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Topic: Endo isomer

	Copolymers of 5-norbornene 2,3-dicarboxylic anhydride and maleic anhydride - Patent 4126738
		The exo and endo adducts as well as mixtures thereof are capable of undergoing polymerization to yield these novel copolymers by the process of the present invention.
		An absorption peak at 730 cm.sup.-1, characteristic of unsaturated polymers derived from cyclopentene and cyclopentadiene and present in the spectra of the cyclic exo and endo adducts, cis-5-norbornene-2, 3-dicarboxylic anhydride, is virtually absent in the spectra of the copolymers of this invention, indicating the absence of any significant amount of unsaturation.
		C., i.e., temperatures where endo-exo isomerization of the adduct occurs and leads to the formation of polymers containing units derived from maleic anhydride, the endo adduct and the exo adduct.
	www.freepatentsonline.com /4126738.html (2377 words)

	Exo Selectivity
		The fact that they can not prove easily the synthesis of the endo isomer suggests that the selectivity can be found earlier in the reaction process.
		We can say that there is a stabilization due to this interaction, that is not in the endo isomer.
		We make the distinction in benzopyrrole between isomers with the H pointing toward the benzene ring.
	www.ch.ic.ac.uk /motm/porphyrins/P2.html (1165 words)

	Bicyclooctane and bicycloheptane derivatives - United States Patent 5,674,905
		The exo and endo regioisomers were separated by column chromatography (silica 30% ethyl acetate and 70% hexane) to give exo isomer (high R.sub.f) 6.05 g, and endo isomer (lower R.sub.f) 6.15 g.
		The compound was prepared essentially as in example 1 using the endo isomer (isolated in step a.) instead of the exo isomer as the substrate in step b.
		The anhydride was isolated as an inseparable mixture of endo and exo isomers (1.13 g, 79%).
	xrint.com /patents/us/5674905 (11884 words)

	(WO/2001/053269) ACID ADDITION SALTS OF IMIDAZOLIDINONES AS REACTION CATALYSTS (Site not responding. Last check: 2007-10-16)
		3 endo : exo, endo 93% ee, exo 93% ee.
		0 endo : exo, endo 90% ee, exo 86% ee.
		; endo 90% ee ; exo 86% ee.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/53269.010726&ELEMENT_SET=DECL (6565 words)

	ROMP Reactivity of endo- and exo-Dicyclopentadiene (Site not responding. Last check: 2007-10-16)
		The activation parameters for the ring-opening metathesis polymerization (ROMP) of endo- (1) and exo-dicyclopentadiene (2), endo-1,2-dihydrodicylopentadiene (3), and norbornene (4) in the presence of Grubbs' catalyst were determined using in situ NMR.
		The exo isomer of DCP was found to be more than an order of magnitude more reactive than the endo isomer.
		This interaction is shown to be predominantly entropic and is suspected to originate from an interaction of the penultimate repeat unit and the incoming monomer.
	pubs.acs.org /cgi-bin/abstract.cgi/mamobx/2002/35/i21/abs/ma0209489.html (172 words)

	Rearrangement
		These isomers are rapidly interconverted under the rearrangement conditions, indicating that the initial water loss is reversible; a result confirmed by isotopic oxygen exchange.
		It is reported that the symmetrically substituted isomeric diol (drawn in the shaded box) rearranges exclusively by a methyl shift, but the configuration of the starting material was not stated (two diastereomers are possible).
		These isomers were solvolyzed in hot acetic acid solution, buffered with sodium acetate, and the configurations of the resulting acetate esters were determined.
	www.cem.msu.edu /~reusch/VirtTxtJml/rearrang.htm (7059 words)

	E033: Troubles With Isomers Of (Isodicp)Ticl₃ (Site not responding. Last check: 2007-10-16)
		Some interesting problems have been encountered during the structure determinations of the diastereomeric endo and exo complexes of isodicyclopentadienyl titanium trichloride.
		The endo complex is in Pbcm with Z = 4 and contains a crystallographic mirror plane, while the exo complex is in Pca2
		During the synthesis of the endo isomer, an unexpected µ-oxotetramer was obtained: cyclotetrakis(µ-oxo-(endo-isodiCp)TiCl).This is a TLS twinned tetragonal structure in P4 /n with a = 16.331(1) and c = 7.498(1) Å.
	www.hwi.buffalo.edu /ACA/ACA97/abstracts/text/E033.html (237 words)

