Cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds catalyzed by a diphosphinidenecyclobutene-coordinated palladium complex

(π-Allyl)palladium triflate coordinated with 1,2-bis(4-methoxyphenyl)-3,4-bis(2,4,6-tri-t-butylphenylphosphinidene)cyclobutene (DPCB-OMe), [Pd(η³-C₃H₅)(DPCB-OMe)]OTf, efficiently catalyzes cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds such as acetylacetone and ethyl acetoacetate in toluene in the presence of pyridine. The reactions can be performed in air, giving 2-vinyl-2,3-dihydrofurans in good to high yields.     

Synthesis of triazoles from nonactivated terminal alkynes via the three-component coupling reaction using a Pd(0)-Cu(I) bimetallic catalyst

The synthesis of triazoles via the three-component coupling reaction of unactivated terminal alkynes, allyl carbonate, and trimethylsiyl azide under the Pd(0)-Cu(I) bimetallic catalyst is developed. The reaction most probably proceeds through the formation of a pi-allylpalladium azide complex and a copper-acetylide followed by a successive [3 + 2] cycloaddition. The deallylation of the resulting allyltriazoles proceeds very easily by the Ru-catalyzed isomerization followed by the ozonolysis of the resulting propenyltriazoles to give the triazoles in high 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%).     

A Convenient and Efficient Deallylation Procedure

In the Presence of NaBH4/BF3,allyl ethers underwent deallylation to the corresponding alcohols or phenols in good yield and high reaction rate.     

Insertion of CO2 into a palladium allyl bond and a Pd(II) catalysed carboxylation of allyl stannanes

The complex 2,6-bis[(di-t-butylphosphino)methyl]phenyl allyl palladium (PCP(tBu)Pd-allyl, 3) reacts with CO(2) in a very fast insertion reaction to give the corresponding butenoate complex. The reaction is thought to occur via a cyclic six-membered transition state (7), where the gamma-carbon of the allyl group is linked up with the CO(2)-carbon. A group of related PCP complexes were investigated as catalysts for the carboxylation of tributyl(allyl)stannane. A catalytic cycle is proposed for this reaction where the rate determining step is the transmetallation between tin and palladium. The carboxylation reaction is faster using less sterically crowded catalysts whereas the electron richness of the palladium complexes seems less important for reactivity. Thus, there was no apparent difference in reactivity between 2,6-bis[(di-phenylphosphino)methyl]phenyl palladium triflouroacetate (13) and resorcinolbis(diphenyl)phosphinite palladium triflouroacetate (10). Both of these complexes give high turnovers for the carboxylation of tributyl(allyl)stannane (80% in 16 h using a ca. 5% catalyst loading and 4 atm CO(2) pressure). On the other hand complex 3 was inactive in the catalytic carboxylation reaction.     

改进的1,3-缩水-2,4-二-氧-苄基-β-L-鼠李糖及1,3——缩水-2,4,6-三-氧-苄基-β-D-甘露糖的合成

用相应二丁基锡络合物对α-L-鼠李糖烯丙基苷及α-D-甘露糖烯丙基苷进行选择性3-氧-烯丙基化. 用(Ph~3P)~3RhCl催化脱烯丙基并苄基化得到相应的苄基化1,3-二醇. 再进行乙酰化,氯化,接着进行关环反应,得到1,3-缩水苄基内醚糖.     

Functionalization on silica gel with allylsilanes. A new method of covalent attachment of organic functional groups on silica gel

Treatment of an (allyl)organosilane with silica gel in refluxing toluene brought about deallylation forming an Si-O-Si bond with the silicon on the silica gel. This Si-O-Si bond formation provides us with a new reliable method for the functionalization of a silica gel surface.     

Design and synthesis of a chemically cleavable fluorescent nucleotide, 3'-O-allyl-dGTP-allyl-bodipy-FL-510, as a reversible terminator for DNA sequencing by synthesis

We report the construction of a novel chemically cleavable fluorescent labeling system based on an allyl group to modify nucleotide for DNA sequencing by synthesis (SBS). We have found that an allyl moiety can be used successfully as a linker to tether a fluorophore to a 3'-O-allyl-modified nucleotide, forming a chemically cleavable reversible terminator, 3'-O-allyl-dGTP-allyl-Bodipy-FL-510, for application in SBS. The fluorophore and the 3'-allyl group on a DNA extension product, which is generated by incorporating 3'-O-allyl-dGTP-allyl-Bodipy-FL-510, are removed simultaneously in 30 s by Pd-catalyzed deallylation in aqueous buffer solution. The resulting DNA product is successfully used as a primer for further extension in polymerase reaction. This one-pot dual-deallylation reaction thus allows the reinitiation of the polymerase reaction and increases the SBS efficiency.     

