- Synthesis of highly decorated chiral 2-nitro-cyclohexane carboxylic esters through microwave-assisted organocatalyzed cascade reactions
-
Starting from (E)-β-substituted-β-nitroacrylates and α,β-unsaturated ketones, a stereoselective organocatalyzed one-pot methodology allowed to synthesize highly decorated chiral 2-nitro-cyclohexane carboxylic esters. The reaction is promoted by Cinchona a
- Massolo, Elisabetta,Benaglia, Maurizio,Parravicini, Davide,Brenna, Davide,Annunziata, Rita
-
-
Read Online
- Conjugate allylation to α,β-unsaturated aldehydes with the new chemzyme p-F-ATPH
-
Success at last: The 1,4-allylation of α,β-unsaturated aldehydes with selectivities up to 95/5 and yields of 83% has been achieved thanks to the newly developed Lewis acidic receptor p-F-ATPH (L= 2,6-(p-FC6H4)2C6H3O). In addition to a coordination site for the aldehyde, this possesses an appropriate coordination site for a reactive nucleophile, as shown schematically on the right.
- Ooi,Kondo,Maruoka
-
-
Read Online
- Alkylation of unsaturated aldehyde and allylic bisacetate with organomanganese reagents in presence of tetrakis acetonitrile copper(I) tetrafluroborate
-
The conjugate addition of organomanganese reagents to α,β- unsaturated aldehydes and allylic bisacetate in presence of Me3Si-Cl and tetrakis acetonitrile copper(I) tetrafluroborate is described. Copyright Taylor & Francis, Inc.
- Deshmukh,Jadhav,Mali,Suryawanshi,Anbhule,Jagtap,Deshmukh
-
-
Read Online
- Evaluation of several fluorinated ATPH derivatives as functionalized Lewis acid receptors for conjugate alkylation to α,β-unsaturated aldehydes with alkyllithium nucleophiles
-
Several fluorinated aluminum tris(2,6-diphenylphenoxide) (ATPH) derivatives have been synthesized to evaluate, as functionalized Lewis acid receptors, the conjugate alkylation ability to α,β-unsaturated aldehydes by the combined use of alkyllithium nucleo
- Ooi, Takashi,Kondo, Yuichiro,Miura, Tomoya,Maruoka, Keiji
-
-
Read Online
- Accessing Both Retention and Inversion Pathways in Stereospecific, Nickel-Catalyzed Miyaura Borylations of Allylic Pivalates
-
We have developed a stereospecific, nickel-catalyzed Miyaura borylation of allylic pivalates, which delivers highly enantioenriched α-stereogenic γ-aryl allylboronates with good yields and regioselectivities. Our complementary sets of conditions enable access to either enantiomer of allylboronate product from a single enantiomer of readily prepared allylic pivalate substrate. Excellent functional group tolerance, yields, regioselectivities, and stereochemical fidelities are observed. The stereochemical switch from stereoretention to stereoinversion largely depends upon solvent and can be explained by competitive pathways for the oxidative addition step. Our mechanistic investigations support a stereoretentive pathway stemming from a directed oxidative addition and a stereoinvertive pathway that is dominant when MeCN blocks coordination of the directing group by binding the nickel catalyst.
- Zhou, Qi,Srinivas, Harathi D.,Zhang, Songnan,Watson, Mary P.
-
supporting information
p. 11989 - 11995
(2016/10/07)
-
- Catalytic asymmetric addition of aldehydes using organolithium reagents in the presence of commercial available chiral diol ligands
-
An efficient method for the catalytic asymmetric additions to aldehydes using organolithium reagents and titanium(IV) isopropoxide in the presence of commercially available and relatively inexpensive diol ligands, such as (S)-BINOL or D-TADDOL has been developed. Good to excellent yields (up to 92%) and enantioselectivities (up to 94%) of the corresponding secondary alcohol products can be obtained following a simple procedure at relatively mild reaction temperatures.
