The stereochemistry of organometallic compounds. XV. Reactions of the allylpalladium complexes of α,β-unsaturated ketones and esters with nucleophiles

1977 ◽  
Vol 30 (3) ◽  
pp. 553 ◽  
Author(s):  
WR Jackson ◽  
JU Strauss
Keyword(s):  
Carbon Atom ◽  
Organometallic Compounds ◽  
Unsaturated Ketones ◽  
High Yields

Reactions of π-allylpalladium complexes of α,β-unsaturated ketones and esters with nucleophiles occur regioselectively at the γ-carbon atom to give high yields of γ-functionalized products. The E/Z-stereochemistry of the products is discussed in relation to the syn/anti- stereochemistry of the π-allylpalladium compounds and the reactivity of the latter compounds is discussed in terms of their 1H and 13C N.M.R. spectra.

Five-membered ring annulation via thermal rearrangement of β-cyclopropyl α,β-unsaturated ketones. A formal total synthesis of the sesquiterpenoid (±)-zizaene

1982 ◽  
Vol 60 (23) ◽  
pp. 2965-2975 ◽  
Author(s):  
Edward Piers ◽  
Jacques Banville ◽  
Cheuk Kun Lau ◽  
Isao Nagakura
Keyword(s):  
Total Synthesis ◽  
Sodium Methoxide ◽  
Membered Ring ◽  
Yield Reduction ◽  
Thermal Rearrangement ◽  
Standard Methods ◽  
Unsaturated Ketones ◽  
Mild Conditions ◽  
Sodium Amalgam ◽  
High Yields

Treatment of the β-iodo enones 7–10 with lithium (phenylthio)(cyclopropyl)cuprate provided excellent yields of the corresponding β-cyclopropyl α,β-unsaturated ketones 11–14, respectively. When 3-isopropenyl-2-cyclohexen-1-one (16) was allowed to react with dimethyloxosulfonium methylide in dimethyl sulfoxide – tetrahydrofuran, 3-(1-methylcyclopropyl)-2-cyclohexen-1-one (17) was produced in 59% yield. Although thermal rearrangement (~425–450 °C) of compounds 11 and 17 produced high yields of the annulation products 19 and 22, respectively, similar reactions involving the β-cyclopropyl enones 12 and 13 were not efficient in terms of production of the corresponding bicyclic systems (23, 26, and/or 27, respectively). In these cases, predominant (24 + 25 from 12) or significant (28 + 29 from 13) amounts of monocyclic dienones were formed. The annulation product 22 served as a convenient starting material for a new formal total synthesis of the sesquiterpenoid (±)-zizaene (30). Conjugate addition of lithium divinylcuprate to 22 afforded the ketone 36 which was converted by standard methods (via 38 and 39) into the enone 40. Treatment of the latter substance with thiophenol in the presence of tetra-n-butylammonium fluoride gave 41, which was transformed via ketalization (41 → 42), hydroboration(42 → 43), tosylation (43 → 44), and oxidation (44 → 45) into the sulfone 45. When the latter compound was treated with potassium tert-butoxide in hexamethylphosphoramide, the tricyclic ketal sulfone 46 was produced in 85% yield. Reduction of 46 with sodium amalgam afforded the ketal 47, which upon hydrolysis under mild conditions gave the ketone 32. Treatment of the latter substance with sodium methoxide in methanol provided a 1:2 mixture of the epimeric ketones 31 and 32, which had been converted previously by Coates and Sowerby into (±)-zizaene (30).

Lewis-acidic organometallic compounds of the lanthanides and the alkaline earth metals as catalysts for the activation of carbonyl groups

2001 ◽  
Vol 73 (2) ◽  
pp. 279-282 ◽  
Author(s):  
Herbert Schumann ◽  
Mario Glanz ◽  
Jochen Gottfriedsen ◽  
Sebastian Dechert ◽  
Dietmar Wolff
Keyword(s):  
Liquid Crystalline ◽  
Alkaline Earth ◽  
Molecular Mass Distribution ◽  
Organometallic Compounds ◽  
Carbonyl Groups ◽  
Competitive Reaction ◽  
Strontium Barium ◽  
X Ray ◽  
Distribution Index ◽  
High Yields

1,3-dialkyl-4,5-dimethylimidazol-2-ylidenes form adducts with various bis (alkylcyclopentadienyl) complexes of magnesium, calcium, strontium, barium, samarium, and ytterbium. The X-ray structures of selected metallocenes and carbene adducts are discussed. Liquid-crystalline homo- and block copolymers with a narrow molecular mass distribution index were obtained in high yields by living polymerization of mesogenic methacrylates with organosamarium complexes. Depending on the structure of the catalyst and the polarity of the solvent used, different, partially competitive reaction mechanisms are observed.

