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Topic: Hemiaminal

In the News (Sun 29 Nov 09)

Northern Trust

Marvin Harrison

Peter Chernin

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Match Play

Penelope Cruz

Mickey Rourke

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Danny Boyle

Hugh Jackman

	Marisha Banerji (Site not responding. Last check: 2007-11-05)
		Hemiaminals are structures containing a carbon attached to a hydroxyl group and an amine.
		Thus, hemiaminals can potentially inhibit serine proteases, which are enzymes that catalyze the hydrolysis of peptide bonds by a nucleophilic attack on the targeted bond by a serine.
		The focus of this summer's project is the synthesis of a key intermediate in the formation of a target hemiaminal.
	www.brynmawr.edu /scienceresearch/MarishaBanerji.html (176 words)

	Total syntheses of (+)-zampanolide and (+)-dactylolide
		Chapter 1 of this dissertation describes synthetic efforts culminating in the first total synthesis and complete stereochemical assignment of (+)-zampanolide (3), the non-naturally-occurring antipode of a potent cytotoxic marine macrolide.
		Retrosynthetically, initial disconnections of zampanolide at the amide and N-acyl hemiaminal linkages gave rise to hexa-2(Z),4(E)-dienoic acid chloride (fragment D) and α-alkoxy acid 135.
		Since the final step in the synthesis of (+)-zampanolide (3) inevitably led to erosion of stereogenicity at C(20), we were unable to assign the relative and absolute configuration at that center with certainty.
	repository.upenn.edu /dissertations/AAI3043946 (369 words)

	Reductive Amination Review
		The first step is a nucleophilic addition to the carbonyl group followed by a rapid proton transfer.
		The resulting product, a hemiaminal, also sometimes called a carbinolamine, is generally unstable and cannot be isolated.
		A second reaction occurs in which water is eliminated from the hemiaminal and imine is formed.
	www.erowid.org /archive/rhodium/chemistry/reductive.amination.html (2294 words)

	A post-Amadori inhibitor pyridoxamine also inhibits chemical modification of proteins by scavenging carbonyl ... (Site not responding. Last check: 2007-11-05)
		We studied the reaction of carbonyl compounds glyoxal (GO) and glycolaldehyde (GLA) with pyridoxamine (PM), a potent post-Amadori inhibitor of AGE formation in vitro and of development of renal and retinal pathology in diabetic animals.
		PM reacted rapidly with GO and GLA in neutral, aqueous buffer, forming a Schiff base intermediate that cyclized to a hemiaminal adduct by intramolecular reaction with the phenolic hydroxyl group of PM.
		This bicyclic intermediate dimerized to form a five-ring compound with a central piperazine ring, which was characterized by electrospray ionization-liquid chromatography/mass spectrometry, NMR, and x-ray crystallography.
	www.arclab.org /medlineupdates/abstract_11729198.html (272 words)

	P047 OXIDATION HYDROXYALKYLTRIAZOLIDINONES
		The first one forms the products via a Grob type fragmentation, the other one involves the valence tautomeric equilibrium with a zwitterionic species (4) which rearranges to the according triazolinone (5).
		This hemiaminal eliminates the former hydroxyalkyl substituent as a carbonyl compound to form (6).
		The position of ring fusion (ring position 4 rather than position 1) is not indicative of any suggested reaction pathway (compare different possible REACTION PATHWAYS FOR THIS TYPE OF OXIDATION), since there may be equilibration of hemiaminals after the reaction proper.
	www.ch.ic.ac.uk /ectoc/echet98/pub/047/punkt5.html (380 words)

	L-743,872, a novel antifungal lipopeptide: synthesis and structure-activity relationships of new aza-substituted ...
		L-733,560 incorporates a hemiaminal aminoethyl ether which was found essential for potent Aspergillus activity.
		Further modification at the hemiaminal utilizing novel methodology enabling the regioselective introduction of nitrogen nucleophiles under mild conditions will be described.
		A series of aza-substituted pneumocandins has been prepared and their beta-1,3-glucan IC(50)'s determined in a Candida albicans membrane assay.
	www.aegis.com /aidsline/1998/apr/m9841225.html (338 words)

	Science Day 2005 (Site not responding. Last check: 2007-11-05)
		In addition, this unique 20-membered macrolide has a high degree of unsaturation and an uncommon N-acyl hemiaminal side chain.
		The Porco group has initiated studies on the synthesis of (-)-zampanolide and initially focused on the synthesis of the N-acyl hemiaminal subunit.
		This poster will describe the synthesis of intermediates for the zampanolide core structure employing an intramolecular silyl modified Sukurai (ISMS) reaction for the construction of the exo-methylene pyran ring and a Heck reaction for the northern diene fragment.
	www.bu.edu /phpbin/scienceday/judges/abstract.php?id=351 (157 words)

	whistling in the wind
		In an unguided scenario where all aldehydes are created equal, the library would look something like this.
		Such a library was observed in a two step sequence where the authours treated the amino scaffold (two amine reacting centers) with a mixture of aldehydes (5 different aldehydes) generating either the imine or hemiaminal, followed by a reduction step using tetrabutylammonium cyanoborohydride (TBC) giving a HPLC-MS ready mixture of substituted amines.
		While the first four were identified from the DCC experiment, the last one while beng a potential library member, was not.
	sanjayat.wordpress.com (1916 words)