- Zong, Hua,Huang, Huayin,Song, Ling
-
supporting information
p. 1069 - 1074
(2016/10/11)
-
- Pincer-Nickel-Catalyzed Allyl-Aryl Coupling between Allyl Methyl Ethers and Arylzinc Chlorides
-
The P,N,N-pincer nickel complex [Ni(Cl){N(2-Ph2PC6H4)(2′-Me2NC6H4)}]-catalyzed allyl-aryl coupling was studied. The reaction of allyl methyl ethers, including (1-methoxyallyl)arenes and (3-methoxyprop-1-en-1-yl)arenes, with arylzinc chlorides afforded linear (E)-alkenes in high yields, whereas the reaction of (E)-1-methoxytridec-2-ene with p-Me2NC6H4ZnCl generated a mixture of linear and branched alkenes.
- Tao, Jian-Long,Yang, Bo,Wang, Zhong-Xia
-
p. 12627 - 12634
(2016/01/09)
-
- 1,n-rearrangement of allylic alcohols promoted by hot water: Application to the synthesis of navenone B, a polyene natural product
-
It was reported for the first time that hot water as a mildly acidic catalyst efficiently promoted 1,n-rearrangement (n = 3, 5, 7, 9) of allylic alcohols. In some cases, the rearrangement reactions joined isolated C-C double or triple bonds to generate conjugated polyene or enyne structure motifs. We used the 1,3-rearrangement reaction of an allylic alcohol in hot water as part of an attractive new strategy for construction of the polyene natural product navenone B by iterative use of a Grignard reaction, a 1,3-rearrangement of the resulting allylic alcohol, and subsequent oxidation of the rearranged product.
- Li, Pei-Fang,Wang, Heng-Lu,Qu, Jin
-
p. 3955 - 3962
(2014/05/20)
-
- Pd-Catalyzed stereospecific allyl-aryl coupling of allylic alcohols with arylboronic acids
-
An efficient method for Pd-catalyzed stereospecific allyl-aryl coupling of allylic alcohols with arylboronic acids has been described. The reactions proceeded smoothly in the presence of Pd2(dba)3· CHCl3 and racemic BINAP
- Ye, Jiang,Zhao, Jingming,Xu, Jing,Mao, Yuxue,Zhang, Yong Jian
-
supporting information
p. 9761 - 9763
(2013/10/21)
-
- Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)-h 8-binol
-
Three alkyltitanium reagents of RTi(O-i-Pr)3 (R = Cy (1a), i-Bu (1b), and n-Bu (1c)) were prepared in good yields. The high-resolution mass spectroscopy showed that 1b and 1c in the gas phase are monomeric species. However, the solid state of 1a revealed a dimeric structure. Asymmetric additions of 1a-1c to aldehydes catalyzed by a titanium catalyst of (R)-H 8-BINOL were studied at room temperature. The reactions produced desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 94% ee. Reactivity and enantioselectivity differences, in terms of steric bulkiness of the R nucleophiles, are herein described. The addition reactions of secondary c-hexyl to aldehydes were slower than the reactions of primary i-butyl or n-butyl nucleophiles. For the primary alkyls, lower enantioselectivities were obtained for products from addition reactions of the linear n-butyl as compared with the enantioselectivities of products from the addition reactions of the branched i-butyl group. The same stereochemistry of RTi(O-i-Pr)3 addition reactions as the addition reactions of organozinc, organoaluminum, Grignard, or organolithium reagents directly supports the argument of that titanium-catalyzed addition reactions of aldehydes involve an addition of an organotitanium nucleophile.
