Nickel(0)-Catalyzed Three-Component Connection Reaction of Dimethylzinc, 1,3-Dienes, and Carbonyl Compounds

Linear 1:1:1 coupling of dimethylzinc, 1,3-dienes, and carbonyl compounds in this order is facilitated by catalytic amounts of [Ni(acac)(2)] to give (E)-3-hexen-1-ols in good yields under mild conditions [Eq. (a)]. Increasing steric hindrance at the carbonyl group favors formation of the 1:2:1 adduct, and this is the sole product when the carbonyl compound is acetone. acac=acetylacetonate.     

Novel Catalytic CO(2) Incorporation Reaction: Nickel-Catalyzed Regio- and Stereoselective Ring-Closing Carboxylation of Bis-1,3-dienes

Novel nickel-catalyzed carboxylation of bis-1,3-dienes using carbon dioxide (CO2) was investigated. In the presence of catalytic amounts of Ni(acac)2 and PPh3, various bis-1,3-dienes smoothly reacted with CO2 and an organozinc reagent (Et2Zn, Me2Zn, or Ph2Zn) under mild conditions. This catalytic carboxylation process was accompanied by carbocyclization of bis-1,3-diene followed by alkylation by an organozinc reagent to afford cyclic carboxylic acid derivatives in high yields with high regio- and stereoselectivities.     

Construction of fused, bridged, and spiro bicyclic skeletons via nickel-catalyzed intramolecular cyclization of cyclic 1,3-dienes and a tethered aldehyde

Nickel-catalyzed intramolecular cyclization of cyclohexa-1,3-dienes and an aldehyde in a chain produced fused, bridged or spiro bicyclic skeletons depending on the length of the tether. This chemistry can be extended to cyclohepta-1,3-dienes and cyclohepta-1,3,5-trienes having an aldehyde moiety on the side chain.     

Hinged bis-porphyrin scaffolds I. The synthesis of a new porphyrin diene and its role in constructing hinged porphyrin dyads and cavity systems

Norbornene building BLOCKs formed by the reaction of porphyrin 1,3-dienes with norbornadiene or dimethyl tricyclo[4.2.1.0^2,5]nona-2,7-diene-3,4-dicarboxylate were coupled with an ester-activated cyclobutene epoxide BLOCK to afford the first examples of hinged porphyrin-spacer-acceptor dyads. Similar dual coupling with a bis-(cyclobutene epoxide) formed doubly hinged POR-spacer-POR scaffolds separated by up to 16σ-bonds. The ability of the doubly hinged ZnPOR-16σ-ZnPOR scaffold to adopt cavity-shaped conformations was indicated by semiempirical AM1 calculations of these conformationally flexible bis-porphyrin scaffolds.     

Nickel(0)-catalyzed asymmetric hydrocyanation of 1,3-dienes

1,2-Bis-diarylphosphinites are excellent ligands for the Ni(0)-catalyzed hydrocyanation of certain types of 1,3-dienes. 1-Phenyl-1,3-butadiene, 1-vinyl-3,4-dihydronaphthalene, and 1-vinylindene undergo highly regioselective hydrocyanation under ambient conditions to give exclusively the 1,2-adducts in good to excellent yields. Using bis-1,2-diarylphosphinites derived from d-glucose, the highest enantioselectivities to-date for asymmetric hydrocyanation of 1,3-dienes (70-83% ee's) have been obtained.     

Simple preparation of diamondoid 1,3-dienes via oxetane ring opening

The transformations of apical mono- and bisacetyl diamondoids to the respective oxetanes and subsequent acid-catalyzed ring opening/dehydration lead to diamondoidyl mono- and bis-1,3-dienes in high preparative yields.     

