Anti-Markovnikov Hydration Of Terminal Alkynes Research Articles

Mixed Phosphane η5-CpRuCl(PR3)2 Complexes as Ambifunctional Catalysts for Anti-Markovnikov Hydration of Terminal Alkynes

The catalytic activity of [CpRu(L)(2)(MeCN)]PF(6) (L = 2-diphenylphosphinopyridine with bulky groups at C-6) for anti-Markovnikov hydration of terminal alkynes to aldehydes is retained when one heterocyclic ligand L is replaced by L' = PPh(3). Equal amounts of CpRuCl(PPh(3))(2) (1) and phosphane L in acetone solution equilibrate to a mixture of 1, CpRuCl(L)(PPh(3)) (2), and CpRuCl(L)(2) (3), which acts as highly active in situ catalyst for preparative anti-Markovnikov hydration of alkynes in water-rich media (2 mol % [Ru], 60 °C, 3-18 h in 4:1 (v/v) acetone/water). Reactions were completed in <15 min at 160 °C.

CpRu(η6-naphthalene)]PF6 as Precursor in Complex Synthesis and Catalysis with the Cyclopentadienyl-Ruthenium(II) Cation

The complex [CpRu(η6-naphthalene)]PF6 (2) is a readily accessible and air-stable source of the CpRu+ fragment (Cp = η5-C5H5) for applications in complex synthesis and catalysis. The utility of this precursor complex is demonstrated in a number of experiments: The counterion of 2 is exchanged by reaction with cinchonidinium Δ-TRISPHAT to give [CpRu(η6-naphthalene)]Δ-TRISPHAT (4; with X-ray crystal structure). Ligand exchange of 2 in acetonitrile with (Z,Z)-1,5-cyclooctadiene (COD) produces [CpRu(η2:η2-COD)(MeCN)]PF6 (5; with X-ray crystal structure); with chelating phosphanes (P−P), complexes [CpRu(P−P)(MeCN)]PF6 are selectively generated, and starting with a 1,4-diazadiene, a solvento complex [CpRu(diazadiene-N,N′)(MeCN)]PF6 is obtained. Stepwise reaction of 2 (or 4) in acetonitrile with different monodentate phosphanes PR3 and PR′3 first gives [CpRu(PR3)(MeCN)2]+ (I), then the chiral-at-metal cation [CpRu(PR3)(PR′3)(MeCN)]+ (II), which was resolved spectroscopically (31P NMR) when combined with the enantiopure Δ-TRISPHAT counterion. Complex cations of type I or II incorporating 2-diphenylphosphinopyridines as ligands display either the η1-P or the chelating η2-P,N coordination mode, depending on the size of the ligand and, in solution, the solvent. Reaction of 2 with 3 equiv of triarylphosphanes (PR3) in hot acetone gives rise to [CpRu(PR3)3]+, including the previously unknown cation [CpRu(PPh3)3]+. The in situ combination of 2 and 2 equiv of bulky 6-substituted 2-pyridylphosphanes catalyzes the anti-Markovnikov hydration of terminal alkynes to aldehydes. Either complex 2 or 5 catalyzes the [2+2+2]-cycloaddition of COD with alkynes. Complex 5 is a catalyst for the coupling of allyl alcohols with terminal alkynes to give 4-alkenones.

The AZARYPHOS Family of Ligands for Ambifunctional Catalysis: Syntheses and Use in Ruthenium‐Catalyzed anti‐Markovnikov Hydration of Terminal Alkynes

The family of AZARYPHOS (aza-aryl-phosphane) phosphane ligands, containing a phosphine unit and sterically shielded nitrogen lone pairs in the ligand periphery, is introduced as a tool for developing ambifunctional catalysis by the metal center and nitrogen lone pairs in the ligand sphere. General synthetic strategies have been developed to synthesize over 25 examples of structurally diverse (6-aryl-2-pyridyl)phosphanes (ARPYPHOS), (6-alkyl-2-pyridyl)phosphanes (ALPYPHOS), 4,6-disubsituted 1,3-diazin-2-ylphosphanes or 1,3,5-triazin-2-ylphosphanes, quinazolinylphosphanes, quinolinylphosphanes, and others. The scalable syntheses proceed in a few steps. The incorporation of AZARYPHOS ligands (L) into complexes [RuCp(L)(2)(MeCN)][PF(6)] (Cp = cyclopentadienyl) gives catalysts for the anti-Markovnikov hydration of terminal alkynes of the highest known activities. Electronic and steric ligand effects modulate the reaction kinetics over a range of two orders of magnitude. These results highlight the importance of using structurally diverse ligand families in the process of developing cooperative ambifunctional catalysis by a metal and its ligand.

