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Topic: Diastereoselectivity

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	Assymetric Induction
		BH, the diastereoselectivity is reversed, with isomer B being formed in 82% de.
		Its use in the reduction of 2,6-dimethyl-5-hydroxy-3-heptanone produces excellent diastereoselectivity, as a consequence of the intramolecular hydride transfer intermediate drawn in the right green shaded box (the bulky R substituent prefers to occupy an equatorial-like position).
		The increased diastereoselectivity of the Mukaiyama aldol reaction is noteworthy (de is 92 versus 56 for the analogous case in equation 1), and reflects the open transition state adopted by this reaction.
	www.cem.msu.edu /~reusch/VirtualText/sterslct.htm (8654 words)

	Stereoselective Additions To Alpha-Beta-Epoxyaldehydes
		The observation of any useful level of diastereoselectivity in the addition of simple nucleophiles to trans-substituted alpha-beta-epoxyaldehydes was unexpected, given the lack of diastereoselectivity found when a C-substituent replaces the silyl group.
		Nevertheless, the sense of the diastereoselectivity observed in additions to 1 and 2 is consistent with a `non-chelation' model, similar to the working hypothesis in our group used to account for the results from cis-alpha-beta-epoxyaldehydes.
		It appears that the preceding modelling and results from measurements in the solid state are not inconsistent with the suggestion outlined in Figure 3 that dipole-dipole repulsion is a significant factor in determining the minimum energy conformation of alpha-beta-epoxyaldehydes of this type.
	www.ch.ic.ac.uk /ectoc/papers/25/gp2text.html (1090 words)

	Diastereoselectivity in Gas-Phase Hydride Reduction Reactions of Ketones
		The intrinsic diastereoselectivity of the reduction of a series of cyclic ketones by pentacoordinate silicon hydride ions was investigated in the gas phase with the use of the flowing afterglow-triple quadrupole technique.
		The trend observed for the reduction diastereoselectivity of compounds 1-4 and 6 matches their condensed-phase behavior; i.e., the percent axial reduction is reduced when steric hindrance of the ketones is increased (1, 99 ± 3%; 2, 68 ± 5; 3, 9 ± 3%).
		regarding the diastereoselectivity of the reduction of 5 and 6 in the gas phase were confirmed, i.e., a preferred equatorial approach of the hydride reducing agent.
	pubs.acs.org /cgi-bin/abstract.cgi/jacsat/1999/121/i30/abs/ja9910053.html (351 words)

	Various aspects of double asymmetric consecutive catalytic reactions (Site not responding. Last check: 2007-10-11)
		The diastereoselectivity of the double asymmetric reaction is directly related to the inherent enantioselectivity of the catalyst.
		One application that we are currently exploring, is the possiblity to use the diastereoselectivity of the tandem asymmetric reactions for the evaluation of a racemic catalyst.
		The general equations relating diastereoselectivity and enantioselectivity at the first step (and then to a similar monofunctional substrate) remain valid if it is the same enantiomer of the catalyst which will act two times on the same substrate molecule.
	chem-faculty.ucsd.edu /siegel/orgchem/KaganAbstract2002.htm (360 words)

	Organic and Biomolecular Chemistry Articles
		Highly diastereoselective 1,3-dipolar cycloaddition reactions of trans-2-methylene-1,3-dithiolane 1,3-dioxide with 3-oxidopyridinium and 3-oxidopyrylium betaines: a route to the tropane skeleton
		A 2.3 : 1 mixture of regioisomers was formed with all of the 3-oxidopyridinium betaines but the ratio was found to change over prolonged periods of time due to reversibility of the minor regioisomer.
		Improved regioselectivity (8 : 1) and again high diastereoselectivity were observed with the betaine having an additional substituent at the 2-position, but with betaines having a substituent in the 6-position although high regioselectivity was observed (9.9 : 1), the major isomer was formed with low diastereoselectivity (5.5 : 4.4).
	www.rsc.org /publishing/journals/OB/article.asp?doi=b302834h (211 words)

