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Topic: Ene reaction

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Group transfer reaction

	Organic reaction - Wikipedia, the free encyclopedia
		In organic synthesis, organic reactions are used in the construction of new organic molecules.
		The stereochemistry of pericyclic reactions is governed by the Woodward-Hoffmann rules and that of many elimination reactions by the Zaitsev's rule.
		Organic reactions can be categorized based on the type of functional group involved in the reaction as a reactant and the functional group that is formed as a result of this reaction.
	en.wikipedia.org /wiki/Organic_reaction (730 words)

	PhD Summary
		Reaction of tris(trimethylsilyl)germyl lithium (1') with 2-adamantanone in hexane leads to the formation of the thermally unstable 1,2-digermacyclobutane 8 (which structure was assigned on the basis of a X-ray analysis of a single crystal) via the the germene 9 (equation 5).
		Reaction of 1 with the sterically crowded di-tert-butyl ketone (15), 2,2,6,6-tetramethylcyclohexanone (16), fenchone (17), 2,2-dimethylcamphor (18), diadamantylketone (19) and 1-methyl-2-adamantanone (20) in hexane or benzene was studied.
		Reaction of 1 with acetophenone in hexane at -78 ºC gave after aqueous work-up the starting ketone due to the formation of the corresponding enolate, a process which could not be suppressed.
	www.chem.utah.edu /faculty/zharov/group/msc.htm (1712 words)

	Non-ionic Chemical Reactions (Site not responding. Last check: 2007-11-03)
		An electrocyclic reaction is the concerted cyclization of a conjugated
		Reaction 4 is drawn as a retro ene reaction, although this has not been demonstrated to be general for all reactions of allylic alcohols with thionyl chloride.
		Equation 5 illustrates an unusual "magnesium ene reaction" in which a Grignard function moves to a new location before reacting with an electrophilic reagent such as CO Because this is an intramolecular ene reaction a new ring is formed.
	www.cem.msu.edu /~reusch/VirtualText4/pericycl.htm (4865 words)

	Non-ionic Chemical Reactions
		An electrocyclic reaction is the concerted cyclization of a conjugated π-electron system by converting one π-bond to a ring forming σ-bond.
		Ene reactions are favored when the hydrogen accepting reagent, the "enophile", is electrophilic.
		Since ene reactions usually involve coupled bond-making & bond-breaking operations asociated with short π-electron systems (2 or 3 carbons), their stereospecificity is almost always suprafacial with respect to both components.
	www.cem.msu.edu /~reusch/VirtualText/pericycl.htm (5184 words)

	research
		Reactions occurring in cascade are emerging as powerful tools for the diastereoselective formation of multiple carbon-carbon bonds.
		A careful analysis of the reaction mechanism indicates that the stereochemical outcome of the tandem process is controlled by the conformational preferences of the macrocycles at the transition state for the Claisen (2→3) and ene (3→4) reactions.
		Penostatin F is a metabolite isolated from a fungal strain of Penicillium sp.
	www.science.uottawa.ca /~lbarriau/research.htm (1077 words)

	Process and intermediates for the synthesis of Vitamin D.sub.3 metabolites and chenodeoxycholic acid - Patent 4360470
		The ene reaction, which is known in the prior art, involves the addition of a compound with a double bond (enophile) to an olefin possessing an allylic hydrogen (ene) and involves allylic shift of the double bond, transfer of the allylic hydrogen to the enophile and bonding between the two unsaturated termini.
		This reaction may be carried out in any conventional inert solvent, for example, methylene chloride, carbon tetrachloride, chloroform, aromatic hydrocarbons such as benzene, toluene and the like, and lower aliphatic hydrocarbons such as hexane, octane and the like.
		The reaction is catalyzed by Lewis acids such as lower alkyl aluminum dihalides and aluminum trihalides in weak base as exemplified by ethylaluminum dichloride, aluminum tribromide with pyridine and aluminum chloride with pyridine.
	www.freepatentsonline.com /4360470.html (5310 words)

	R
		In the formalism of "transition-state theory", the reaction coordinate is that coordinate in a set of curvilinear coordinates obtained from the conventional ones for the reactants which, for each reaction step, leads smoothly from the configuration of the reactants through that of the transition state to the configuration of the products.
		An elementary reaction, constituting one of the stages of a stepwise reaction in which a reaction intermediate (or, for the first step, the reactants) is converted into the next reaction intermediate (or, for the last step, the products) in the sequence of intermediates between reactants and products.
		The elementary reaction or reaction stage (of a molecular rearrangement) in which there is both making and breaking of bonds between atoms common to a reactant and a reaction product or a reaction intermediate.
	www.chem.qmul.ac.uk /iupac/gtpoc/R.html (2950 words)

