Organozinc Research Articles

ChemInform Abstract: Highly Regio‐ and Stereoselective Double Michael Addition—Cyclization of 2,3‐Allenoates with Organozinc Compounds: Efficient Synthesis of 5‐Benzylidenecyclohex‐2‐enones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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.

Palladium- and Nickel-Catalyzed Cross-Couplings of Unsaturated Halides Bearing Relatively Acidic Protons with Organozinc Reagents

A wide range of polyfunctional aryl, heteroaryl, alkyl, and benzylic zinc reagents were coupled with unsaturated aryl halides bearing an acidic NH or OH proton, using Pd(OAc)2 (1 mol %) and S-Phos (2 mol %) as catalyst without the need of protecting groups. A similar nickel-catalyzed reaction is described. The relative kinetic basicity of organozinc compounds as well as their stability toward acidic protons is also described.

Nickel(II)-catalyzed carbon–carbon bond formation reaction of functionalized organozinc reagents with aromatic aldehydes

In the presence of a silylating reagent and catalytic amount of Ni(acac) 2, organozinc halides reacted with aromatic aldehydes to give the corresponding dialkylation products in good to excellent yields under mild conditions.

Double Michael Addition-Cyclization of 2,3-Allenoates with Dialkylzinc

α,β-Unsaturated cyclohexenones are important building blocks in organic and medicinal chemistry. The development of an efficient highly regio- and stereoselective double addition-cyclization of two molecules of 2,3-allenoates with dialkylzinc is reported. The corresponding substituted cyclohexenones are obtained in high yields and excellent regio- and stereoselectivities. This work is an interesting example of efficient conjugate addition of organozinc compounds to double bonds.

Nickel-catalyzed organozinc-induced unexpected 1,3-migration of tert-butyl from sulfur to carbon in N- tert-butanesulfinyl iminoacetates

The nickel-catalyzed reaction for an unexpected 1,3-migration of tert-butyl from sulfur to carbon, upon treatment of functionalized N- tert-butanesulfinyl iminoacetate in the presence of organozinc reagent, was developed. The generality has been explored by considering the flexibility in the structure of each reactive component, organozinc halide and N- tert-butanesulfinyl iminoacetate.

Highly Regio‐ and Stereoselective Double Michael Addition–Cyclization of 2,3‐Allenoates with Organozinc Compounds: Efficient Synthesis of 5‐Benzylidenecyclohex‐2‐enones

Hochsubstituierte α,β-ungesättigte Cyclohexenone, ein zentrales Strukturmotiv in vielen Naturstoffen, sind mit der Titelreaktion zugänglich (siehe Schema). Die Diastereoselektivität bezüglich der beiden stereogenen Zentren (4- und 6-Position) ist hoch. Mit optisch aktiven Ausgangsmaterialien wurden die erwünschten Produkte ohne nachweisbare Racemisierung gebildet. Eine mögliche Erklärung der Stereoselektivität wird präsentiert.

Highly Regio‐ and Stereoselective Double Michael Addition–Cyclization of 2,3‐Allenoates with Organozinc Compounds: Efficient Synthesis of 5‐Benzylidenecyclohex‐2‐enones

Highly substituted α,β-unsaturated cyclohexenones, a key structural motif in many natural products, were prepared in the title reaction (see scheme). High diastereoselectivity was observed with respect to the two stereogenic centers at the 4- and 6-positions. When optically active starting materials were used, the desired products were formed without evident racemization. A rationale for the observed stereoselectivity is proposed.

ChemInform Abstract: Palladium‐Catalyzed Synthesis of Indene Derivatives via Propargylic Carbonates with in situ Generated Organozinc Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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.

Unusual interaction of perfluoroaromatic organozinc compounds with benzoyl chloride and DMF

The organozinc compounds obtained from chloropentafluorobenzene and octafluorotoluene in reactions with benzoyl chloride and DMF form N,N-dimethylbis(perfluoroaryl)methylamines; the addition of CuCl changes the direction of reaction towards the formation of corresponding polyfluoroaromatic ketones.

Photoelectron spectra of some organozinc compounds

The electronic structures of bis(pentafluorophenyl)zinc ( I) and dichloro( N, N, N′, N′-tetramethylethylenediamine)zinc(II) ( II) have been investigated by HeI and HeII UV photoelectron spectroscopy (UPS) and DFT/OVGF calculations. We discuss the properties of Zn-aryl and Zn–N bonds on the basis of spectroscopic evidence i.e. the nature of metal–ligand bonding. Our study is the first reported one on the photoelectron spectra of zinc-aryl complex.

Pd-catalyzed alkylation of halogen-substituted steroids with organozinc compounds

A general procedure has been developed for the introduction of hydrophobic alkyl groups into positions 6, 3, and 17 of steroid molecules via palladium-catalyzed Negishi reaction of halogen-substituted steroids with benzyl- and alkylzinc halides.