	Computational studies on diastereo- and enantio-selectivities of allylmetalation of cyclopropenone acetals--
		The reaction of substituted allylic zinc reagents 9, 10 and 11 were thus examined in the presence of anionic bis-oxazoline ligand (2a or 2c) as shown in eqn.
		As summarized in Table 1, the diastereoselectivity for crotylzinc reagent 9, cinnamyl reagent 10 and perhydrocinnamyl reagent 11 was moderate (72:28, 73:27 and 83:17, respectively) and when the anionic bis-oxazoline ligands 2a and 2c was used.
		The enantiomeric selectivity and relative diastereoselectivity expected from the calculated difference of heat of formation are 94:6 and 92:8, respectively.
	www.ch.ic.ac.uk /ectoc/echet96/papers/071 (2404 words)

	The Faller Lab, Department of Chemistry, Yale University
		Diastereoselectivity in Chiral Ruthenium Complexes of Chiraphos Monoxide Ligands: Epimerization, Quasiracemates and Lewis Acid Catalysis, J.W. Faller, X.
		Synthesis, Characterization, Diastereoselectivity and Catalytic Activity of Complexes of Ruthenium with BINAP Monoxide.
		Diastereoselectivity in Chiral Osmium Complexes of a Bidentate Bisphosphine Monoxide Ligand, J.W. Faller, Jonathan Parr, Organometallics, 2000, 19, 3556-3561.
	jaxindy.chem.yale.edu (1388 words)

	Steric and Electronic Influences on the Diastereoselectivity of the Rh2(OAc)4-Catalyzed C-H Insertion in Chiral Ester ...
		The type and nature of the N-substituent in 10 or ent-10 was found to govern the diastereoselectivity of the reaction.
		Specifically, electron-donating substituents were found to markedly attenuate the diastereoselectivity of the reaction.
		The diastereoselectivity of the reaction ranged from moderate to high (37-98%).
	pubs.acs.org /cgi-bin/abstract.cgi/joceah/1998/63/i13/abs/jo971540q.html (263 words)

	Development and application of the lanthanide-mediated hydroamination reaction toward natural products
		A methyl group was installed at diverse positions in the substrate to determine the substitution pattern that would provide the greatest diastereoselectivity.
		It was found that substrates containing a methyl group α or β to the nitrogen provided the highest diastereoselectivity (>20:1) for the formation of quinolizidines and indolizidines.
		It was found that the benzo[a]quinolizine and the pyrido[2,1,a]isoindolizine ring systems formed with the highest diastereoselectivity (>20:1), regardless of the electronic characteristics of the aromatic ring.
	repository.upenn.edu /dissertations/AAI3095926 (384 words)

	Publications avec abstracts
		The chemoselectivity of PtxSny/SiO2 catalysts increased from 52 to 100%.
		This inverse tendency of chemo- and diastereoselectivity upon the addn.
		of tin that is added, controls the chemo- and diastereoselectivity via the coordination mode of the chiral cetaloxopromegestone.
	www.cpe.fr /lcoms/bayard/pub_ab.htm (2786 words)

	Glen P. Miller Research (Site not responding. Last check: 2007-10-11)
		The thermal instability of these compounds and the lack of cis diastereoselectivity is the addition are both attributed to the large spacing between [60]fullerene moieties.
		Thus, we devised a one-pot, diastereoselective synthesis of the cis,cis-tris[60]fullerene adduct of 6,8,15,17-tetraphenylheptacene, 7, starting from [60]fullerene and 5,7,9,14,16,18-hexahydro-6,8,15,17- tetraphenylheptacene, 8.
		The reaction proceeds in a highly diastereoselective fashion and in 75% crude yield.
	www.unh.edu /chemistry/gpmres.html (700 words)

	Synthesis of Dihydronaphthalenes via Aryne Diels-Alder Reactions: Scope and Diastereoselectivity.
		These give useful cis-substituted dihydronaphthalene building blocks in good yield which are not easily accessible via other means, as demonstrated in the synthesis of sertraline.
		The first asymmetric aryne cycloaddition with an acyclic diene is also reported, giving excellent diastereoselectivities with Oppolzer’s sultam as a chiral auxiliary.
		This article was last updated on Friday, 28th October 2005 at 1:05 am and is filed in the Sertraline section.
	counsellingresource.com /medications-research/2005/10/28/synthesis-of-dihydronaphthalenes-via-aryne-diels-alder-reactions-scope-and-diastereoselectivity (288 words)

