were developed and 2-formyloestradiol was conveniently prepared from oestradiol by formylation of the lithio derivative of the bis(methoxymethyl) ether and removal of the rotecting groups with hydrochloric acid. 4-Formyloestradiol was prepared by a sequence of reactions starting with the methoxyethyl ether of 4-bromooestradiol, then metal-halogen interconversion, formylation with N-methylformanilide, and removal of the protecting group. A number of related derivatives, including 2-formyloestriol, were prepared.

ChemInform Abstract: BF3‐Mediated Reaction of a Sulfone with Aldehydes. A Method for Stereospecific Construction of Prostaglandin ω‐Chain.

AbstractThe reaction of the lithio derivative of the sulfone (II), the preparation of which from (I) is described, with the ketones (III) in the presence of BF3‐etherate, gives the adducts (IV).

ChemInform Abstract: Catalyzed Metalation Applied to 2‐Methoxypyridine.

AbstractLithiation of 2‐methoxypyridine (I) with methyllithium (II) is catalyzed by diisopropylamine to proceed regioselectively at position 3, yielding the lithio derivative (III).

ChemInform Abstract: Novel 1,2‐Migration Reactions of Organometals Containing Aluminum, Zinc, and Other Main Group Metals with α‐Haloorganolithiums.

AbstractThe reaction of organoalanes such as (I) or (IV) with the lithio derivative (II) to give the products (III) or (V) is assumed to proceed via a 1,2‐migration pathway.