Cross-metathesis of 1,3-dienes with electron-deficient olefins

Cross-metathesis reactions between 1,3-dienes and electron-deficient olefins have been investigated. Terminal monosubstituted 1,3-dienes afforded low yields of the desired CM products due to competing cleavage of the internal double bond. This undesired cleavage is successfully suppressed in the case of 1,3-dienes containing a sterically more congested internal double bond. Methyl vinyl ketone as the coupling partner was shown to provide the best yields.     

Julia-Kocienski reaction-based 1,3-diene synthesis: aldehyde-dependent (E,E/E,Z)-selectivity

A new modification of Julia-Kocienski olefination reaction based on the use of cation-specific chelating agents that yields 1,3-dienes with predictable (E/Z)-selectivity on newly created double bond was developed. The influence of the aldehyde structure on reaction (E/Z) selectivity is discussed and rationalized.     

Nickel-catalyzed enantio- and diastereoselective three-component coupling of 1,3-dienes, aldehydes, and silanes using chiral N-heterocyclic carbenes as ligands

Nickel(0)-catalyzed asymmetric three-component coupling of 1,3-dienes, aldehydes, and silanes has been realized utilizing a chiral N-heterocyclic carbene as a ligand. On the basis of the screening of various NHC precursors, an imidazolium salt having 1-(2,4,6-trimethylphenyl)propyl groups on the nitrogen was designed and synthesized. In this reaction, various coupling products were produced in good yields with high regio-, diastereo- (anti selective in the case of the internal 1,3-diene), and enantioselectivities (up to 97% ee).     

Synthesis of highly substituted 1,3-dienes, 1,3,5-trienes, and 3,6-disubstituted cyclohexenes by the palladium-catalyzed coupling of organic halides, internal alkynes or 1,3-cyclohexadienes, and organoboranes

A number of highly substituted 1,3-dienes and 1,3,5-trienes have been stereoselectively prepared in moderate to good yields by the coupling of vinylic iodides, internal alkynes, and organoboranes in the presence of a palladium catalyst. Optimal reaction conditions for different organoboron substrates have been developed. The analogous three-component coupling of aryl halides, 1,3-cyclohexadiene, and boronic acids provides a synthetically useful route to 3,6-disubstituted cyclohexenes. These methods are very efficient and provide an expeditious way to synthesize the indicated alkenes, dienes, and trienes, whose preparation would normally require multi-step synthesis.     

Nickel-catalyzed intermolecular coupling of 1,3-dienes and aldehydes via transmetalation of nickelacycles with diisobutylaluminum acetylacetonate

Intermolecular coupling reactions of 1,3-dienes and aldehydes via transmetalation of nickelacycle intermediate with (i)Bu(2)Al-acac were investigated. In the reactions, a linear adduct or a branched adduct was produced, depending upon the nature of 1,3-dienes and aldehydes, via two nickelacycles that were relatively stable among the four possible nickelacycles because of the equilibrium with pi-allynickel forms.     

金属钐作用下α,α'-二溴代烷基酮与1,3-二烯的[3+4]环加成反应

α,α'-二溴代万花筒特 环状共轭二烯烃(环戊二烯,呋喃) 在金属钐粉和磺化亚铜(10%)作用下, 高产率地得到[3+4]环加成产物. 与开链共轭二烯烃作用没能得到环加成产物. 却高产率地得到α,α'-二溴代烷基酮自身偶合产物环戊烯酮衍生物 .     

Efficient one-to-one coupling of easily available 1,3-dienes with carbon dioxide

An efficient one-to-one coupling reaction of atmospheric pressure carbon dioxide with 1,3-dienes is realized for the first time through PSiP-pincer type palladium-catalyzed hydrocarboxylation. The reaction is applicable to various 1,3-dienes including easily available chemical feedstock such as 1,3-butadiene and isoprene. This protocol affords a highly useful method for the synthesis of β,γ-unsaturated carboxylic acid derivatives from CO(2).     