	Novel, Efficient, Palladium-Based System for the Polymerization of Norbornene Derivatives: Scope and Mechanism (Site not responding. Last check: 2007-10-16)
		The effect of coordinating solvents and the uptake of endo vs exo isomers for functionalized norbornenes was tested.
		Experiments show that (a) the endo isomer reacts more slowly than the exo isomer and (b) both isomers react much more slowly compared to norbornene derivatives lacking coordinating functionalities.
		A further reason for the diminution of activity of both the endo- and the exo-functionalized isomers is simply the coordination of the functionality.
	pubs.acs.org /cgi-bin/abstract.cgi/orgnd7/2001/20/i13/abs/om010232m.html (335 words)

	PM3 Calculations on a porphyrinic-host catalyzed intermolecular Diels-Alder reaction
		The barrier energy for the exo-reaction is lower than the endo by 3.16 Kcal/mol, suggesting that the normal endo specificity for the transition state model is not reproduced in this case.
		The results for catalyst 1 show that the complexed exo-adduct is more stable than the corresponding endo isomer, this stability being substantially enhanced by complexation within the host.
		This resulted to be an artifact of the geometry optimization and we have located a structure in which the adduct fits into the cavity and is lower in energy than the endo.
	www.ch.ic.ac.uk /ectoc/ectoc-3/pub/014 (533 words)

	Biotransformation of Nonionic X-Ray Contrast Agents In Vivo and In Vitro -- Jacobsen et al. 27 (10): 1205 -- Drug ...
		the iodixanol isomers (exo and endo) and with a mass increase
		The spectra of exo-iodixanol and M1 show a shift to longer wavelength of ~1 nm relative to the spectra of endo-iodixanol and M2; the maximum wavelengths of 245 nm (endo and M2) and 246 nm (exo and M1) are indicated (inset).
		The four metabolite peak groups (M1, M2, M3, and M4) and the exo- and endo-iodixanol isomers are indicated.
	dmd.aspetjournals.org /cgi/content/full/27/10/1205 (6644 words)

	BET2 Software - The identification of epimer alcohols
		exo - and endo - 5,10 - methylene - 10,11 - dihydro - 5H - dibenzo [a,d] cyclohepten - 11 - ols:
		The mass spectra of these substances (notes by isomer X and isomer Y) are similar, as the command "Correlated spectrum" of CSI-Diff-ms v1.2 illustrates:
		This wouldn't allowed a certain identification of two isomers structure, but a total 88.4% similarity indicate a sufficient difference for CSI-Diff-ms permitting to establish those two structures.
	www.bet2-soft.de /applications/app1.htm (462 words)

	[No title] (Site not responding. Last check: 2007-10-16)
		When its hydroxy group (O is red) is oxidized, camphor is produced.
		The isomer with an exo OH group is called isoborneol.
		When camphor is reduced with sodium borohydride, The major product is isoborneol, with an exo hydroxy group, because the hydride reagent approaches from the less hindered endo side of the molecule.
	www.nsm.du.edu /organic/organic2ed/fig28-3.html (112 words)

	(WO/2001/014374) PROCESSES FOR THE PREPRATION OF EXO- AND ENDO-INDOLOTROPANES (Site not responding. Last check: 2007-10-16)
		Standard literature methodology for the preparation of 3-tropanyl indoles is non- stereoselective, giving a mixture of isomers which may be difficult, if not impossible to separate.
		We have now discovered methodology for stereoselectively preparing both endo-indolotropane isomers and exo-indolotropane isomers which may be useful intermediates in the synthesis of pharmacologically active compounds.
		The stereochemistry was assigned by examination of the coupling constants of the signal at 8 3.43, in addition to nOe studies.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/14374.010301&ELEMENT_SET=DECL (1872 words)

	GR/M54209/01 (Site not responding. Last check: 2007-10-16)
		These showed that in the endo:endo isomer, as in 15, the fold angle between the two 3-membered rings is ca.
		Given the success had in the preparation of main group-phosphavinyl complexes many attempts were made to prepare similar transition metal complexes via the reaction of 6, R = Cy, with transition metal halide complexes.
		Not a great deal of success was had, however, as the variable accessible oxidation states of transition metals often led to oxidative coupling reactions of the phosphavinyl fragment to give 15 or its valence isomer, 20.
	www.cf.ac.uk /chemy/staff/jones/grm54209/grm54209.html (1934 words)