- Li, Qinghan,Gau, Han-Mou
-
experimental part
p. 929 - 939
(2012/06/29)
-
- Structure-based optimization of click-based histone deacetylase inhibitors
-
Previously, we reported a click-chemistry based approach to the synthesis of a novel class of histone deacetylase (HDAC) inhibitors [1]. The lead compound NSC746457 was found to be as potent as SAHA (Vorinostat). Further optimization of NSC746457 by using
- Hou, Jingli,Feng, Congran,Li, Zhonghua,Fang, Qinghong,Wang, Huihui,Gu, Guoxian,Shi, Yikang,Liu, Pi,Xu, Feng,Yin, Zheng,Shen, Jie,Wang, Peng
-
supporting information; experimental part
p. 3190 - 3200
(2011/07/29)
-
- Palladium-catalyzed γ-selective and stereospecific allyl-aryl coupling between acyclic allylic esters and arylboronic acids
-
Reactions between acyclic (E)-allylic acetates and arylboronic acids in the presence of a palladium catalyst prepared from Pd(OAc)2, phenanthroline (or bipyridine), and AgSbF6 (1:1.2:1) proceeded with excellent γ-selectivity to afford allyl-aryl coupling products with E-configuration. The reactions of α-chiral allylic acetates took place with excellent α-to-γ chirality transfer with syn stereochemistry to give allylated arenes with a stereogenic center at the benzylic position. The reaction tolerated a broad range of functional groups in both the allylic acetates and the arylboronic acids. Furthermore, γ-arylation of cinnamyl alcohol derivatives afforded gem-diarylalkane derivatives containing an unconjugated alkenic substituent. The synthetic utility of this method was demonstrated by its utilization in an efficient synthesis of (+)-sertraline, an antidepressant agent. The observed γ-regioselectivity and E-1,3-syn stereochemistry were rationalized based on a Pd(II) mechanism involving transmetalation between a cationic mono(acyloxo)palladium(II) complex and arylboronic acid, and directed carbopalladation followed by syn-β-acyloxy elimination. The results of stoichiometric reactions of palladium complexes related to possible intermediates were fully consistent with the proposed mechanism.
- Ohmiya, Hirohisa,Makida, Yusuke,Li, Dong,Tanabe, Masahito,Sawamura, Masaya
-
supporting information; experimental part
p. 879 - 889
(2010/03/25)
-
- Enantioselective addition of alkenylzinc reagents to aldehydes with organoboronates as the alkenyl source
-
Alkenylboronates were used as a vinyl source in the asymmetric addition of an alkenylzinc reagent to aldehydes catalyzed by a dendritic ligand. The resulting allylic alcohol products were obtained in 66-96% ee and 35-64% yields.
- Chai, Zhuo,Liu, Xin-Yuan,Zhang, Jun-Kang,Zhao, Gang
-
p. 724 - 728
(2008/02/01)
-
- Asymmetric sulfur ylide reactions with boranes: Scope and limitations, mechanism and understanding
-
The reactions of aryl-stabilized sulfur ylides with organoboranes has been studied under a variety of conditions. At 5 or -78°C, the reaction with Et3B gave a mixture of the first and second homologation products, but at -100°C, only the first homologation product was obtained even with just 1.1 equiv of Et3B. Under these optimized conditions, the chiral sulfur ylides (derived from camphor sulfonic acid) with different aryl groups were reacted with Et3B to give the corresponding alcohols (95-98% yield, 96-98% ee) and amines (74-77% yield, >98% ee). The origin of the high enantioselectivity is discussed. The use of nonsymmetrical 9-BBN derivatives was also explored. It was found that whereas primary alkyl substituents gave mixtures of products derived from competing migration of the boron substituent and the boracycle, all other groups resulted in either exclusive migration of the boron substituent (Ph, hexenyl, i-Pr) or exclusive migration of the boracycle (hexynyl, cyclopropyl). The factors responsible for the outcome of the reactions involving a hindered (i-Pr) and an unhindered (propynyl) substituent were studied by DFT calculations. This revealed that, in the case of an unhindered substituent, the conformation of the ate complex is the dominant factor whereas, in the case of a hindered substituent, the barriers to interconversion between the conformers of the ate complex and subsequent migration control the outcome of the reaction.
- Fang, Guang Y.,Wallner, Olov A.,Di Blasio, Nadia,Ginesta, Xavier,Harvey, Jeremy N.,Aggarwal, Varinder K.