(Pi-allyl)palladium complexes bearing diphosphinidenecyclobutene ligands (DPCB): highly active catalysts for direct conversion of allylic alcohols

The (pi-allyl)palladium complex bearing an sp2-hybridized phosphorus ligand (DPCB-OMe: 1,2-bis(4-methoxyphenyl)-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene) efficiently catalyzes direct conversion of allylic alcohols in the absence of activating agents of alcohols such as Lewis acids. N-Allylation of aniline proceeds at room temperature to afford monoallylated anilines in 90-97% yields. C-Allylation of active methylene compounds is also successful at 50 degrees C using a catalytic amount of pyridine as a base, giving monoallylation products in 85-95% yields. The catalytic mechanism involving hydrido- and (pi-allyl)palladium intermediates has been proposed on the basis of stoichiometric examinations using model compounds of presumed intermediates.     

四氟乙烯齐聚体的反应 III: 四氟乙烯四聚体与脂族胺以及烷氧亲核试剂的反应

3, 4-Bis (trifluoromethyl)-perfluorohexene-(3) (1) reacted with diethylamine to give the 1-N, N-diethylamino-2-pentafluoroethyl -3-trifluoromethyl-perfluoropentene-(1)(2), which was easily hydrolyzed to the corresponding N, N-diethyl-2-penta-fluoroethyl- 3-trifluoromethyl-perfluoropenteno-(2)-amide (3). When compound 1 was allowed to react with n-butyl amine at 40-50`C, the 2,3,4-tris(trifluoromethyl)-4-pentafluoroethyl-1-n-butyl-aza- cyclobutene-(2) (5) was obtained as the main product and at-30-40`C, 3,4-bis(trifluoromethyl)-4-n-butylamino-perfluorohexene-(2) (4) as the main product. The isomers 3, 4-bis(trifluoromethyl)-4-allyloxy-perfluoro-hexen-(2) (6) and 2-pentafluoroethyl-3-trifluoromethyl-3-allyloxy-perfluoropentene-(1)(7) were formed when 1 was reacted with sodium allyl alcoholate.     

Catalytic deallylation of allyl- and diallylmalonates

Substituted allylmalonates undergo the selective C-C bond cleavage in the presence of triethylaluminum and a catalytic amount of nickel and ruthenium phosphine complexes, resulting in the loss of the allyl moiety and formation of monosubstituted malonates. Comparison of reactivity of the nickel and ruthenium complexes showed that the use of the former is general with respect to the structure of the substituted allylmalonates, and the activity of the latter depended on the substitution pattern of the double bond of the allylic moiety. The smooth deallylation may encourage the use of the allyl group as a protective group for the acidic hydrogen in malonates.     

Tandem isomerization/Claisen transformation of allyl homoallyl and diallyl ethers into gamma,delta-unsaturated aldehydes with a new three component catalyst Ru3(CO)12/imidazolinium salt/Cs2CO3

The three component catalyst Ru3(CO)12/1,3-bis(2,6-diisopropylphenyl)imidazolinium chloride/Cs2CO3 (molar ratio 1:3:6) successively promotes both allyl to vinyl isomerization and Claisen rearrangement from allyl homoallyl and diallyl ethers to selectively afford gamma,delta-unsaturated aldehydes.     

Chromatography-free Pd-catalyzed deprotection of allyl ethers using PS-DEAM as a scavenger of boronic acids and Pd catalyst

Polystyrene-bound diethanolamine (PS-DEAM) work-up for a newly developed Pd(PPh₃)₄-catalyzed cleavage of allylic alkyl ethers using phenylboronic acid can effectively release Pd-free parent alcohols. Furthermore, chromatography-free deallylation can be conducted by using vinylboronic anhydride pyridine complex as an allyl scavenger with a catalytic amount of Pd(OAc)₂ and 4-(diphenylphosphino)benzoic acid instead of Pd(PPh₃)₄ to yield the desired products in high purities and yields after removal of volatile byproducts and the phosphine-derived contaminants by evaporation and sequestration through acid-base interaction with PS-DEAM, respectively.     

Synthesis of allyl cyanamides and N-cyanoindoles via the palladium-catalyzed three-component coupling reaction

The palladium-catalyzed three-component coupling reaction (TCCR) of aryl isocyanides, allyl methyl carbonate, and trimethylsilyl azide was conducted in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and dppe (1,2-bis(diphenylphosphino)ethane) (10 mol %). Allyl aryl cyanamides with a wide variety of functional groups were obtained in excellent yields. This palladium-catalyzed TCCR was further utilized for the synthesis of N-cyanoindoles. The reaction of 2-alkynylisocyanobenzenes, allyl methyl carbonate, and trimethylsilyl azide in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and tri(2-furyl)phosphine (10 mol %) at higher temperatures afforded N-cyanoindoles in good to allowable yields. (eta(3)-Allyl)(eta(3)-cyanamido)palladium complex, an analogue of the bis-pi-allylpalladium complex, is a key intermediate in the TCCR, and a pi-allylpalladium mimic of the Curtius rearrangement is involved to generate the (eta(3)-allyl)(eta(3)-cyanamido)palladium intermediate.     