	Synthesis of enantiopure 7-aminobicyclo[3.2.0]hept-2-en-6-ol; a potential N-O chelating ligand for enantioselective ...
		which reacted with cyclopentadiene, affording the adduct 3 in 75 % yield: NMR spectroscopy revealed that the exo isomer was present as a very minor impurity(< 5 %).
		H NMR NOE experiments and X-ray crystallography confirmed the endo isomer as the major product.
		The preference for the formation of the less stable endo isomer is diagnostic evidence of the [
	www.organic-chemistry.org /abstracts/literature/523.shtm (511 words)

	ACE REACTION WITH PAHs
		In those reactions where two isomers (exo- and endo-) were obtained (Scheme 2), the endo- adduct was always the dominant product.
		After the initial 1,3-dipolar formation of the 1:1 endo- adduct 15, it was found that further reaction of epoxide 5 with 15 produced 2:1 adducts 20 and 21 (Scheme 3).
		In the initial experiment with an excess of anthracene, small amounts of 2:1 adducts were detected, while experiments with epoxide in excess (up to 4:1 ratio) gave larger quantities of these 2:1 adducts.
	www.mdpi.org /ecsoc/ecsoc-7/papers/a009/a009.htm (2258 words)

	e-Polymers (Site not responding. Last check: 2007-10-16)
		It was found that the exo isomer is much more reactive than the endo diastereoisomer.
		In refluxing CHCl3 using [NAZ]/[Ru] = 100, the exo isomer gave a polymer with a 83% yield and
		The azlactone ring survived intact during the polymerization and may be used for further reactions with nucleophiles, allowing polymer analogous reactions and crosslinking.
	www.e-polymers.org /abstract_shw.cfm?Abstract_id=154 (146 words)

	VOH // Questions and Answers for 130A Lab
		Professor, In the key to the problems from week 3, the answer to # 1-b is written as the endo isomer and the reason is that the exo apprach is less sterically hindered.
		There is a two-carbon bridge on the side of the endo approach.
		The best way to explain the experimental results (that is, the exo produst for the camphor i s favored and for 2-Norboranone the endo is favored) is to look at models.
	voh.chem.ucla.edu /vohtar/winter01/130AL/qa.html (4240 words)

	syn/anti elim (Site not responding. Last check: 2007-10-16)
		We use this compound to explain why a periplanar configuration of atoms is required.
		The endo-cis isomer (left) undergoes elimination very slowly.
		Hydrogen and chlorine are in a trans relation, but the dihedral angle is 126°, far from periplanar.
	www.cmbi.kun.nl /~borkent/wetche/diclelim.html (370 words)

	Pericyclic Reactions: Cycloadditions and Diels-Alder Reaction - ChemgaPedia (Site not responding. Last check: 2007-10-16)
		With normal priority: pericyclic reaction, exo, endo, facial selectivity, regioselectivity
		endo isomer transformed into the more stable exo isomer.
		endo rule" applies to Diels-Alder reactions but it is less adhered to than facial selectivity.
	www.chemgapedia.de /vsengine/printvlu/vsc/en/ch/2/vlu/pericyclische_reaktionen/diels_alder.vlu.html (1715 words)

	Process of enhancing the aroma of a soap with norbornane derivatives - Patent 4126571
		Fenchol made by reduction of Fenchone from Cedarleaf oil is usually a mixture of several isomers, including the crystalline alpha-isomers.
		Unless otherwise specified, representations herein of carbon-carbon double bonds are intended to indicate a "cis" isomer, a "trans" isomer, or a mixture of "cis" and "trans" isomers with respect to that carbon-carbon double bond.
		If the starting material is "endo" 2-acetyl-3,3-dimethyl-5-norbornene, then the final product will also be an "endo" isomer.
	www.freepatentsonline.com /4126571.html (13220 words)

	Endo Rule
		This is the thermodynamically less stable endo isomer, shown below for the Diles-Alder reaction between cyclopentadiene and maleic anhydride.
		The outcome of a Diels-Alder reaction involving non-cyclic components also often obeys the endo rule.
		As the reaction forms four new stereocentres it is helpful to follow this step-by-step guide to predicting the relative stereochemistry of the endo rule product (see also Warren and Wothers, p 913).
	users.ox.ac.uk /~mwalter/web_05/year3/peri_I/endo_rule.shtml (96 words)