-
p. 14632 - 14639
(2008/09/17)
-
- Strategies for expanding structural diversity available from olefin isomerization-Claisen rearrangement reactions
-
Boron-substituted di(allyl) ethers provide an efficient conduit for expanding the structural diversity available from olefin isomerization-Claisen rearrangement (ICR) reactions. Easily prepared allyl propargyl ethers undergo chemoselective Zr(IV)-catalyze
- Stevens, Benjamin D.,Bungard, Christopher J.,Nelson, Scott G.
-
p. 6397 - 6402
(2007/10/03)
-
- A positional scanning approach to the discovery of dipeptide-based catalysts for the enantioselective addition of vinylzinc reagents to aldehydes
-
A combinatorial library of dipeptide N-acylethylenediamine-based ligands was synthesized by parallel solid-phase methods. These ligands were screened in crude form as catalysts for the asymmetric addition of vinylzinc reagents to aldehydes to give chiral allylic alcohols. Three sites of diversity on the ligands were optimized using a positional scanning approach. The optimized structure from the library, ligand 54, was found to catalyze the formation of 10 different (E)-allylic alcohols with enantioselectivities ranging from 90% to 95% ee. This ligand was effective for both aromatic and α-branched aldehydes, and vinylzinc reagents derived from both bulky and straight chain terminal alkynes.
- Sprout, Christopher M.,Richmond, Meaghan L.,Seto, Christopher T.
-
p. 7408 - 7417
(2007/10/03)
-
- Tandem addition β-lithiation - Alkylation sequence on α,β-unsaturated aldehydes
-
A tandem reaction between (E)-cinnamaldehyde, 1a, and phenyllithium affording β-substituted dihydrochalcones was recently reported. NMR spectroscopic studies on the reaction mixture, as well as isotopic exchange reactions and trapping of two intermediates, provide clues on the several mechanistic steps of this new reaction. Extended studies revealed that β-alkyl-substituted α,β-unsaturated aldehydes and aliphatic lithium reagents did not afford good yields of the tandem reaction products, while aromatic lithium reagents gave good results. The aggregation features of the aryllithium reagents and the extended charged delocalization effects are considered to promote β-selectivity. This approach provides a convenient route for the synthesis of a wide variety of β-alkyl-substituted dihydrochalcones.
- Nudelman,Garcia
-
p. 1387 - 1394
(2007/10/03)
-
- A novel tandem Michael addition/Meerwein-Ponndorf-Verley reduction: Asymmetric reduction of acyclic α,β-unsaturated ketones using a chiral mercapto alcohol
-
The introduction of a thiol group into a chiral alcohol reagent for asymmetric Meerwein-Ponndorf-Verley (MPV) reductions allows asymmetric reduction of α,β-unsaturated ketones to secondary alcohols and allylic alcohols via a novel tandem Michael addition/MPV reduction. The reaction of acyclic α,β-unsaturated ketones 1 and an optically active 1,3-mercapto alcohol (-)-2 using dimethylaluminum chloride afforded the MPV reduction products 3 diastereoselectively in very high yields (up to 96%). Mechanistic studies elucidated (1) the structure of the chelation complex D with (-)-2 and Me2AlCl, (2) an asymmetric 1,7-hydride shift (intramolecular MPV reduction), and (3) dynamic kinetic resolution via reversible Michael addition. Subsequent reductive desulfurization of the MPV products 3 with a modified Raney nickel system led to the highly enantioselective reduction of α,β-unsaturated ketones to saturated secondary alcohols in 96-98% ee. β-Elimination of the corresponding sulfoxides gave the allylic alcohols in 86-98% ee. Applications to the asymmetric reduction of a synthetic intermediate 1m of prostaglandins and to a new asymmetric synthesis of the (+)-Rove beetle pheromone 11 are described.
