Addition Of Organolithium Reagents Research Articles

Trigonal Bipyramidal Rhodium(I) Methyl and Phenyl Complexes: Precursors of Oxidative Methyl and Phenyl Radical Generation

The new complexes [Rh(Me)(trop3P)] (2) and [Rh(Ph)(trop3P)] (3) (trop = 5H-dibenzo[a,d]cyclohepten-5-yl) were synthesised by addition of organolithium reagents (MeLi and PhLi) to the parent pentacoordinated chloride complex [RhCl(trop3P)]. The compounds have a trigonal bipyramidal structure with olefin-only ligands in the equatorial position and the methyl or phenyl substituent in the axial position. Oxidation of complexes 2 and 3 leads to the liberation of methyl and phenyl radicals, which were indirectly detected by reaction with common spin trapping reagents.

ChemInform Abstract: Catalytic Asymmetric Addition of Organolithium Reagents to Aldehydes.

Copyright © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Herein we report an efficient catalytic system for the titanium-promoted enantioselective addition of organolithium reagents to aldehydes, based on chiral Ar-BINMOL ligands. Unprecedented yields and enantioselectivities are achieved in the alkylation reactions of aliphatic aldehydes. Remarkably, methyllithium can be added to a wide variety of aromatic and aliphatic aldehydes, providing versatile chiral methyl carbinol units in a simple one-pot procedure under mild conditions and in very short reaction times.

Catalytic Asymmetric Addition of Organolithium Reagents

Catalytic Asymmetric Addition of Organolithium Reagents

ChemInform Abstract: Stereoselective Access to β‐C‐Glycosamines by Nitro‐Michael Addition of Organolithium Reagents.

The nitro-Michael addition of organolithium species to 2-nitroglycal derivatives was investigated. This methodology affords straightforward and stereoselective access to C-nitroglycosides, which are excellent precursors to C–N-acetylglycosamines. The corresponding products bearing an aromatic, heteroaromatic, alkynyl, alkenyl, or alkyl moiety were isolated in good yields with excellent selectivities. The β isomer was isolated as a single stereoisomer in most cases, and the structure was clearly elucidated by NMR spectroscopy experiments.

Stereoselective Access to β‐C‐Glycosamines by Nitro‐Michael Addition of Organolithium Reagents

AbstractThe nitro‐Michael addition of organolithium species to 2‐nitroglycal derivatives was investigated. This methodology affords straightforward and stereoselective access to C‐nitroglycosides, which are excellent precursors to C–N‐acetylglycosamines. The corresponding products bearing an aromatic, heteroaromatic, alkynyl, alkenyl, or alkyl moiety were isolated in good yields with excellent selectivities. The β isomer was isolated as a single stereoisomer in most cases, and the structure was clearly elucidated by NMR spectroscopy experiments.

Very Simple One-Step Synthesis of Vinylphosphonates and Enamine Phosphonates by Direct Addition of Organolithium Reagents to 1-Alkynylphosphonates

Direct addition of organolithium to 1-alkynylphosphonates (1) afforded vinylphosphonates and enamine phosphonates (2) in good to excellent yields. The reaction was carried out in dry THF at low temperature and proved to be completely stereoselective (syn addition). Alkyl, aryl, and haloalkyl groups were attached to the alkynyl entity, so the resulting vinylphosphonates contained various functional groups. The stereochemistry of the products as well as mechanism of the reaction were determined based on 1H and 13C NMR. The synthesis of enamine phosphonates in the absence of complicated, highly expensive organometallic catalysis has not been previously reported.

ChemInform Abstract: Highly Regioselective Control of 1,2‐Addition of Organolithiums to α,β‐Unsaturated Compounds Promoted by Lithium Bromide in 2‐Methyltetrahydrofuran: A Facile and Eco‐Friendly Access to Allylic Alcohols and Amines.

AbstractLithium bromide‐mediated addition of organolithium reagents towards α,β‐unsaturated aldehydes and ketones proceeds with excellent 1,2‐chemoselectivity to give the corresponding allylic alcohols (III) and (V) in high yields.

ChemInform Abstract: Application of Indium Ate Complexes to Synthetic Chemistry. Selective Conjugate Addition to Enones and Coupling with Allylic Halides.

Tetraorganoindium ate complexes, prepared by the addition of organolithium reagents to trialkylindium, reacted with α,β-unsaturated ketones in a 1,4-addition fashion; allylic indates derived from allylic indium sesquihalides coupled with allylic halides regio- and stereo-specifically to give high yields of head-to-tail 1,5-dienes.

ChemInform Abstract: Stereoselective Bis-functionalizations of Arene Chromium Tricarbonyl Complexes via Brook Rearrangements.

An efficient method has been developed for the stereoselective bis-functionalization of arene chromium tricarbonyl complexes. Initial nucleophilic addition of organolithium reagents to a carbonyl moiety is followed by a 1,4-carbon to oxygen silyl migration (Brook rearrangement) and alkylation of the resultant aryl anion.