Divergent regioselective synthesis of 2,5,6,7-tetrahydro-1H-1,4-diazepin-2-ones and 5H-1,4-benzodiazepines

A novel and simple one-pot synthesis of 3-substituted 2,5,6,7-tetrahydro-1H-1,4-diazepin-2-ones from 1,2-diaza-1,3-dienes (DDs) and N-unsubstituted aliphatic 1,3-diamines is described. Here we also report a procedure to selectively obtain alkyl 5H-1,4-benzodiazepine-3-carboxylates from the DDs and 2-aminobenzylamine. Both processes occur by means of sequential 1,4-conjugated addition followed by regioselective 7-exo cyclization. The behavior of N-methyl- and N,N'-dimethyl-1,3-diaminopropanes toward the DDs furnished pyrazol-3-ones and bis-α-aminohydrazones, respectively.     

Studies on highly stereoselective addition-elimination reactions of 3-(methoxycarbonyl)-1,2-allen-4-ols with MX. An efficient synthesis of 3-(methoxycarbonyl)-2-halo-1,3(Z)-dienes

3-(Methoxycarbonyl)-2-halo-1,3(Z)-dienes were prepared highly stereoselectively via SN2'-type addition-elimination reactions of 3-(methoxycarbonyl)-1,2-allen-4-ols with MX. These products may easily undergo Negishi or Sonogashira coupling reactions to yield a series of stereodefined polysubstituted (E)-1,3-dienes.     

Synthesis of highly substituted 1,3-dienes and 1,3,5-trienes by the palladium-catalyzed coupling of vinylic halides,internal alkynes,and organoboranes

[reaction: see text] Highly substituted 1,3-dienes and trienes have been prepared in good to excellent yields by the palladium-catalyzed coupling of vinylic halides, internal alkynes, and organoboranes.     

Highly regioselective, catalytic asymmetric reductive coupling of 1,3-enynes and ketones

[reaction: see text] Highly regioselective, catalytic asymmetric reductive coupling reactions of 1,3-enynes and ketones have been achieved using catalytic amounts of Ni(cod)(2) and a P-chiral, monodentate ferrocenyl phosphine ligand. These couplings represent the first examples of catalytic, intermolecular reductive coupling of alkynes and ketones, enantioselective or otherwise, and afford synthetically useful 1,3-dienes possessing a quaternary carbinol stereogenic center in up to 70% ee.     

Highly enantioselective catalytic carbon dioxide incorporation reaction: nickel-catalyzed asymmetric carboxylative cyclization of bis-1,3-dienes

A method for nickel-catalyzed asymmetric carbon dioxide (CO2) incorporation via carbon-carbon bond formation was developed. In the presence of a catalytic amount of Ni(acac)2 and MeO-MOP, various bis-1,3-dienes reacted with CO2 (1 atm) and a diorganozinc reagent (Me2Zn or Ph2Zn) to afford cyclic carboxylic acids in good yields (71-100%) and with high enantioselectivities (90-96% ee).     

Palladium-catalyzed synthesis of 3-trifluoromethylated 1,3-dienes from acrylate derivatives and BTP

Here we reported a Pd-catalyzed coupling reaction between acrylate derivatives and BTP (2-bromo-3,3,3-trifluoropropene) to access 3-trifluoromethylated 1,3-dienes. The reaction allows the formation of the corresponding products in good to excellent yields and moderate Z/E diastereoisomeric ratios. This method broadens the current toolbox to access 3-trifluoromethylated 1,3-dienes.     

Domino N-H/C-H bond activation: copper-catalyzed synthesis of nitrogen-bridgehead heterocycles using azoles and 1,4-dihalo-1,3-dienes

Copper-catalyzed tandem coupling of 1,4-dihalo-1,3-dienes with azoles via an N-H bond and its adjacent C-H bond activation has been described. The reaction exhibits good regioselectivity when unsymmetrical 1,4-dihalo-1,3-diene is employed. This method provided a novel route to the synthesis of nitrogen-bridgehead azolopyridine derivatives.