	Nitroso know-how (Site not responding. Last check: 2007-11-03)
		Leach and Houk's mechanism for the ene reaction between HNO and propene Org.
		Their main conclusion is that the reaction takes place in a stepwise manner: initial addition of the nitroso compound to the alkene occurs to give a diradical intermediate (2) with a new C-N bond, which then undergoes intramolecular hydrogen atom transfer from carbon to oxygen to give the product (4).
		In the nitroso ene reactions considered, a mechanism in which such rotations occurred would still lead to the same products, but some of the KIEs would be different.
	www.rsc.org /chemistryworld/Issues/2003/June/nitroso.asp (788 words)

	Pericyclic Reaction Chemistry
		Sigmatropic reactions involve the movement of a sigma-bond with the simultaneous rearrangement of the pi-system.
		An example of an ene reaction is seen with the reaction of methylenecyclohexene and methyl acrylate.
		A common reaction in organic synthesis is the acid catalysed decarboxylation of a beta-ketoester.
	www.meta-synthesis.com /webbook/49_pericyclic/pericyclic.html (1568 words)

	Journal of the Brazilian Chemical Society - Intramolecular ene reactions catalyzed by NbCl5, TaCl5 and InCl3 (Site not responding. Last check: 2007-11-03)
		The carbonyl-ene reaction is synthetically very useful since it enables the formation of a C-C bond with the construction of two vicinal chiral centers.
		The second type of ene reaction we studied was the cyclization of compound 6 which was prepared by the Knoevenagel condensation of citronellal with diethylmalonate (Scheme 2) according to a known procedure.
		The reaction was stirred at room temperature and the consumption of the reagent was monitored by GC and/or TLC.
	www.scielo.br /scielo.php?pid=S0103-50532004000600005&script=sci_arttext&tlng=en (2104 words)

	Asymmetric Induction via an Intramolecular Haloetherification Reaction of Chiral Ene Acetals (Site not responding. Last check: 2007-11-03)
		This extremely high stereoselectivity in haloetherification reaction is probably due to a large stability difference between the two cis-intermediate, since endo-isomer has a large steric repulsion not only between the substituents and the bicyclo[2.2.1]heptane skeleton but also between the 1,3-dioxolane skeleton and the bicyclo[2.2.1]heptane skeleton as discussed in our earlier paper.
		High selectivity in these haloetherification reaction could be due to the preference of the intramolecular reaction over that of the intermolecular one, in addition to the high reactivity of norbornene olefin to form the bromonium ion because of its non-hyperconjugated character.
		In this case, since both the norbornene olefin and the diol olefin are equidistant from the acetal oxygen and in addition, both the olefins are expected to form a 5-membered transition state with the acetal oxygen, it is of great interest to examine their relative reactivities.
	www.ch.ic.ac.uk /ectoc/echet98/pub/011 (4364 words)

	E
		An "electrophilic substitution reaction" is a heterolytic reaction in which the reagent supplying the entering group acts as an electrophile.
		A reaction for which no reaction intermediates have been detected or need to be postulated in order to describe the chemical reaction on a molecular scale.
		The addition of a compound with a double bond having an allylic hydrogen (the "ene") to a compound with a multiple bond (the "enophile") with transfer of the allylic hydrogen and a concomitant reorganization of the bonding, as illustrated below for propene (the "ene") and ethene (the "enophile").
	www.chem.qmul.ac.uk /iupac/gtpoc/E.html (2409 words)

	Home
		The ene reaction is a pericyclic process between an alkene (the “ene”) with an allylic hydrogen and an enophile containing a double bond.
		In our group we study the ene reaction, in which the enophile in activated by an electron withdrawing group, and the carbonyl ene reaction where the enophile is an aldehyde.
		When forming six-membered rings via the ene reaction, the trans product is usually favoured, as the preferred reactive conformation is a pseudo-chair in which the bulky groups lie pseudo-equatorial.
	www.chem.bham.ac.uk /labs/snaith/stereo.htm (379 words)

	Expert: Polymer Synthesis and Properties, Catalysis, Physical-Organic Chemistry, and Molecular Modeling Expert
		Expert is also familiar with nickel-catalyzed aromatic coupling reactions to form biaryls using aryl chlorides and bromides and published a paper on the mechanism of this reaction.
		His interest in understanding organic and organometallic reaction mechanisms has been one of the underlying themes of his research in polymer chemistry and catalysis.
		He has investigated, for example, the mechanisms of nickel-catalyzed coupling reactions, the thermal decomposition of polyesters, nucleophilic displacement chemistry, and reaction kinetics for several systems.
	www.intota.com /viewbio.asp?bioID=773234&perID=722763 (1566 words)