	Felkin-Anh Stereoselectivity in Cycloadditions of Acetylketene: Evidence for a Concerted, Pseudopericyclic Pathway (Site not responding. Last check: 2007-10-11)
		While diastereoselectivity appeared to improve with larger R-groups, the overall yield of the reaction was decreased.
		-chiral carbon center was seen to have an affect on diastereoselectivity.
		This experimental data was used, along with molecular modeling, to determine the reaction pathway.
	www.che.uc.edu /chem761/Presentations/Summary4.htm (381 words)

	JCE 2006 (83) 101 [Jan] Diastereoselectivity in the Reduction of α-Hydroxyketones. An Experiment for the ...
		JCE 2006 (83) 101 [Jan] Diastereoselectivity in the Reduction of α-Hydroxyketones.
		To prepare our chemistry majors for the inquiry-based, research-like experiments in the integrated laboratories we introduced several experiments into the second-semester chemistry-major organic laboratory designed to give the students the required laboratory expertise to be successful in the integrated laboratories.
		A research type, inquiry-based project is described where students synthesize racemic α–hydroxyketones using umpolung, a polarity-reversal approach, investigate chelating versus non-chelating reducing agents, and finally determine the diastereoselectivity of these reducing processes by NMR spectroscopy.
	jchemed.chem.wisc.edu /Journal/Issues/2006/Jan/abs101.html (325 words)

	Novel Substituted Sodium Borohydride Reagents Leading to Diastereoselective Reductive Amination (Site not responding. Last check: 2007-10-11)
		Abbott Laboratories, North Chicago, IL High diastereoselectivity was desired for a key reductive amination step towards the synthesis of a novel clinical candidate.
		Conventional reducing agents and conditions led to poor diastereoselectivity or the formation of undesirable side products.
		A series of novel sterically hindered sodium borohydride reagents were developed that afforded the desired substituted amine intermediate with >80% diastereoselectivity under moderate conditions.
	acs.confex.com /acs/36glrm/techprogram/P7623.HTM (166 words)

	JCE 2001 (78) 531 [Apr] Diastereoselective Synthesis of (+/-)-1,2-Diphenyl-1,2-propanediol. A Discovery-Based Grignard ...
		JCE 2001 (78) 531 [Apr] Diastereoselective Synthesis of (+/-)-1,2-Diphenyl-1,2-propanediol.
		We have developed an undergraduate organic laboratory experiment that probes the diastereoselectivity of the reaction between a Grignard reagent and a common, inexpensive
		Since the mp ranges of the two possible diol diastereomers differ by 10 °C, the reaction's diastereoselectivity can be established by mp determination alone, and it can be rationalized by the preferential addition of MeMgI to the least sterically hindered face of the carbonyl group in a rigid, five-membered cyclic intermediate (the "Cram chelate model").
	jchemed.chem.wisc.edu /Journal/Issues/2001/Apr/abs531.html (334 words)

	Virtually complete control of simple and face diastereoselectivity in the Michael addition reactions
		Virtually complete control of simple and face diastereoselectivity in the Michael addition reactions between achiral equivalents of a nucleophilic glycine and (S)- or (R)-3-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones: practical method for preparation of beta
		Thus, the chiral 4-phenyl-1,3-oxazolidin-2-one moiety was found to control efficiently both face diastereoselectivities of the glycine derived enolate and the C,C double bond of the Michael acceptor.
		Excellent chemical yields and diastereoselectivities, combined with the simplicity of the experimental procedures, render the present method of immediate use for preparing various 3-substituted pyroglutamic acids and related amino acids (glutamic acids, glutamines, prolines, etc.) available via conventional transformations of the former.
	www.findyourhope.com /Article/70011/Page_Article.aspx (152 words)