- Node, Manabu,Nishide, Kiyoharu,Shigeta, Yukihiro,Shiraki, Hiroaki,Obata, Kenichi
-
p. 1927 - 1936
(2007/10/03)
-
- The copper mediated Barbier reactions of α,β-unsaturated ketones: Regioselective conjugate and 1,2-addition
-
The one-pot reaction of isophorone and other α,β-unsaturated ketones with alkyl and aryl halides in the presence of magnesium and a copper salt ('Barbier' conditions) leads to the regiospecific formation of 1,4-addition products; the use of lithium leads to regioselective 1,2-addition.
- Costello, Declan P.,Geraghty, Niall W. A.
-
p. 3083 - 3096
(2007/10/03)
-
- Tetraorganogallate complexes in organic chemistry: Michael addition to α, β-unsaturated compounds
-
Tetraorganogallate complexes, prepared in situ by addition of an organolithium reagent to a triorganogallium, reacted smoothly with α,β- unsaturated compounds to give Michael addition products in high yields, and mixed gallates display very high chemoselectivity in the transfer of one of their ligands.
- Han, Ying,Huang, Yao-Zeng,Fang, Lei,Tao, Wen-Tian
-
p. 867 - 876
(2007/10/03)
-
- The regioselective 1,4-addition reaction of alkenylboronic acids to α,β,α′,β′-unsaturated ketones
-
The effect of substituents on the double bond of α,β-unsaturated ketones for the 1,4-addition reaction rate of alkenylboronic acids induced by cyanuric fluoride was studied in detail. When the steric hindrance around the β-carbon of the unsaturated ketones increased, the 1,4-addition reaction rate significantly decreased. An alkyl substituent on the α-carbon was also found to significantly affect the 1,4-addition reaction. From these results, unsymmetric α,β,α′,β′unsaturated ketones (10a-f) were designed for the regioselective 1,4-addition reaction with alkenylboronic acids (4a-j). Since they have substituents to disturb the 1,4-addition reaction on only one double bond, the alkenylboronic acids reacted with them from only one side to selectively provide γ,δ,α′,β′-unsaturated ketones (11a-q). Further transformations of the resulting γ,δ,α′,β′-unsaturated ketones were also performed.
- Hara, Shoji,Shudoh, Hisashi,Ishimura, Shigeyuki,Suzuki, Akira
-
p. 2403 - 2408
(2007/10/03)
-
- Enantioselective addition of tris(TADDOL) organocerium reagents to aldehydes
-
A significant improvement in enantioselectivity (up to 92% ee) was achieved in butyl additions to a range of aldehydes with a novel tris(TADDOL) organocerium reagent.
- Greeves, Nicholas,Pease, J. Elizabeth
-
p. 5821 - 5824
(2007/10/03)
-
- Baker's Yeast-mediated Transformations of α-Keto Epoxides
-
αβ-Epoxy ketones on treatment with baker's yeast yield different types of products depending on their substitution.Small groups such as H or Me attached at the epoxy end protect that end from attack.Thus,1-acyl epoxides with H, methyl or propyl as the 2-e
- Meth-Cohn, Otto,Horak, R. Martinus,Fouche, Gerda
-
p. 1517 - 1528
(2007/10/02)
-
- Chemoselectivity in the ruthenium-catalyzed redox isomerization of allyl alcohols
-
Adjustment of oxidation level by internal hydrogen reorganization represents a highly efficient synthetic protocol. Cyclopentadienylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate catalyzes the redox isomerization of allyl alcohols to their saturated aldehydes or ketones. High chemoselectivity is observed since simple primary and secondary alcohols and isolated double bonds are not affected by this catalyst. The reaction is sensitive to the degree of substitution on the double bond and requires relatively unhindered olefins. Switching to indenylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate significantly expands the scope of the reaction to substrates bearing more substituted olefinic linkages and to cyclic substrates of rings containing eight or more members. The mechanism is probed by deuterium labeling, which shows that the metal catalyzes an intramolecular 1,3-hydrogen shift of the carbinol hydrogen to the terminal olefinic position.
- Trost, Barry M.,Kulawiec, Robert J.
