The conformation of derivatives of O-aryllactic acid used as chiral reagents in structure determination. NMR and X-ray structure analysis of diastereoisomeric menthol esters

1993 ◽  
pp. 1113 ◽  
Author(s):  
Andreas Heumann
Keyword(s):  
Structure Analysis ◽  
Structure Determination ◽  
X Ray ◽  
Derivatives Of

Zur Struktur und Dotierung von Selenosilikaten: die Kristallstruktur von Er2SeSiO4 und Er3,75Ca0,25Se2,75Cl0,25Si2O7 Structure and Doping of Seleno Silicates: the Crystal Structures of Er2SeSiO4 and Er3,75Ca0,25Se2,75Cl0,25Si2O7

1994 ◽  
Vol 49 (6) ◽  
pp. 733-740 ◽  
Author(s):  
Klaus Stöwe
Keyword(s):  
Crystal Structures ◽  
Structure Analysis ◽  
Rare Earths ◽  
Structure Determination ◽  
Lattice Parameters ◽  
Energy Dispersive ◽  
Space Group ◽  
X Ray ◽  
By Products

Well-shaped brown and pink isometric crystals were obtained as by-products of the synthesis of erbium selenides from the elements in evacuated and sealed silica ampoules with graphite inlets. They could be identified as erbium seleno mono- and disilicates by energy dispersive X-ray fluorescence and X-ray structure determination. The monosilicate Er2SeSiO4 crystallizes isotypically to Nd2SeSiO4 in the space group Pbcm with the lattice parameters a = 600.2(2), b = 688.0(2), c = 1075.2(2) pm and represents the second known seleno inosilicate of the rare earths. From X-ray structure analysis an isotypic relation between the disilicate Er3,75Ca0,25Se2,75Cl0,25Si2O7 and the compound Sm4S3Si2O7 was found, the former crystallizing in the space group I41/amd with the lattice parameters a - 1177.7(2) and c = 1376.5(2) pm. The doping o f the sorosilicate with the elements Ca and Cl originated from contam inations in the graphit inlets used in the procedure

Neuartige Allylboran- und Allyldiboran(4)-Derivate / Novel Allylboran- and Allyldiboran(4) Derivatives

1990 ◽  
Vol 45 (7) ◽  
pp. 985-988 ◽  
Author(s):  
Gabriele Knörzer ◽  
Hermann Seyffer ◽  
Hans Pritzkow ◽  
Walter Siebert
Keyword(s):  
Structure Analysis ◽  
X Ray ◽  
Chloro Derivative ◽  
Chloro Derivatives ◽  
Derivatives Of

Allyldiboran(4) derivatives la—c are obtained from allylmagnesium chloride and chloro derivatives of diboran(4). la—c are air-sensitive liquids; heating of le did not yield a 2,3-dihydro-l,2-diborole derivative (B). Reaction between 1,1-bis(dichloroboryl)-3,3-dimethyl-butane (5) and H2C=C(CH2SnMe3)2 (4) leads to the heat-sensitive chloro derivative 2a, in which the chlorine is substituted by Me3SiNMe2 to give stable 1,3-bis-dimethylamino-5-methylene-2-neopentyl- 1,3-diborinane (2 b). 1,2-Bis(dichloroboryl)benzene and 4 yield the chloro derivative 3a, and its substitution with HN(i-Pr)2 leads to 1,4-bis(diisopropylamino)-2,3-benzo-6-methylene-1,4,5,7-tetrahydro-1,4-diborepine (3 b). The X-ray structure analysis reveals a folded tetrahydro-1,4-diborepine ring.

