Palladium-catalyzed dehydrogenative cis double phosphorylation of alkynes with H-phosphonate leading to (Z)-bisphosphoryl-1-alkenes

Dehydrogenative cis double phosphorylation of terminal alkynes with H-phosphonate took place efficiently in the presence of a divalent palladium catalyst to afford (Z)-bisphosphoryl-1-alkenes selectively.     

A chemoselective reduction of alkynes to (E)-alkenes

The trans reduction of all types of alkynes to give (E)-olefins is achieved through a two-stage trans hydrosilylation and protodesilylation. Reaction of an alkyne and a silane with the ruthenium catalyst [Cp*Ru(MeCN)3]PF6 results in clean hydrosilylation to give only the (Z)-trans addition product at ambient temperature with catalyst loadings of 1-5 mol %. The crude vinylsilane products are then protodesilylated by the action of cuprous iodide and TBAF at rt-35 degrees C. The reaction is compatible with many sensitive functional groups and provides a general trans-alkyne reduction not possible by other means.     

Stereoselective hydrothiolation of alkynes catalyzed by cesium base: facile access to (Z)-1-alkenyl sulfides

Treatment of alkyne with alkanethiol in the presence of a catalytic amount of cesium carbonate and a radical inhibitor in DMSO provides the corresponding adduct, (Z)-1-alkenyl alkyl sulfide, in good yield with high selectivity.     

A tandem elimination-cyclization-Suzuki approach: efficient one-pot synthesis of functionalized (Z)-3-(arylmethylene)isoindolin-1-ones

A novel and efficient one-pot regioselective elimination-cyclization-Suzuki approach was developed to afford (Z)-3-arylmethyleneisoindolin-1-ones in good to excellent yields from easily accessible o-gem-dihalovinylbenzamides and organoboron reagents.     

Synthesis of internal alkynes via one-pot palladium-catalyzed and dehydrobromination reactions of 1,1-dibromo-1-alkenes

Tandem palladium-catalyzed cross-coupling of alkyl, alkenyl, alkynyl, aryl, and heteroaryl 2-substituted 1,1-dibromo-1-alkenes with aryl or heteroaryl boronic acids or borate esters and dehydrobromination of the intermediate coupled products afforded internal alkynes in moderate to good yields (up to 89%). The synthesis has been carried out in a one-pot process and in a two-step sequence according to the nature of the starting 1,1-dibromoalkenes. The reported protocol is compatible with the presence in the 1,1-dibromo-1-alkene molecule of additional reactive halogen–carbon bonds, thus allowing to build up more complex alkyne derivatives.     

Allylcyanation of alkynes: regio- and stereoselective access to functionalized di- or trisubstituted acrylonitriles

Allyl cyanides are found to add across alkynes in the presence of a nickel catalyst prepared from Ni(cod)2 and P(4-CF3-C6H4)3 in situ to give variously functionalized di- or trisubstituted acrylonitriles in highly stereoselective manners possibly via a pi-allylnickel species as an intermediate. alpha-Siloxyallyl cyanides also react at the gamma-position of a cyano group with both internal and terminal alkynes having various functional groups to give silyl enol ethers, which give the corresponding aldehydes or ketones upon hydrolysis.     

Novel 1,3-dipolar cycloaddition of diazocarbonyl compounds to alkynes catalyzed by InCl3 in water

The first intermolecular 1,3-dipolar cycloaddition of diazocarbonyl compounds with alkynes was developed by using an InCl(3) catalyzed cycloaddition in water. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-hydrogen (alkyl or aryl) migration.     

Alkynylzirconation of alkynes and application to one-pot bisalkynylation of alkynes

Stereocontrolled alkynylzirconation of unactivated alkynes was achieved by the reaction of an alkyne with Cp2ZrEt2 and alkynyl halide in this order. After hydrolysis of the alkynylzirconation product, trisubstituted enyne derivatives were obtained in good yields. Functionalized enynes were also prepared by the reaction of the alkynylzirconation products with a variety of electrophiles. Subsequent addition of the second alkynyl halide to the alkynylzirconation products provided an in situ protocol for bisalkynylation of alkynes into (Z)-enediynes in good yields.     

A novel one-pot four-component access to tetrahydro-beta-carbolines by a coupling-amination-aza-annulation-Pictet-Spengler sequence (CAAPS)

The four-component coupling-amination-aza-annulation-Pictet-Spengler (CAAPS) sequence of acid chlorides 1, terminal alkynes 2, tryptamine derivatives 6, and acryloyl chloride derivatives 4 represents a facile and rapid one-pot access to tetrahydro-beta-carbolines 7 in moderate to good yields.     

Highly (Z)-selective hydrosilylation of terminal alkynes catalyzed by a diphosphinidenecyclobutene-coordinated ruthenium complex: application to the synthesis of (Z,Z)-bis(2-bromoethenyl)arenes

[reaction: see text] Complex 1 bearing a diphosphinidenecyclobutene ligand (DPCB-OMe) catalyzes highly stereoselective hydrosilylation of diethynylarenes with HSiMe2Ph to afford (Z,Z)-bis(2-silylethenyl)arenes. Treatment of the hydrosilylation products with N-bromosuccinimide causes bromodesilylation in a stereospecific manner, giving (Z,Z)-bis(2-bromoethenyl)arenes in high geometrical purity (>98%).     