-
p. 2027 - 2036
(2007/10/02)
-
- 71. Enantioselective Copper-Catalyzed 1,4-Addition of Grignard Reagents to α,β-Unsaturated Carbonyl Compounds
-
The enantioselective copper-catalyzed 1,4-addition of Grignard reagents to α,β-unsaturated carbonyl compounds was studied with the following Cu(I) compounds as catalyst precursor and 1,2:5,6-di-O-isopropylidene-3-thio-α-D-glucofuranose (Hsiig) as chiral l
- Spescha, Maurus,Rihs, Grety
-
p. 1219 - 1230
(2007/10/02)
-
- Preparation of polyfunctional diorganomercurials and their transmetallation to diorganozincs. Applications to the preparation of optically active secondary alcohols
-
Two new methods of preparation of functionalized diorganomercurials have been developed.The first method involves a substitution reaction of (ICH2)2Hg with zinc-copper reagents FG-RCu(CN)ZnI in THF/DMF at -60 deg C.Functional groups such as an ester, nitrile, ketone, phosphonate, halide, and boronic ester are tolerated in this reaction.The second method involves a reductive transmetallation between polyfunctional organozinc halides and mercurous chloride (Hg2Cl2).This very convenient procedure provides a rapid route to various functionalized diorganomercurials in good yields (61-89percent yield).The synthetic utility of these mercury organometallics is demonstrated.Their transmetallation with zinc dust (toluene, 80 deg C, 3-5 h) affords dialkylzincs which add enantioselectively to aldehydes in the presence of a catalytic amount (20 molpercent) of the norephedrine derivative 13.This transmetallation can also be used to prepare stereoselectively (E)-alkenylzinc halides (> 98percent E).Addition of Cl(H)ZrCp2 to (E)-5-chloropentenylzinc bromide in CH2Cl2 (25 deg C, 1 min) affords a 1,1-bimetallic of zinc and zirconium Cl(CH2)4CH(ZnBr)ZrCp2(Cl) which reacts stereoselectively with an aldehyde providing the (E)-disubstituted olefin (49percent yield; 100percent E).
- Rozema, Michael J.,Rajagopal, Duddu,Tucker, Charles E.,Knochel, Paul
-
-
- 1,1-DICHLORO-2,2,2-TRIFLUOROETHYL ZINC AND LITHIUM COMPOUNDS IN ASYMMETRIC SYNTHESIS
-
Addition of 1,1-dichloro-2,2,2-trifluoroethyl zinc chloride 2 complexed with optically pure ligands leads to zero percentage of asymmetric induction due to too large a distance between the chiral centers involved.However, addition of 2 and of the correspo
- Solladie-Cavallo, A.,Quazzotti, S.
-
p. 221 - 228
(2007/10/02)
-
- THE REACTION OF α,β-EPOXYSILANES WITH METALLATED ALKYLARYL SULPHONES. A NOVEL APPROACH TO ALLYLIC ALCOHOLS
-
Lithiated alkylaryl sulphones (2a-c) react with α,β-epoxysilane (1) to yield O-trimethylsilyl allylic alcohols (3a-c), predominantly as Z isomers.The BF3-assisted reaction followed by treatment of the adduct with nBu4NF affords allylic alcohols.
- Masnyk, Marek,Wicha, Jerzy
-
p. 2497 - 2500
(2007/10/02)
-
- N,O-HETEROCYCLES. XVI. DIRECT CONVERSION OF SOME ISOXAZOLIDINES INTO ALCOHOLS VIA α,β-ENONES
-
The 1,3-dipolar cycloadducts between nitrones and alkenes are converted into alcoholic derivatives by trimethyl phosphate and by subsequent reduction.The reaction of the substituted isoxazolidines, exempt of further functionalities, proceeds under the action of TMP through a sequence of steps including a Hofmann-like elimination with electronic-controlled orientation indicated also by thermochemical calculations.The overall process leads to the formation of saturated and unsaturated alcohols as known for the reduction step.
- Liguori, Angelo,Sindona, Giovanni,Uccella, Nicola
-
p. 369 - 374
(2007/10/02)
-