Catalysts through self-assembly for combinatorial homogeneous catalysis

Abstract Inspired by the principle of DNA base-pairing, a new concept for the self-assembly of molecular catalysts is described herein. Thus, employing A-T analogous complementary hydrogen-bonding templates, self-assembly of monodentate to bidentate ligands in the coordination sphere of a transition-metal salt occurs to give defined self-assembly catalysts. This approach is intrinsically combinatorial and allows the facile generation of defined catalyst libraries through simple component mixing. From the study of these ligand libraries, excellent catalysts for linear-selective hydroformylation, asymmetric hydrogenation, and anti-Markovnikov hydration of terminal alkynes have emerged.

Iterative Synthesis of Oligo-1,4-diols via Catalytic Anti-Markovnikov Hydration of Terminal Alkynes

A sequential, iterative synthesis of oligo-1,4-diol building blocks has been realized via (a) propargylation of an aldehyde with allenylzinc bromide, (b) alcohol protection and (c) ruthenium-catalyzed anti-Markovnikov hydration of the terminal alkyne to release an aldehyde for the next iteration. Linear chains with 1,4-, 1,4,7- 1,4,7,10- and 1,4,7,10,13- functionalization patterns have been obtained by consecutive sequential iterations.

Catalytic Hydration of Alkynes and Its Application in Synthesis

The catalytic addition of water to alkynes (hydration) generates valuable carbonyl compounds from unsaturated hydrocarbon precursors. Traditional mercury(II) catalysts hydrate terminal alkynes with Markovnikov selectivity to methyl ketones. Much research has been devoted to finding catalysts based on less toxic metals, the most promising being gold(I), gold(III), platinum(II), and palladium(II). Catalytic anti-Markovnikov hydration of terminal alkynes to aldehydes has been realized in an efficient manner with ruthenium(II) complex catalysts. The present review article lists known hydration catalysts and discusses applications of catalytic hydration to different classes of substrates, with an emphasis on functional group tolerance and regioselectivity.

Highly Active in Situ Catalysts for Anti-Markovnikov Hydration of Terminal Alkynes

The anti-Markovnikov hydration of terminal alkynes to give aldehydes is catalyzed by complexes derived in situ from air-stable [CpRu(eta6-naphthalene)]PF6 (C) and 6-aryl-2-diphenylphosphinopyridines (L). Ligands L are readily available from a modular synthesis. Increasing the size of the ligand C-6 aryl group in the order R = Ph < mesityl < 2,4,6-triisopropylphenyl < (2,4,6-triphenyl)phenyl gave hydration catalysts of highest known activity. [reaction: see text]

Bifunctional Organometallic Catalysts Involving Proton Transfer or Hydrogen Bonding

Inspired by the cooperativity displayed by metalloenzymes, bifunctional organometallic complexes featuring pendant basic functional groups are designed and evaluated as catalysts in reactions for which enzymes are not suited. Anti-Markovnikov hydration of terminal alkynes is the focus, as are hydrogen bonding and proton transfer facilitated by the pendant groups.

A General Bifunctional Catalyst for the anti‐Markovnikov Hydration of Terminal Alkynes to Aldehydes Gives Enzyme‐Like Rate and Selectivity Enhancements.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A general bifunctional catalyst for the anti-Markovnikov hydration of terminal alkynes to aldehydes gives enzyme-like rate and selectivity enhancements.