	Stanford University Stanford CA
		On the Nature of the Ion Pair as a Nucleophile in Pd Catalyzed Alkylations with Dienyl Carboxylates Trost, B.M.; Bunt, R.C. Tetrahedron Lett.
		Double Diastereoselectivity in Addition of Metallated Propionitrile to Enones Trost, B.M.; Florez, J.; Haller, K.J. Org.
		On the Question of a Dipole Effect on Diastereoselectivity of Olefin Addition Trost, B.M.; Lynch, J.; Renaut, P. Tetrahedron Lett.
	www.stanford.edu /group/bmtrost/1984.html (3233 words)

	[No title] (Site not responding. Last check: 2007-10-11)
		My present interest is to develop titanium-mediated, diastereoselective cyclization of vinyl-tethered imides.
		Towards this end we have developed excellent diastereoselective cyclization of vinyl-tethered imides.
		Some of the crystal structures of the cyclized compounds are shown below:
	www.chem.wayne.edu /~soumava/Page3.htm (72 words)

	[No title]
		Diastereoselective Route to Piperidine and Indolizidine Scaffolds From Enantiopure Vinylsulfinyl-Containing Amino Alcohols
		Diastereoselective Aldol Reactions of Furaldehyde Using a Chiral Boronate as Auxiliary: Application to the Synthesis of Enantiomerically Pure and Highly Functionalized 2,3-Disubstituted Furanyl Alcohols
		Diastereoselective Synthesis of α-Methylpyroglutamates from α,β-Didehydro α-Amino Acids
	www.wiley-vch.de /cgi-bin/search_key.pl?p=1&sf=key&a1=Diastereoselectivity (242 words)

	News & Features: Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose
		ISCID Forums » General » News & Features » Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose
		Topic: Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose
		Abstract: Nutrient uptake by a primitive cell would have been limited by the permeability characteristics of its membrane.
	www.iscid.org /boards/ubb-get_topic-f-1-t-000268.html (300 words)

	Synthesis of Tetrasubstituted Ozonides by the Griesbaum Coozonolysis Reaction: Diastereoselectivity and Functional ... (Site not responding. Last check: 2007-10-11)
		Synthesis of Tetrasubstituted Ozonides by the Griesbaum Coozonolysis Reaction: Diastereoselectivity and Functional Group Transformations by Post-Ozonolysis Reactions
		The diastereoselectivity of the Griesbaum coozonolysis reaction with O-methyl 2-adamantanone oxime and 4-substituted cyclohexanones reveals that the major tetrasubstituted ozonide isomers possess cis configurations, suggesting a preferred axial attack of the carbonyl oxide on the cyclohexanone dipolarophiles.
		These tetrasubstituted ozonides are quite stable to triphenylphosphine, borohydrides, hydrazine, alkyllithiums, Grignard reagents, mercaptides, and aqueous KOH as illustrated by a wide range of post-ozonolysis transformations (see article).
	www.organic-chemistry.org /abstracts/lit1/016.shtm (138 words)

	On 1,4-Diastereoselectivity in the Chiral Allylsilane (Site not responding. Last check: 2007-10-11)
		Received 10 April 1998; revised 18 May 1998; accepted 19 May 1998
		substituted aldehydes to afford the corresponding 1,4-syn-products with good diastereoselectivities.
		The best selectivities are observed when the reactions are carried out by transmetallation of allylsilane using Tin (IV) chloride in CH Cl
	pcserver.iqm.unicamp.br /~ldias/rev7.htm (75 words)

	Find in a Library: Organic reaction in water. Part 31: diastereoselectivity in Michael additions of thiophenol to nitro ...
		Find in a Library: Organic reaction in water.
		Part 31: diastereoselectivity in Michael additions of thiophenol to nitro olefins in aqueous media
		WorldCat is provided by OCLC Online Computer Library Center, Inc. on behalf of its member libraries.
	worldcatlibraries.org /wcpa/ow/4acdf551c56f7f35a19afeb4da09e526.html (77 words)

	[No title] (Site not responding. Last check: 2007-10-11)
		These will produce different regiochemistry in the product.
		Diastereoselectivity As before for the allylboranes this is controlled by the geometry of the boron enolate.
		E enolates give anti product whereas Z enolates give syn.
	www.chem.leeds.ac.uk /People/CMR/labstuff/litreviews/boronchemistry.doc (1355 words)

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