Domino reaction of arylaldehydes and 1-acetylcyclopropanecarboxamides: one-pot access to highly functionalized spiropiperidine-2,4-diones

A domino reaction based on arylaldehydes and 1-acetylcyclopropanecarboxamides has been developed, which allows one-pot and efficient synthesis of structurally complex piperidine-2,4-diones with multiple functionalities under mild conditions. The overall transformation involves tandem aldol/intramolecular aza-Michael/(aldol)/Michael sequences.     

A highly stereoselective, modular route to (E)-vinylsulfones and to (Z)- and (E)-alkenes

A recently discovered radical fragmentation of 2-fluoro-6-pyridinoxy derivatives allows a new highly stereoselective and convergent route to (E)-vinylsulfones from allylic alcohols. Reductive desulfonylation or nickel-catalyzed couplings furnish di- and trisubstituted (E)- and (Z)-alkenes.     

Use of InCl(3) as a cocatalyst and a Cl(2)Pd(DPEphos)-P(2-furyl)(3) catalyst system for one-pot hydrometalation-cross-coupling and carbometalation-cross-coupling tandem processes

One-pot conversion of alkynes to regio- and stereodefined alkenylmetals containing Al and Zr via hydrometalation or carbometalation followed by their Pd-catalyzed cross-coupling with (E)-ICH=CHBr or (E)-ICH=CHCl proceeds cleanly and selectively to give the corresponding 1-halo-1,3-dienes in excellent yields using a catalyst system consisting of Cl(2)Pd(DPEphos), DIBAL-H, and TFP (catalyst A) with InCl(3) as a cocatalyst.     

Stereoselective Synthesis of (Z)-1-Alkylseleno-1-alkenes by Ni-Catalyzed Coupling Reaction of (Z)-Dialkylselenoethenes with Organozinc Halides

Abstract

(Z)-Dialkylselenoethenes 2, prepared conveniently from the hydrozirconation of dialkylselenoacetylenes 1 with Cp₂Zr (H) Cl in THF followed by protonolysis, react readily at ? 10°C in THF with organozinc halides in the presence of a catalytic amount of NiCl₂ (dppe) to give (Z)-1-alkylseleno-1-alkenes 3 with retention of the configuration.     

Tandem catalysis and self-assembly: a one-pot approach to functionalized polymers

[reaction: see text] Side-chain functionalized polymers possessing terminal palladated SCS pincer complexes at each repeat unit were synthesized via ring-opening metathesis polymerization. These palladium centers function as both well-defined Heck catalysts and recognition units capable of quantitative self-assembly of pyridine-containing molecules. Exploitation of both the catalytic and self-assembly properties has led to the development of a controlled, one-pot tandem catalysis/self-assembly sequence for the synthesis of functionalized polymers.     

Base controlled (1,1)- and (1,2)-hydrophosphination of functionalized alkynes

The (1,1)- and (1,2)-addition of diphenylphosphine to 3-butyn-2-one and ethyl propiolate can be controlled chemoselectively by regulating the amount of triethylamine as the external base and in the presence of the chiral organopalladium(II) template derived from (R)-N,N-dimethyl-1-(1-naphthyl)ethylamine.     

A simple and effcient approach to one-pot synthesis of mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates catalyzed by InCl3简

An efficient and straightforward procedure has been developed for the synthesis of highly substituted mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via a one-pot, four-component domino reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of InCl3 （20 mol%） in MeOH at ambient temperature. The salient advantages of this method are mild reaction conditions, environmentally benign, high to excellent yields, shorter reaction times, easy operation and no column chromatographic separation.     

Regioselective synthesis of 1,3,5-substituted benzenes via the InCl(3)/2-iodophenol-catalyzed cyclotrimerization of alkynes

A novel indium(III)-catalyzed cyclotrimerization of alkynes in the presence of 2-iodophenol gave 1,3,5-substituted benzenes in excellent yields with complete regioselectivity. The reaction condition is tolerant to air, and atom economical, in accordance with the concept of modern green chemistry. This method provides a rapid and efficient access to 1,3,5-substituted benzenes.     

Stereoselective preparation of highly functionalized (Z)-3-magnesiated enoates by an iodine-magnesium exchange reaction

3-Iodoenoates are converted into the corresponding alkenylmagnesium species with complete retention of configuration of the double bond; both direct reaction and copper(I)-mediated reactions with various electrophiles provide polyfunctional enoates.     

General and selective synthesis of (Z)-3-haloacrylates via palladium-catalyzed carbonylation of terminal alkynes

A general and selective palladium-catalyzed carbonylation of terminal alkynes method for the synthesis of (Z)-3-haloacrylates is presented. In the presence of a catalytic amount of PdX2 and 5 equiv of CuX2 (X=Cl and Br), terminal alkynes were carbonylated to afford the corresponding (Z)-3-haloacrylates exclusively in moderate to good yields. The results showed that the effect of solvent had a fundamental influence on the chemoselectivity and stereoselectivity of the palladium-catalyzed carbonylation reaction.