Tri-n-butyltin carboxylate derivatives of para-substituted phenyl-ethanoic acids: synthesis, characterization and X-ray structure determination

2004 ◽  
Vol 689 (21) ◽  
pp. 3301-3307 ◽  
Author(s):  
Luigi Angiolini ◽  
Daniele Caretti ◽  
Laura Mazzocchetti ◽  
Elisabetta Salatelli ◽  
Cristina Femoni
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Derivatives Of

X-ray crystal structure analysis of a bisepoxide derived from secologanin: the structure and absolute configuration

1983 ◽  
Vol 61 (2) ◽  
pp. 282-283 ◽  
Author(s):  
Stanley C. Nyburg ◽  
Pik Y. Siew ◽  
Gavin N. Saunders ◽  
John R. Purdy ◽  
Stewart McLean
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Dimethyl Acetal ◽  
Crystal Structure Analysis ◽  
Side Chain ◽  
Bench Mark ◽  
Chemical Transformations ◽  
X Ray ◽  
Derivatives Of

The structure and absolute configuration of a bisepoxide (2) produced by oxidation of tetraacetylsecologanin dimethyl acetal (1) with m-chloroperbenzoic acid have been established by X-ray crystal structure analysis. Epoxidation of the vinyl side chain is unexceptional; epoxidation of the β-alkoxyacrylate moiety is novel. This determination represents a valuable bench mark for configurational assignments, since the bisepoxide has been correlated by chemical transformations with a number of synthetic and naturally-occurring derivatives of secologanin.

Preparation of Carboranyl and Dodecaborate Derivatives of Coumarin

2007 ◽  
Vol 72 (12) ◽  
pp. 1740-1754 ◽  
Author(s):  
Eugen Justus ◽  
Dana T. Izteleuova ◽  
Alexander V. Kasantsev ◽  
Mendel M. Axartov ◽  
Enno Lork ◽  
...  
Keyword(s):  
Structure Analysis ◽  
The Other ◽  
Magnesium Salt ◽  
Ester Bond ◽  
Coumarin Derivatives ◽  
X Ray ◽  
Derivatives Of ◽  
Coumarin Ring

A series of derivatives of coumarin (2H-chromen-2-one) and 6,7-benzocoumarin (3H-benzo-[f]chromen-3-one) carrying the o-carborane, m-carborane, and dodecaborate clusters, has been obtained. X-ray structure analysis has been carried out for three of the products. The addition of o-carborane occurs in the 4-position of the coumarin ring, in a stereoselective way, independent of whether the cluster was reacted as the lithium or magnesium salt. m-Carborane gives two products, one being the result of 1,2-addition to an exocyclic ester bond and 1,4-addition to the coumarin system, the other resulting from 1,4-addition. The negatively charged dodecaborate derivatives obtained, link the cluster via oxygen or sulfur and an appropriate linker to a 7-hydroxy-substituted coumarin. For the coumarin derivatives, an o-carboranecarbonyl derivative could also be obtained.

Studies of Australian Soft Corals .XXXVI. The Isolation and Structure Determination of 11 Calamenene-Based Sesquiterpenes From Lemnalia-Cervicornis (Coelenterata, Octocorallia, Alcyonacea)

1986 ◽  
Vol 39 (1) ◽  
pp. 103 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
LM Engelhardt ◽  
DM Tapiolas ◽  
AH White
Keyword(s):  
Structure Determination ◽  
Soft Coral ◽  
Soft Corals ◽  
X Ray ◽  
Chemical Correlation ◽  
Derivatives Of ◽  
Absolute Stereochemistry

The soft coral Lemnalia cervicornis May 1898 has afforded 13 novel sesquiterpenoid metabolites. The majority were derivatives of calamenen-7-ol and the structures were deduced by 1H and 13C n.m.r . spectroscopy. Absolute stereochemistry of compounds (3)-(13) was determined by chemical correlation with 7-hydroxycalamenen-3-one (3) for which an X-ray structure determination of its 7-p-bromobenzoyl derivative is reported. Two minor metabolites (15) and (16) were not aromatic, but were structurally related to the algal metabolite zonarene (21) for which absolute stereochemistry was available.

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