A new, bifunctional catalyst for anti-Markovnikov hydration of terminal alkynes to aldehydes (6) allows practical room-temperature hydration of alkyl-substituted alkynes. Other outstanding features include near-quantitative aldehyde yields from both alkyl- and aryl-substituted alkynes and wide functional group tolerance. The uncatalyzed rate of alkyne hydration is measured for the first time, showing the enzyme-like rate and selectivity enhancements of aldehyde formation by 6. For aldehyde formation, an uncatalyzed rate <1 x 10-10 mol h-1 means a half-life >600 000 years. The catalyzed rate is up to 23.8 mol (mol 6)-1 h-1 and 10 000:1 ratio in favor of aldehyde. Changes in rate and selectivity induced by 6 are thus >2.4 x 1011 and 300 000, respectively.

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes The support of San Diego State University is acknowledged.

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes The support of San Diego State University is acknowledged.

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes The support of San Diego State University is acknowledged.

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes The support of San Diego State University is acknowledged.

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes

Combined Effects of Metal and Ligand Capable of Accepting a Proton or Hydrogen Bond Catalyze Anti-Markovnikov Hydration of Terminal Alkynes

A binding pocket for water is created in 1 by the imidazolyl phosphane ligands and the RuII center. Compound 1 proves to be an excellent catalyst for a highly selective anti-Markovnikov hydration of terminal alkynes to give aldehydes rather than isomeric ketones under near-neutral conditions (aldehyde-to-ketone ratio up to 1000:1).

Ruthenium complex-catalyzed anti-Markovnikov hydration of terminal alkynes.

[reaction: see text]. Highly regioselective, efficient, and substituent-tolerant anti-Markovnikov hydration of terminal alkynes occurs to give n-aldehyde by use of a catalytic amount of easily available cyclopentadienylruthenium complexes bearing appropriate bidentate or monodentate phosphine ligands. Typically, RuCpCl(dppm) (1 mol %) catalyzes the addition of water to 1-hexyne at 100 degrees C to give hexanal in 95% yield: 2-hexanone is not detected at all.

ルテニウム触媒によるアルキンヘの付加反応

Additions to C-C multiple bonds are simple and the most efficient methods in organic synthesis in terms of atom utilization due to avoidance of stoichiometric amounts of by-products. The following catalytic C-C, C-O and C-N bond-constructions by direct additions of nucleophiles to alkynes catalyzed by ruthenium complexes have been developed. 1) Dimerization of terminal alkynes to 1, 4-disubstituted butatriens which is an unusual tail-to-tail coupled product. 2) The first example of anti-Markovnikov hydration of terminal alkynes to aldehydes. 3) Intermolecular hydroamination of terminal alkynes with anilines to imines. Some of the reactions proceed in high yields under solvent-free, open-air conditions. Theoretical studies were also performed about transformation of η2-coordinated 1-alkynes to vinylidene complexes which plays important role in regioselectivity of the addition reactions.

The First Anti-Markovnikov Hydration of Terminal Alkynes: Formation of Aldehydes Catalyzed by a Ruthenium(II)/Phosphane Mixture.

With the right auxiliary phosphane ligands-for example, pentafluorophenyldiphenylphosphane or the sodium salt of 3,3',3″-phosphinidynetris(benzenesulfonic acid)-the ruthenium(II)-catalyzed hydration of terminal alkynes to aldehydes proceeds by the previously unknown anti-Markovnikov addition of water [Eq. (a)]. Complexes of the type [RuCl2 (PR2 R2' R″)x ] (R=alkyl, Ph) are discussed as catalytically active species.

The First Anti-Markovnikov Hydration of Terminal Alkynes: Formation of Aldehydes Catalyzed by a Ruthenium(II)/Phosphane Mixture

With the right auxiliary phosphane ligands—for example, pentafluorophenyldiphenylphosphane or the sodium salt of 3,3′,3″-phosphinidynetris(benzenesulfonic acid)—the ruthenium(II)-catalyzed hydration of terminal alkynes to aldehydes proceeds by the previously unknown anti-Markovnikov addition of water [Eq. (a)]. Complexes of the type [RuCl2(PR2R2′R″)x] (R=alkyl, Ph) are discussed as catalytically active species.