2-Carbomethoxycyclopent-2-enone

Marx, John N.; Cox, James H.; Norman, Lewis R.

doi:10.1021/jo00799a602

Cited by 42 publications

(38 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[10] Therefore, this is the first enantioselective synthesis of compounds 7a-i, which are versatile intermediates as they contain multiple, separately addressable reaction sites apart from the still intact b-ketoester functionality. [11] More general, standard, non-quinone type unsaturated b-ketoesters have been rarely used as dienophiles, and only one catalytic system has been previously reported to accomplish enantioselective Diels-Alder reactions with such substrates.…”

Section: Catalysis Resultsmentioning

confidence: 99%

Enantioselective Diels-Alder Reactions of Unsaturated ?-Ketoesters Catalyzed by Chiral Ruthenium PNNP Complexes

Schotes

Mezzetti²

2011

Chimia

View full text Add to dashboard Cite

We report here dicationic ruthenium PNNP complexes that promote the enantioselective Diels-Alder reaction of alpha-methylene beta-ketoesters with various dienes. Complex [Ru(OEt2)2(PNNP)](PF6)2, formed in situ from [RuCl2,(PNNP)] and (Et3O)PF6 (2 equiv.), catalyzes the Diels-Alder reaction of such unsaturated beta-ketoesters to give novel alkoxycarbonyltetrahydro-1-indanone derivatives (nine examples) with up to 93% ee. The crystal structure of the substrate-catalyst adduct shows that the lower face of the substrate is shielded by a phenyl ring of the PNNP ligand, which accounts for the high enantioselectivity. The attack of the diene from the open re enantioface of the unsaturated beta-ketoester is consistent with the absolute configuration of the product. A useful application of this method is the reaction with Dane's diene to give estrone derivatives with up to 99% ee and an ester-exo:endo ratio of up to 145:1 (after recrystallization). Besides the enantioselective formation of all-carbon quaternary centers, this methodology is notable because unsaturated beta-ketoesters have been rarely used in Diels-Alder reactions. Furthermore, enantiomerically pure estrone derivatives are interesting in view of their potential applications, including the treatment of breast cancer.

show abstract

Section: Catalysis Resultsmentioning

confidence: 99%

Enantioselective Diels-Alder Reactions of Unsaturated ?-Ketoesters Catalyzed by Chiral Ruthenium PNNP Complexes

Schotes

Mezzetti²

2011

Chimia

View full text Add to dashboard Cite

show abstract

“…9 Our initial exploratory efforts directed towards the dehydrogenation of 17 involved the use of selenoxide elimination. 10 Disappointingly, the reaction did not proceed with 17 being recovered, unaltered. …”

Section: Methodsmentioning

confidence: 99%

DFT calculations of pentalenoquinones: towards the interception of 2-bromopentalene-1,5-dione

Atalar¹,

Algı²,

Balcı³

2008

Arkivoc

View full text Add to dashboard Cite

To reveal the stability and the aromatic character of pentalenoquinones (PQs) 1-4 and the corresponding bromo derivatives (Br-PQs) 6-9, DFT calculations (B3LYP/6-311+G(d,p)) concerning the geometry optimization, total energy and nucleus independent chemical shift (NICS) values were performed. It was found that all of the compounds have planar geometry. As the energy difference between HOMO-LUMO energy levels (∆ε=ε LUMO -ε HOMO ) and total energies were considered for the pentalene family, the stability order was found to be 1 > 2 > 3 > 4 for PQs, and 6 > 7 > 8 > 9 for Br-PQs. Furthermore 2-bromopentalene-1,5-dione (6) in solution was investigated and noted that it was too reactive to be isolated or even trapped.

show abstract

“…They should a priori show similar reactivity as alkylidenemalonates. The tested substrates include α-alkylidene-β-ketonitriles (221, 222), [114] 2-methoxycarbonyl-cyclopent-2-enone (223), [115] five-and six-membered α-alkylidene-β-diketones (224, 225), [116] commercially available 3-acetylcumarine (226), and 3-ethoxycarbonylcumarine (227). These compounds were chosen as substrates taking into account that some of the expected addition products are precursors of natural carbocyclic compounds with important biological activity.…”

Section: Addition To Activated Cyclic Alkenesmentioning

confidence: 99%

Aldehyde N,N‐Dialkylhydrazones as Neutral Acyl Anion Equivalents: Umpolung of the Imine Reactivity

et al. 2007

View full text Add to dashboard Cite

The isoelectronic replacement of the α‐carbon of enamines by nitrogen leads to the corresponding hydrazones, and thus, they can be termed “aza‐enamines”. Hence, aldehyde N,N‐dialkylhydrazones enable analogous electrophilic substitutions at the imine carbon that corresponds to the β‐carbon of enamines. In addition, after hydrolysis of the product hydrazones to the parent ketones or aldehydes, these reactions constitute an umpolung of the classical carbonyl reactivity and overall a nucleophilic acylation or formylation. This review covers the aza‐enamine chemistry from its very beginning in the late 1960s up to this year. In the first part, reactions of aromatic, aliphatic, and heterocyclic aldehyde N,N‐dialkylhydrazones with highly reactive substrates such as the Vilsmeier and Mannich reagents, sulfonyl isocyanates, perfluoroacetic anhydride, and inorganic electrophiles such as halogens and phosphorus tribromide are described. The hydrazones of α,β‐unsaturated aldehydes react as vinylogous aza‐enamines at the terminal carbon providing unsaturated aldehydes. As electron‐rich dienes and dienophiles, they also form Diels–Alder adducts and thus interesting N‐heterocycles. The second part covers carbon–carbon bond formations of the sterically less‐demanding formaldehyde N,N‐dialkylhydrazones with synthetically very useful electrophiles such as various Michael acceptors and carbonyl compounds. Formaldehyde SAMP‐hydrazone and related derivatives generally give excellent asymmetric inductions. Finally, first organocatalytic versions of the aza‐enamine chemistry are presented. In summary, the rich chemistry of aldehyde N,N‐dialkylhydrazones as neutral acyl anion, formyl anion, and cyanide equivalents is demonstrated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

show abstract

2-Carbomethoxycyclopent-2-enone

Cited by 42 publications

References 3 publications

Enantioselective Diels-Alder Reactions of Unsaturated ?-Ketoesters Catalyzed by Chiral Ruthenium PNNP Complexes

Enantioselective Diels-Alder Reactions of Unsaturated ?-Ketoesters Catalyzed by Chiral Ruthenium PNNP Complexes

DFT calculations of pentalenoquinones: towards the interception of 2-bromopentalene-1,5-dione

Aldehyde N,N‐Dialkylhydrazones as Neutral Acyl Anion Equivalents: Umpolung of the Imine Reactivity

Contact Info

Product

Resources

About