Reaction of organozinc reagents formed from α,α-dibromocarbonyl compounds and zinc with (3-phenylprop-2-enylidene)malonodinitriles and primary amides of 2-Cyano-5-phenylpenta-2,4-dienoic acid

Organozinc compounds formed from 1-aryl-2,2-dibromoalkanes, α,α-dibromopinacoline, and dialkyl dibromomalonates and zinc react with (3-phenylprop-2-enylidene)malonodinitriles and primary amides of 2-cyano-5-phenylpenta-2,4-dienoic acid to form 2-alkyl-2-aroyl-3-(phenylvinyl)cyclopropan-1,1-dicarboxylic acid dinitriles, N-substituted amides of 3-(phenylvinyl)-2-(2,2-dimethylpropanoyl)-1-cyanocyclopropan-1-carboxylic acids, and alkyl 3-R-6-(phenylvinyl)-2,4-dioxo-5-cyano-3-azabicyclo[3.1.0]-hexan-1-carboxylates as a single stereoisomer.

Investigation of reactions of the organozinc reagents prepared from zinc and dialkyl dibromomalonates with the derivatives of 2-arylmethyleneindan-1,3-dione and 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-dione

Organozinc compounds prepared from dialkyl dibromomalonates and zinc react with 2-arylmethyl-eneindan-4,6-diones, 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-diones, as well as with 2-[4-(1,3-dioxoindan-2-ylidenemethyl)phenyl]methyleneindan-1,3-dione and 5-[4-(2,2-dimethyl-4,6-dioxo-1,3-dioxane-2-ylidenemethyl)phenyl]methylene-2,2-dimethyl-1,3-dioxane-4,6-diones to form dialkyl 3-aryl-1′3′-dioxaspiro(cyclopropane-2,2′-indan)-1,1-dicarboxylates, dimethyl 3-aryl-6,6-dimethyl-5,7-dioxa-4,8-dioxaspiro[2,5]octan-2,2-dicarboxylates, dialkyl 2-{4-[3,3-bis (alkoxycarbonyl)-1′,3′-dioxaspiro(cyclopropane-2,2′-indan)-1-yl]phenyl}-1′,3′-dioxaspiro[cyclopropane-2,2′-indan]-1,1-dicarboxylates, and dialkyl 2-{4-[2,2-bis(alkoxycarbonyl)-6,6′-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]oct-1-yl]phenyl}-6,6-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]octan-1,1-dicarboxylate respectively.

Radical–polar crossover domino reactions involving organozinc reagents and β-(allyloxy)-enoates

Organozinc reagents (organozinc halides, diorganozincs and mixed copper–zinc reagents) react with β-(allyloxy)-enoates via a radical–polar crossover process to afford substituted furans in one single synthetic step following a domino reaction involving Michael addition and carbocyclisation. Reversal of diastereoselectivity can be obtained varying the organometallic and/or the reaction conditions.

ChemInform Abstract: Alkylation of Aryl N‐(2‐Pyridylsulfonyl)aldimines with Organozinc Halides: Conciliation of Reactivity and Chemoselectivity.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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.

Alpha-olefins as alkenylmetal equivalents in catalytic conjugate addition reactions.

Alpha-olefins as alkenylmetal equivalents in catalytic conjugate addition reactions.

Nickel-Catalyzed Asymmetric Negishi Cross-Couplings of Secondary Allylic Chlorides with Alkylzincs

Complementing previous advances in allylation chemistry, an effective nickel/Pybox catalyst for regioselective asymmetric Negishi cross-couplings of racemic secondary allylic chlorides with readily available organozinc halides has been developed. The method has been applied in two key steps of a formal total synthesis of fluvirucinine A1.

Organozinc reagents from polyfluoroarenes: Preparation and reactions with allyl halides. Synthesis of allylpolyfluoroarenes

Organozinc compounds of the general formula ArFZnX (X = Cl, ArF) were synthesized by reactions of Zn with chloropolyfluoroarenes and of Zn/SnCl2 with polyfluoroarenes. Polyflorinated organozinc compounds reacted with allyl chloride and allyl bromide to give the corresponding allyl-substituted polyfluoroarenes. The reactions with allyl chloride were carried out in the presence of copper(I) salts (CuCl or CuI).

Palladium-catalyzed synthesis of indene derivatives via propargylic carbonates with in situ generated organozinc compounds

The palladium-catalyzed carboannulation and arylation reaction of propargylic carbonates with in situ generated organozinc compounds produced an important new class of indene derivatives. The reaction proceeded under mild conditions, and indene products were isolated in good to excellent yields.

Reactions of Polyfluoroaromatic Organozinc Compounds with Acyl Chlorides and DMF

N,N-Dimethylbis(polyfluoroaryl)methanamines and polyfluoroarenes were obtained from polyfluoroaromatic organozinc compounds in DMF in the presence of acyl chlorides.