The Stereochemistry of Organometallic Compounds. XXVIII. The Nickel-Catalyzed Addition of Hydrogen Cyanide to Aliphatic Dienes

1987 ◽  
Vol 40 (6) ◽  
pp. 1053 ◽  
Author(s):  
EM Campi ◽  
PS Elmes ◽  
WR Jackson ◽  
CG Lovel ◽  
MKS Probert
Keyword(s):  
Hydrogen Cyanide ◽  
Organometallic Compounds ◽  
Mechanism Of Reaction ◽  
Wide Range ◽  
High Yields ◽  
Very High

Reaction of hydrogen cyanide with a wide range of aliphatic dienes in the presence of nickel(0) catalysts leads to rearrangement of the diene and formation of β,γ -unsaturated nitriles in moderate to very high yields. The mechanism of reaction is discussed in terms of π-allyl-nickel intermediates.

2,2-Bis(ethylthio)ethanenitrile: preparation and use as a one or two carbon nucleophile

1983 ◽  
Vol 61 (9) ◽  
pp. 2006-2009 ◽  
Author(s):  
Gordon S. Bates ◽  
S. Ramaswamy
Keyword(s):  
Potassium Salt ◽  
Alkylating Agents ◽  
Conjugate Addition ◽  
Carbon Chain ◽  
Chain Extension ◽  
High Yield ◽  
Unsaturated Ketones ◽  
High Yields

2,2-Bis(ethylthio)ethanenitrile 1 was prepared in high yield from 2,2-bis(ethylthio)ethanal 2. Alkylation of the potassium salt of 1 with various alkylating agents and conjugate addition to cyclic α,β-unsaturated ketones provided high yields of the alkylation products of 1. The potential one and two carbon chain extension capability of this new reagent has been demonstrated.

Tandem additions of 3,4-dihydroisoquinolines to γ-hydroxy-α,β-unsaturated ketones: a green and new access to oxazolo[2,3-a]tetrahydroisoquinolines

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91870-91874 ◽  
Author(s):  
Sheng-Han Huang ◽  
Yu-Wei Shih ◽  
Wen-Tse Huang ◽  
Deng-Hong Li ◽  
Te-Fang Yang
Keyword(s):  
Room Temperature ◽  
Addition Reactions ◽  
Unsaturated Ketones ◽  
High Yields ◽  
P Addition

Addition reactions of various 3,4-dihydroisoquinoline derivatives with γ-hydroxy-α,β-unsaturated ketones were carried out in 15 min at room temperature without an additive, providing oxazolo[2,3-a]tetrahydroisoquinoline derivatives in high yields.

scholarly journals Catalytic Asymmetric Synthesis of Geminal-Dicarboxylates

2018 ◽  
Author(s):  
Nisha Mistry ◽  
Stephen P. Fletcher
Keyword(s):  
Carbon Atom ◽  
Asymmetric Synthesis ◽  
Building Blocks ◽  
Enantiomeric Purity ◽  
Ring Closing Metathesis ◽  
Carbon Centers ◽  
Catalytic Asymmetric Synthesis ◽  
High Yields ◽  
Chiral Lactones ◽  
Oxygen Atoms

<p>Stereogenic acetals, spiroacetals and ketals are well-studied stereochemical features that bear two heteroatoms at a common carbon atom. These stereocenters are normally found in cyclic structures while linear (or acyclic) analogues bearing two heteroatoms are rare. Chiral geminal-dicarboxylates are illustrative, there is no current way to access this class of compounds while controlling the stereochemistry at the carbon center bound to two oxygen atoms. Here we report a rhodium-catalyzed asymmetric carboxylation of ester-containing allylic bromides to form stereogenic carbon centers bearing two different carboxylates with high yields and enantioselectivities. The products, which are surprisingly stable to a variety of acidic and basic conditions, can be manipulated with no loss of enantiomeric purity as demonstrated be ring closing metathesis reactions to form chiral lactones, which have been extensively used as building blocks in asymmetric synthesis.<br></p>

Regiospecific Aza-Michael Addition of 4-Aryl-1H-1,2,3-triazoles to Chalcones: Synthesis of 2,4-Disubstituted 1,2,3-Triazoles in Basic Medium

Synlett ◽  
2017 ◽  
Vol 29 (01) ◽  
pp. 99-105 ◽  
Author(s):  
Rama Peddinti ◽  
Ujjawal Bhagat
Keyword(s):  
Michael Addition ◽  
Basic Medium ◽  
Unsaturated Ketones ◽  
Metal Free ◽  
Michael Adducts ◽  
Donor Ability ◽  
High Yields

A novel metal-free and base-mediated method to display the donor ability of 1,2,3-triazoles for the synthesis of 2,4-disubstituted 1,2,3-triazoles has been developed. A DABCO-promoted aza-Michael addition of 4-aryl NH-1,2,3-triazoles to α,β-unsaturated ketones (chalcones) is presented. The reactions proceeded with complete regiospecificity in a 3:1 mixture of acetonitrile and methanol at 85 °C to provide 2,4-disubstituted 1,2,3-triazoles as Michael adducts, and the addition products 1,3-diaryl-(4-aryl-2H-1,2,3-triazol-2-yl)propan-1-ones were isolated in high yields.

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