	Alder-Ene Reaction (Site not responding. Last check: 2007-11-03)
		This allylic system reacts similarly to a diene in a Diels-Alder Reaction, while in this case the other partner is called an enophile, analogous to the dienophile in the Diels-Alder.
		The reaction requires higher temperatures because of the higher activation energy and stereoelectronic requirement of breaking the allylic C-H σ-bond.
		While mechanistically different, the Ene reaction can produce a result similar to the Prins Reaction.
	www.organic-chemistry.org /namedreactions/alder-ene-reaction.shtm (160 words)

	Professor Christopher S. Foote (Site not responding. Last check: 2007-11-03)
		A mechanistic example is the use of primary and secondary isotope effect studies to demonstrate the intermediacy of a perepoxide in the ene reaction of singlet oxygen with alkenes.18 A particularly interesting case involves trans-cyclooctene.
		Reaction of trans-cyclooctene with the analogous enophile phenyltriazolinedione gives an analogous inter aziridine imide, which is stable enough to be characterzied by NMR at low temperatures.19
		In summary, techniques from preparative and physical-organic chemistry and biochemistry are used as necessary to establish the role of key reactions of singlet oxygen or other species in chemical systems that are important to organic, biological, and medical science.
	www.chem.ucla.edu /dept/Organic/CSF_Brochure.html (1185 words)

	Millsaps College - Chemistry Department (Site not responding. Last check: 2007-11-03)
		With the study of singlet oxygen reactions, we gain an insight into the mechanisms of these harmful reactions.
		This reaction is generally accepted to occur through a perepoxide intermediate.
		Our group is interested in utilizing aqueous and hydroxylic solvents in the ene reaction and determining the effects on the intermediate perepoxide.
	www.millsaps.edu /chem/stensaas.shtml (205 words)

	APURBA BHATTACHARYA
		Asymmetric induction in carbon-carbon bond forming reaction was studied.
		Ene Reactions of a Chiral Glyoxylate Ester", Whitesell, J. K.; Bhattacharya, A.; Aguilar, D. A.; and Henke, K.,
		"Asymmetric Induction in the Ene Reaction of a Glyoxylate Ester of S-Phenyl Menthol", Whitesell, J. Bhattacharya, A.; Chen, H. H.; Deyo, D.; James, D.; and Liu, C. Tetrahedron, 42 (11), 2993-3001 (1986).
	www.tamuk.edu /chemistry/faculty/apuresume.html (659 words)

	Prins Reaction (Site not responding. Last check: 2007-11-03)
		The Prins-Reaction is the acid-catalyzed of addition aldehydes to alkenes, and gives different products depending on the reaction conditions.
		It can be thought of conceptually as the addition of the elements of the gem-diol carbonyl hydrate of the aldehyde across the double bond.
		Although the mechanism is different, a Prins allylic alcohol product is equivalent to the result of an Ene Reaction.
	www.organic-chemistry.org /namedreactions/prins-reaction.shtm (107 words)

	Lund University, Doctoral Dissertation (Site not responding. Last check: 2007-11-03)
		This thesis describes an improvement of the glyoxylate ene reaction by using siamyl glyoxaylate and a development of the novel rearrangement of allyl benzyl ethers.
		During the work with the ene reaction it was found that the ene component underwent a rearrangement to give arylbutanals in moderate to good yields, when zeolite b was used as catalyst.
		The reaction was further developed and variation of the substitution pattern at the allylic and benzylic positions showed that the rearrangement was quite general.
	www.lub.lu.se /cgi-bin/show_diss.pl?db=global&fname=sci_103.html (439 words)

	Research
		In the last couple of years we have focused on the Pauson-Khand reaction, a cobalt-mediated [2+2+1] cocyclization of an alkene, an alkyne and carbon monoxide to a cyclopentenone.
		We are also interested in tandem or domino reactions employing different metal catalysts or combinations of Lewis acids and metal catalysts.
		16 and subsequent Lewis acid-catalyzed Diels-Alder reaction to the perhydroisoindoles
	www.uni-stuttgart.de /ochem/02/Research_e.htm (385 words)