New fused dithiabicyclic compounds from the reaction of N,N-dialkyl perfluorothioamides with allylmagnesium halides

Allylmagnesium reagents react with N,N-dialkylperfluorothioamide to give, at low temperature, an adduct stable enough to be trapped. At room temperature, this adduct can evolve by elimination of either a sulfide salt, leading to an iminium intermediate, and then an N,N-dialkyl-α,α-bis(allyl)-α-perfluoroalkylamine. This process is favoured if an excess of allyl magnesium is used. Alternatively, the adduct eliminates an aminyl moiety giving allyl(perfluoroalkyl)thioketone which is converted in situ into an unprecedented fused bis(perfluoroalkyl) bis(dihydrothiopyrane). A sequence deprotonation of the thioketone - oxidation of the resulting dienethiolate - dimerization of the dienethiyl radical is proposed to rationalize the formation of this unexpected bicyclic compound.     

Synthesis of oxazoles through Pd-catalyzed cycloisomerization-allylation of N-propargylamides with allyl carbonates

In the presence of Pd₂(dba)₃-Cy₃P catalyst, IPr·HCl salt [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], and Cs₂CO₃, N-propargylamides react with allyl carbonates to give 2,5-disubstituted oxazoles having homoallyl groups through the tandem cycloisomerization-allylation.     

Ruthenium-catalyzed intramolecular oxidative amination of aminoalkenes enables rapid synthesis of cyclic imines.

[RuCl2(CO)3]2/dppp is shown to be a highly effective catalyst system for the first intramolecular oxidative amination of a variety of aminoalkenes when it is used concomitantly with K2CO3 and allyl acetate in N-methylpiperidine, to give the corresponding cyclic imines and indoles in excellent yields. For example, the reaction of 2,2-diphenyl-4-pentenyl-1-amine performed in the presence of 2 mol % of [RuCl2(CO)3]2, 4 mol % of dppp, K2CO3, and allyl acetate in N-methylpiperidine at 140 degrees C for 8 h gives 4,4-diphenyl-2-methyl-1-pyrroline in quantitative (>99%) yield.     

四氟乙烯齐聚体的反应: II.四氟乙烯五聚体和烯丙醇的反应及反应产物的转化

The reaction of perfluoro- (3, 4-dimethyl-3-ethylhexene-(2)) (1) with allyl alcohol under different conditions gave different products. Compound 1 reacted with sodium allyl alcoholate yielding 2-(1'-allyloxy-tetrafluoroethyl)-perfluoro(3-methyl-3-ethylpentene- (1))(2). In the presence of triethylamine, 1 reacted with allyl alcohol to give 2-allyloxy-perfluoro (3, 4-dimethy1-4-ethylhexene- (2))(3), and in the presence of acetone and K2CO3 to give compound 4. These reactions all gave allyl-3-trifluoromethyl-3- pentafluoroethyl-2,2-dihydro-pentafluorovalerate (5a) as byproduct. Compound 1 reacted with allyl alcohol in the presence of triethylamine at 20-22`C to give 2, at 30-35`C to give a mixture of 2 and 3 and at 35-40`C to give a mixture of 3 and 5a respectively. Compound 2 was transformed to compound 4 in acetone and in the psesence of K2CO3, \o\ compound 5a or 5b in the corresponding alcohol and to compound 6 on reacting with dimethylamine. Compound 2 as well as 3 was converted to perfluoro-(3-ethyl-2,3,4,5- tetramethyl-2,3-dihydrofuran) (7) by KF in sulpholane.     

Facile deallylation protocols for the preparation of N-unsubstituted triazoles and tetrazoles

Two facile deallylation protocols have been developed for the preparation of N-unsubstituted triazoles and tetrazoles. The first protocol is a direct deallylation using a combination of a catalytic amount of nickel complex, NiCl2(dppe), and a stoichiometric amount of Grignard reagent, tBuMgCl. The second protocol is a stepwise deallylation through consecutive reactions of isomerization and ozonolysis. The isomerization from N-allylazoles to N-vinylazoles is catalyzed by a ruthenium complex, HRuCl(CO)(PPh3)3, and the following ozonolysis of the derived N-vinyl intermediates affords N-unsubstituted azoles. These protocols can be used complementarily depending on the type of functional groups in the parent allylated azoles.     

Selective mono- and di-allylation and allenylation of chlorosilanes using indium

Allyl and allenyl groups have been introduced into silicon systems by the allylation and allenylation of chlorosilanes using allyl bromide or propargyl bromide with indium. The allylation of chlorosilanes afforded a variety of aryl, aralkyl, and alkenyl substituted allylsilanes. By applying this method, the reactions of 1-bromo-3-methylbut-2-ene, 3-bromo-2-methylprop-1-ene and 3-bromobut-1-ene with chlorosilanes also proceed smoothly to give regioselectively allylic rearrangement products in good yields. Mediated by indium, dichlorosilanes (R₂SiCl₂) and trichlorosilanes (RSiCl₃) can either afford monoallylated silanes or diallylated silanes depending on the amount of allyl bromide and indium used.