	Organic and Biomolecular Chemistry Articles (Site not responding. Last check: 2007-11-05)
		For cyclic ethers the hemiaminal products are generally stable and can be isolated pure.
		For acyclic ethers, the hemiaminal products, as expected, fragment with elimination of alcohol to yield imines.
		When activation of benzylic positions is remote through a conjugated system, stable benzylamine derivatives are isolated.
	www.rsc.org /Publishing/Journals/OB/article.asp?doi=b410883c (152 words)

	Application of the Meisenheimer rearrangement to the synthesis of hydroxylated tropane alkaloid derivatives
		Recently, there has been considerable interest shown in the newly discovered polyhydroxylated nortropane alkaloids known as the calystegins
		they are the only known nortropane and tropane alkaloids to possess a hemiaminal functionality.
		Our aim was to investigate a Meisenheimer rearrangement approach to the basic bridgehead hydroxylated skeleton present in these alkaloids based on an advanced alkaloid starting material.
	www.ch.ic.ac.uk /ectoc/echet96/papers/083 (115 words)

	CSIRO PUBLISHING - Australian Journal of Chemistry (Site not responding. Last check: 2007-11-05)
		Visit our Most Read page regularly to keep up-to-date with the most downloaded papers in this journal.
		Cyclic hemiaminal formation in solid X-unsubstituted azole aldehydes seems to be a general phenomenon when stabilization factors and position of substitution are favourable.
		In purine-8- carbaldehyde the hemiaminal may be accompanied by the aldehyde hydrate.
	www.publish.csiro.au /nid/51/paper/CH9712389.htm (131 words)

	Molecule of the Month August 2003 (Site not responding. Last check: 2007-11-05)
		Dihydroxyacetone (Dha) in hemiaminal linkage to the active site of dihydroxyacetone kinase (Swiss-Prot P76015).
		The hemiaminal is formed between the carbonyl carbon of Dha and the imidazole nitrogen of histidin-230 (HOCH
		Dha kinase can mop up microM concentrations of potentially toxic Dha in the presence of glycerol, a compatible solute which may be produced to high concentrations under salt and cold stress.
	dcbwww.unibe.ch /dcbneu/mom/mom14.html (100 words)

	Hydroxyalkyl Complexes and Hemiaminal Formation in the Reaction of o-Diphenylphosphinobenzaldehyde with Rhodium(I) ...
		Hydroxyalkyl Complexes and Hemiaminal Formation in the Reaction of o-Diphenylphosphinobenzaldehyde with Rhodium(I) Dihydrazone Complexes
		The complexes have been fully characterized, and X-ray diffraction structures of both of them are reported.
		Some intermediates in the competitive reactions have been spectroscopically characterized, and the transformation of the hemiaminal group into imine to give a PaNN ligand in the complex [Rh(H)(PCO)(Pabdh)]
	pubs.acs.org /cgi-bin/abstract.cgi/orgnd7/2000/19/i25/abs/om0006413.html (206 words)

	Hemiaminal - Wikipedia, the free encyclopedia
		A hemiaminal is a functional group or type of chemical compound that has a hydroxyl group and an amine attached to the same carbon atom: -C(OH)(NR R can be hydrogen or an alkyl group.
		An aminal or aminoacetal is a functional group or type of chemical compound that has two amine groups attached to the same carbon atom: -C(NR Again R can be hydrogen or an alkyl group.
		This page was last modified 16:18, 16 November 2006.
	en.wikipedia.org /wiki/Hemiaminal (139 words)

	May 6, 2002 Heart Cut (Site not responding. Last check: 2007-11-05)
		(Vitride) in aqueous glyme to the hemiaminal, followed by a portionwise addition of 60 equiv of LiBH
		A more selective approach uses a stepwise method starting with activation of the secondary amide as a urethane, followed by reduction to the hemiaminal and then to a methylene group.
		The first-generation process used 9-fluorenylmethoxycarbonyl (Fmoc) as the protecting–activating group, but this was soon replaced by the more affordable ethyl carbamate.
	www.acs.org /portal/a/c/s/1/acsdisplay.html?DOC=heartcut\archive\0506_heartcut.html (1107 words)

	Studies Toward the Synthesis of (-)-Zampanolide: Preparation of N-Acyl Hemiaminal Model Systems (Site not responding. Last check: 2007-11-05)
		Studies Toward the Synthesis of (-)-Zampanolide: Preparation of N-Acyl Hemiaminal Model Systems
		Synthesis of N-acyl hemiaminal model systems related to the side chain of the antitumor natural product zampanolide is reported.
		Evidence for stabilization of the N-acyl hemiaminal moiety in model compounds by an intramolecular hydrogen-bonding network is described.
	pubs.acs.org /cgi-bin/jtext?orlef7/4/i06/abs/ol025558l (120 words)

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