	Chapter 5 - Organic Reactions
		Perform single-point energy calculations using the B3LYP/6-31G* density functional model on both 1-pentene and on the ene reaction transition state (using the 3-21G geometries).
		Obtain the activation energy (difference in total energies between 1-pentene and the ene reaction transition state).
		When completed, the results (a list of molecules) will be placed in a file "ene reaction 1-pentene_3-21G.IRC1".
	www.wavefun.com /software/spartan04_win/win_manual/Chapter5_5.html (220 words)

	Singlet Oxygen (Site not responding. Last check: 2007-11-03)
		There are also several chemical methods of generating singlet oxygen, most notably the reaction of hydrogen peroxide with hypochlorite.
		Singlet oxygen has a lifetime of under a second, but it is very much more reactive towards organic compounds than is triplet oxygen, reacting readily with alkenes (ene reaction to form allylic hydroperoxides), dienes (cycloaddition to form 1,2-dioxanes), electron-rich aromatic compounds, phosphines, sulfides and selenides (to form oxides).
		Note that the singlet oxygen ene reaction corresponds to an allylic oxidation with migration of the double bond, analogous to the sequence epoxidation, elimination.
	www.chem.wisc.edu /areas/reich/chem547/_chem547-redox{19}.htm (230 words)

	APURBA BHATTACHARYA
		Most organic reactions are performed in presence of organic solvents.
		A reaction, which is performed without addition of any solvent, has several advantages.
		reactions can be achieved by the use of both microwave as well as ultlasonication technology.
	www.tamuk.edu /chemistry/faculty/apurba_bhattacharya.htm (1526 words)

	Chapter 5 - Organic Reactions
		The proposed mechanism of the ene reaction involves simultaneous transfer of a hydrogen atom along with CC bond cleavage.
		Here, you will obtain the transition state for the ene reaction of 1-pentene from 3-21G Hartree Fock calculations, and you will examine the reaction coordinate for evidence that hydrogen transfer and CC bond breaking occur in concert.
		Bring up the entry model kit and build 1-pentene in a conformation in which one of the terminal hydrogens on the ethyl group is "poised" to transfer to the terminal methylene group.
	www.wavefun.com /software/spartan04_win/win_manual/Chapter5_2.html (198 words)

	Bioline International Official Site (site up-dated regularly)
		This necessitates the need to understand the modes of photo-oxidation reactions of hydrocarbons structurally related to constituents of crude oils and their processed fractions.(Anderson, 1992).The photo-oxidation reaction of 6-methyl-1-phenylcyclohexene showed that the tri-substituted cycloalkene reacted in the 'ene' and [2 + 4] cycloaddition modes to give hydroperoxide and bis(endoperoxide) products respectively (Fekarurhobo, 1997)..
		The formation of the hydroperoxides (2) and (3) in the 'ene' reaction of (1) is explainable on the basis of abstractions of the axial H
		The photo-oxidation reaction of (1) differs remarkably from that of 6-methyl-1-phenylcyclohexene (Fekarurhobo, 1997) in that no bis(endoperoxide) was formed in the present reaction. Bis(endoperoxides) are formed from cisoid 1,3-dienes in a concerted mechanism, which requires the coplanarity of the reacting olefinic bonds (Wasserman, 1979).
	www.bioline.org.br /request?ja02029 (805 words)

	Brummond Research Group (Site not responding. Last check: 2007-11-03)
		A Rhodium(I)-Catalyzed Allenic Alder-ene Reaction for the Rapid and Stereoselective Assembly of Cross-Conjugated Trienes," K.M. Brummond; H. Chen; P. Sill, L. You, J. Am.
		A Silicon-Tethered Allenic Pauson-Khand Reaction," K.M. Brummond*; P.C. Sill, B. Rickards, S.J. Geib, Tetrahedron Lett., 2002, 43, 3735
		A Rapid Synthesis of Hydroxymethylacylfulvene (HMAF) Using the Allenic Pauson-Khand Reaction.
	www.pitt.edu /~kbrummon/pubs.html (519 words)

	PSU Chemistry \| Xumu Zhang (Site not responding. Last check: 2007-11-03)
		The focus of Zhang's research is to develop a useful chiral toolbox (n ligands) for strategically important asymmetric catalytic reactions (m reactions) by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts.
		The common feature of these ligands is that they contain rigid aromatic backbones or ring structures that could be used to restrict conformational flexibility of the ligands, and thus the efficiency of chiral transfer can be enhanced through the ligand rigidity.
		The following reactions have been studied: asymmetric hydrogenation of functionalized substrates such as N-acylaminoacrylic acids, enamides, enol acetates; asymmetric hydrogenation of simple olefins, ketones, and imines; and asymmetric carbon-carbon bond formation reactions.
	www.chem.psu.edu /profs/zhang.html (470 words)

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