Regiospecific synthesis of α-chloro- and α-fluoro-1,2-diones

α-Chloro-1,2-diones and α-fluoro-1,2-diones were prepared from the corresponding α-chloroaldimines by a sequence of reactions involving cyanation to α-cyanoenamines, α-halogenation to form α-chloro- or α-fluoroimidoyl cyanides and addition of organolithium reagents across the nitrile moiety, followed by acidic hydrolysis. All steps are straightforward and occur without side reactions finally leading to regiospecifically chlorinated and fluorinated 1,2-diones in good yields.

Synthesis and Biological Evaluation of Novel 1′‐Branched and Spironucleoside Analogues

Novel anomeric spironucleosides and 1′‐cyano‐2′,3′‐didehydro‐2′,3′‐dideoxyuridine, a structural analogue of known anti‐HIV agents, were prepared by nucleophilic addition of organolithium reagents to 1′‐cyano‐2′‐deoxy‐ and 1′‐cyano‐2′‐deoxy‐2′β‐bromo‐uridine derivatives, respectively. The yield and distribution of products depended on the reaction conditions, which were studied in detail. Although none of the compounds exhibited antiviral activity, two compounds displayed cytostatic activity against both murine leukemia and human T‐lymphocyte cells. †Also corresponding author.

Pyrrolodiazines. 5. Synthesis, Structure, and Chemistry of Pyrrolo[1,2-c]pyrimidine. Dipolar Cycloaddition of Pyrrolo[1,2-c]pyrimidinium Ylides

An improved synthesis of pyrrolo[1,2-c]pyrimidines, including the parent system, was accomplished via sequential condensation of substituted pyrrole-2-carboxaldehydes with tosylmethyl isocyanide (TOSMIC), followed by desulfonylation of the formed tosylpyrrolo[1,2-c]pyrimidines. Based on the ab initio calculations performed on the pyrrolo[1,2-c]pyrimidine 1a, some of the basic chemistry was investigated, including electrophilic substitution, addition of organolithium reagents, metalation with lithium diisopropylamide (LDA) and subsequent reaction with electrophiles, and formation of salts by quaternization of the nonbridgehead nitrogen. Azomethine ylides generated from pyrrolo[1,2-c]pyrimidinium salts undergo 1,3-dipolar cycloaddition with suitable dipolarophiles to give new dipyrrolo[1,2-a;1‘,2‘-c]pyrimidine derivatives, with high regio- and stereoselectivity.

Pyrrolodiazines. 2. Structure and Chemistry of Pyrrolo[1,2-a]pyrazine and 1,3-Dipolar Cycloaddition of Its Azomethine Ylides.

A new synthesis of the pyrrolo[1,2-a]pyrazine system from pyrrole is described. In light of the ab initio calculations carried out on this heterocyclic system some of its basic chemistry was investigated and included electrophilic substitution, addition of organolithium reagents, metalation with lithium diisopropylamide and subsequent reaction with electrophiles, and formation of salts by quaternization of the nonbridgehead nitrogen. N-ylides obtained from these salts undergo 1,3-dipolar cycloaddition with suitable dipolarophiles to give dipyrrolo[1,2-a]pyrazines, pyrazolo[1,5-a]-pyrrolo[2,1-c]pyrazines, and heterobetaines. Examples of intramolecular 1,3-dipolar cycloadditions are also reported.

ChemInform Abstract: Cerium(III) Chloride Promoted Nucleophilic Addition of Organolithium Reagents to α‐Diphenylphosphinoyl Ketones. An Efficient Method for the Synthesis of Horner‐Wittig Intermediates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Stereoselective Conjugate Addition of Organolithium Reagents to Enolates Derived from Glyceraldehyde Acetonide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Oxygenophilic organoaluminium-promoted 1,4-addition of organolithium reagents to quinone monoacetals

Complexation of quinone monoacetals with methylaluminium bis-(2,6-di-t-butyl-4-methylphenoxide), followed by addition of organolithium reagents, gives products from 1,4-addition of the organolithium reagent to the quinone monoacetal.

Unexpected regioselective nucleophilic addition to 3-(4,4-dimethyloxazolin-2-yl)-pyridine: formation of stable 1,4-dihydropyridines

The regioselective addition of organolithium reagents to 3-(4,4-dimethyloxazolin-2-yl)pyridine leads to stable 1,4-dihydropyridines.

Addition of organolithium reagents to α-chlorovinyltri-methylsilane

Abstract α-Chlorovinyltrimethylsilane adds n- and t-butyllithium to form 1-trimethylsilyl-1-hexene and 3,3-dimethyl-1-trimethylsilyl-1-butane, where its reaction with phenyllithium affords mainly phenyltrimethylsilane and ethynyltrimethyl-silane.

A novel synthesis of 2-lithio derivatives of 2-substituted-1,3-dithianes. The addition of organolithium reagents to trimethylenedithio-carbene and to 2-methylene-1,3-dithiane

A novel synthesis of 2-lithio derivatives of 2-substituted-1,3-dithianes. The addition of organolithium reagents to trimethylenedithio-carbene and to 2-methylene-1,3-dithiane