81255-96-1

Upstream product

• 59376-62-4 (1E,4E)-1-(trimethylsilyl)-5-phenylpenta-1,4-dien-3-one 
• 102-92-1 cinnamoyl chloride 
• 754-05-2 ethenyltrimethylsilane 
• 14275-61-7 (E)-1,2-bis(tri-n-butylstannyl)ethene 
• 100-52-7 benzaldehyde 
• 75-36-5 acetyl chloride 
• 110456-76-3 4-phenyl-5-chloro-2-cyclopentenone 
• 81256-03-3 (1E,4E)-5-phenyl-1-trimethylsilyl-1,4-pentadien-3-ol 
• 14371-10-9 (E)-3-phenylpropenal 
• 548774-28-3 C₁₄H₁₈OSi 
• 193685-91-5 (E)-1-phenylpent-1-en-4-yn-3-yl acetate 
• 104-55-2 3-phenyl-propenal 
• 74-86-2 acetylene 

Downstream Products

• 2758-18-1 3-Methyl-2-cyclopenten-1-one 
• 3810-26-2 3-phenyl-2-cyclopenten-1-one 

Relevant academic research and scientific papers

Hydroxylic additives enhance yield and scalability of silicon-directed Nazarov reaction

As a result of difficulties in scaling up silicon-directed Nazarov cyclization for use in the synthesis of taxane natural products, the effect of additives was examined. Hydroxylic additives were found to convey a consistent beneficial effect on the rate, overall yield, and scalability of these reactions. Optimal conditions (1.5 equiv methanol or water with substoichiometric FeCl3), were successfully applied to a range of β-silyl dienone substrates, including several complex polycyclic examples, as well as simpler dienones previously shown to be low-yielding or completely unreactive under the conventional conditions.

"Silver effect" in gold(I) catalysis: An overlooked important factor

Clear experimental evidence from X-ray photoelectron spectroscopy and 31P NMR spectroscopy has been obtained for the first time to confirm that the combination of Ag+ cation with [L-Au]+ results in the formation of different complexes in solution. Re-evaluation of literature-reported gold-catalyzed reactions revealed a significant difference in the reactivities with and without silver. In extreme cases (more than "rare"), the conventional [L-Au]+ catalysts could not promote the reaction without the presence of silver. This investigation has therefore revealed a long-overlooked "silver effect" in gold catalysis and should lead to revision of the actual mechanism.

Tetramethylnorbornadiene, a versatile alkene for cyclopentenone synthesis through intermolecular Pauson-Khand reactions

1,2,3,4-Tetramethyl-bicyclo[2.2.1]hepta-2,5-diene (TMNBD, for tetramethylnorbornadiene) has been prepared and used successfully as an acetylene equivalent in the synthesis of substituted cyclopentenones. TMNBD is easily accessible on a multigram scale and displays excellent reactivity toward the intermolecular Pauson-Khand reaction. Conjugate additions on the resulting tricyclic compounds proceed with exquisite diastereoselectivity. The retro-Diels-Alder reaction of these TMNBD derivatives occurs under much smoother conditions than those required for its norbornadiene homologues.

Polymer-mediated reactions. A Nazarov-like cyclization

The polymer PEDOT+ mediates a Nazarov-like cyclization of dienones, in an heterogeneous system and in hydrocarbon solvents. The polymer-mediated reactions show clear differences in product formation when compared to the same reaction with tosic acid, or when compared to reports in the literature. Comparable or improved yields are observed, as well as the ability to give a -Nazarov product in cases where treatment with acid fails to give cyclization, or leads to an undesirable rearrangement. In addition, the ability to recycle the polymer makes this a potentially useful protocol for an important organic chemical reaction. Georg Thieme Verlag Stuttgart · New York.

A Pauson-Khand-type reaction between alkynes and olefinic aldehydes catalyzed by rhodium/cobalt heterobimetallic nanoparticles: An olefinic aldehyde as an olefin and CO source

Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co 2Rh2(CO)12 react with alkynes and α,β-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. α,β-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.

Asymmetric [2+2+1] cyclopentannulation of olefins. Ring expansion of 2-N-methyl-N-tosyl-cyclobutanone

α-N-Methyl-N-tosyl cyclobutanones 2 which had been previously prepared in good yields and high enantiomeric excesses from olefins and chiral keteniminium salts have been converted into the corresponding oxiranes 3 by reaction with dimethylsulfonium methylid. The stereochemistry of this reaction was found to be dependent on several factors which have been analyzed. Treatment of these oxiranes with a stoichiometric amount of lithium iodide in refluxing tetrahydrofuran gave excellent yields of monocyclic or fused cyclopentenones 4 resulting from a β-elimination of N-methyl-N-tosylamide from a primarily formed cyclopentanone. The ring-expansion was totally selective but for oxiranes attached to a bicyclo[4.2.0]octanone system. In all cases, the enantiomeric purities of the starting cyclobutanones were preserved throughout the sequence which thus represents a useful [2+2+1] strategy for the cyclopentannulation of olefins.

A [2+2+1] strategy for the conversion of olefins into cyclopentenones. Ring expansion of 2-N-methyl-N-tosylcyclobutanones

α-N-Methyl-N-tosylcyclobutanones prepared by asymmetric cycloadditions of the corresponding keteniminium triflate to olefins have been converted into a mixture of epoxides using dimethylsulfonium ylide. Treatment of these epoxides with lithium iodide unexpectedly yielded the corresponding cyclopentenones. This sequence amounts to a [2+2+1] cyclopentannulation of an olefin.

Acyclic O- and N-substituted Pentadienyl Cations: Structural Characterisation, Cyclisation and Computational Results

A number of 1- and 3-hydroxy and 1-amino substituted acyclic pentadienyl cations have been characterised by NMR spectroscopy in situ at low temperature.Some of the 3-hydroxy cations undergo cyclisation to give 1-hydroxycyclopentenyl cations which on deprotonation give substituted cyclopentenones.

Intramolecular Cooperative Reactions of 1,2-Bis(diazoketone)s. The First Syntheses of trans-Hydro-1H-2-inden-1-ones

The intramolecular cooperative reactions of 1,2-bis(diazoketone)s initiated by the Wolff rearrangement of α-diazoketones have been investigated.Under thermal conditions, 1,2-bis(diazoketone)s are efficiently transformed into 2-cyclopenten-1-one derivatives with complete stereospecificity.Thus, a most extraordinary result is reported, that trans-hydro-2-inden-1-ones (1-3) were synthesized for the first time from trans-1,2-bis(diazoketone)s (5, 11, and 12), respectively.The unprecedented trans-hydroindenone structure was confirmed by X-ray analysis of 3 as well as 1H NMR analysis and was supported by ab initio molecular orbital calculations.The same reactions were also carried out under photochemical conditions and were applied to 1,3-bis(diazoketone)s, giving 2-cyclohexen-1-one derivatives.

Novel Synthesis of trans-Hydroindenones by Thermal Reaction of α,ω-Bis(diazo)diketones

Thermal reaction of α,ω-bis(diazo)diketones gives α,β-unsaturated cycloalkenones including unsubstituted trans-hydroindenones, which were difficult to access by the conventional synthetic reactions.