	Dr
		Recognize the meaning of the words endo (isomer), exo(isomer), adduct, monomer, dimer, cracking, and dimerization.
		Write a mechanism for the Diels-Alder reaction of cyclopentadiene and maleic anhydride.
		Recognize the type of mechanism in the nitration reaction (i.e electrophilic aromatic substitution).
	www.gpc.edu /~jpoteat/2642lLabFinalExamReview.htm (695 words)

	Estrogenic Effects of Organochlorine Pesticides on Uterine Leiomyoma Cells in Vitro -- Hodges et al. 54 (2): 355 -- ...
		The antiestrogen ICI 182,780 dampens the proliferative effect of HPTE, KPN, and Endo-
		Ethanol was used as the vehicle control for E2, ICI 182,780, Endo-
		DMSO was used as the vehicle control for MXC, HPTE, KPN, TXP, and DLN.
	toxsci.oxfordjournals.org /cgi/content/full/54/2/355 (5465 words)

	Rare nucleotides (Site not responding. Last check: 2007-10-16)
		Adenosine- 2', 3'- cyclic monophosphorothioate, exo / Sp- isomer (Sp-2',3'-cAMPS)
		8- Bromoadenosine- 2', 3'- cyclic monophosphorothioate, Sp- / exo- isomer (exo-2',3'-8-Br-cAMPS)
		Please inquire regarding special structures not listed here.
	www.biolog.de /miscella.html (229 words)

	Quiz (Site not responding. Last check: 2007-10-16)
		Explanation: See the introduction in the lab manual and your lab text.
		Answer: a-Explanation: In a Diels Alder reaction, the endo product is usually formed first, because it is the result of favorable p orbital overlap as the two reactant molecules come together.
		However, under reversible conditions, the exo product will predominate, because even though it is not formed as quickly, it is more stable, has less steric strain, than the endo isomer.
	orgchem.colorado.edu /labquizzes/dielsalder/dielsalderquizans.html (414 words)

	Diels-Alder Reaction
		First, since the reaction involves the precise overlap of the 'p' orbitals in the HOMO and the LUMO of the reactants, the product always shows 'syn' addition.
		If a bicyclic product is formed, the 'endo' isomer is formed in preference to the 'exo' isomer (you may want to use your molecular models to convince yourself of this).
		In addition, the diene must adopt an 's-cis' conformation for the reaction to proceed.
	www2.volstate.edu /CHEM/2020/Labs/Diels_Alder.htm (920 words)

	Mu-Class GSTs Are Responsible for Aflatoxin B1-8,9-Epoxide-Conjugating Activity in the Nonhuman Primate Macaca ...
		were used to generate a racemic mixture of endo and exo AFBO
		activity of both endo and exo AFBO were determined in triplicate,
		the exo-AFBO isomer reacts with DNA (Iyer et al.
	toxsci.oxfordjournals.org /cgi/content/full/56/1/26 (6328 words)

	16,17-Dihydro Gibberellin A5 Competitively Inhibits a Recombinant Arabidopsis GA 3{beta}-Hydroxylase Encoded by the GA4 ...
		GAs, however, was dihydro GA, where both the endo- and exo-isomers
		It is thus possible that a wide range of GA or GA derivatives (Table I) will function as competitive substrate
		in efficacy between the two exocyclic isomers (Table I).
	www.plantphysiol.org /cgi/content/full/135/2/1000 (4256 words)

	Kein Folientitel (Site not responding. Last check: 2007-10-16)
		chemistry, to give the endo isomer of 4.54.
		Diels-Alder reactions have also been accelerated inside
		reversed to give mainly the endo adduct if a smaller
	www.organik.uni-erlangen.de /hirsch/vorlesung/supramolecular/04Templates/04Templates-Dateien/slide0134.html (102 words)

	ORGANIC CHEMISTRY II - Old Exam #2 (Site not responding. Last check: 2007-10-16)
		Two isomers of bicyclopentadiene can be formed when this reaction occurs; however, the endo isomer predominates.
		Draw the structures of both of the endo and exo bicyclopentadiene products formed by the Diels-Alder reaction of 1,3-cyclopentadiene with itself.
		Give a common or IUPAC name for each of the following structures: (18 points)
	www.sbuniv.edu /~ggray/CHE3314/oexam2.html (302 words)

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