Absolute configuration at the chiral nitrogen atom in an optically active oxaziridine. X-Ray structure of (2S)-(–)-N-(R)-α-methyl-benzyldiphenyloxaziridine

1976 ◽  
pp. 60-61 ◽  
Author(s):  
Maria Bucciarelli ◽  
Irene Moretti ◽  
Giovanni Torre ◽  
Giovanni Dario Andreetti ◽  
Gabriele Bocelli ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Absolute Configuration ◽  
Optically Active ◽  
X Ray

Synthesis and resolution of an asymmetric arsonium cation. Crystal and molecular structures of (R)-Benzyl(methyl)(4-methylphenyl)(naphthalen-1-yl)- arsonium bromide and hexafluorophosphate

1984 ◽  
Vol 37 (6) ◽  
pp. 1171 ◽  
Author(s):  
DG Allen ◽  
CL Raston ◽  
BW Skelton ◽  
AH White ◽  
SB Wild
Keyword(s):  
Ion Exchange ◽  
Absolute Configuration ◽  
Optically Active ◽  
Molecular Structures ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Ion Exchange Column ◽  
Optically Pure

The (�)-benzyl(methyl)(4-methylphenyl)(naphthalen-1-yl)arsonium cation has been synthesized and subsequently resolved by fractional crystallization of monohydrogen [R-(R*,R*)]-2,3-bis(benzoyloxy)- butanedioate salts. The separated diastereoisomers were converted into the corresponding optically active arsonium bromides by ion-exchange column chromatography. The absolute configuration of the arsonium cation exhibiting a positive rotation at 589 nm (sodium D line) has been established as (R) by single-crystal X-ray analysis of both the bromide and hexafluorophosphate salts. The arsonium bromide with [α]D + 54.8�(c, 0.62 in CH2Cl2) crystallizes in the orthorhombic space group P212121 (D24, No.19) with a 22.472(8), b 15.724(7), c 12.585(5) � and U 4447(3) �3. The corresponding hexafluorophosphate with [α]D + 19.3� (c, 0.5 in CH2Cl2) crystallizes in the same space group with a 23.56(2), b 16.40(1), c 13.12(1) � and U 5067(6) � 3. Benzylidene transfer to benzaldehyde from the arsonium ylide derived from either of the arsonium salts produced optically pure (–)-(S)-methyl(4-methylphenyl)(naphthalen-1-yl)arsine, [α]D - 115.9� (c, 0.593 in CHCl3), and partly resolved [R-(R*,R*)]-2,3-diphenyloxiran.

(1S,7S)-7-Methyl-6,9-diazatricyclo[6,3,0,01,6]tridecane-5,10-dione, a tricyclic spirodilactam containing non-planar amide groups: Synthesis, NMR, crystal structure, absolute configuration, electronic and vibrational circular dichroism

1988 ◽  
Vol 53 (11) ◽  
pp. 2447-2472 ◽  
Author(s):  
Petr Maloň ◽  
C. L. Barness ◽  
Miloš Buděšínský ◽  
Rina K. Dukor ◽  
Dick Van der Helm ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optically Active ◽  
Vibrational Circular Dichroism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Circular Dichroïsm ◽  
C Nmr ◽  
Active Precursor

The title spirocyclic dilactam (1S,7S)-7-methyl-6,9-diazatricyclo[6,3,0,01,6]tridecan-5,10-dione (I), a molecule designed to contain non-planar amide groups, has been synthesized from an optically active precursor of known absolute configuration. The relative and absolute configuration have been determined by X-ray diffraction. The conformation of the compound has been investigated by X-ray, 1H and 13C NMR, electronic and vibrational circular dichroism. The compound possesses moderately non-planar amide groups in the two rings of nonequal geometry. The electronic CD is dominated by inherent chirality of the amide chromophores. The dilactams I and II ((1S,6S)-6-methyl-5,8-diazatricyclo[6,3,0,01,5]undecan-4,9-dione – having five-membered rings) exhibit monosignate amide I VCD and strong VCD bands in the mid-ir region.

Transition Metal Allyls, V. The Preparation and Structure of [NiX(PmenthylR1R2)(η3-allyl)] Complexes

1984 ◽  
Vol 39 (8) ◽  
pp. 1139-1150 ◽  
Author(s):  
H. Brandes ◽  
R. Goddard ◽  
P. W. Jolly ◽  
C. Krüger ◽  
R. Mynott ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Absolute Configuration ◽  
Phosphorus Atom ◽  
Optically Active ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute ◽  
Active Centres

A number of adducts formed by reacting [NiX(η3-allyl)]2 complexes with optically active tert.- phosphines, in which optically active centres are found both at the phosphorus atom and in a substituent, have been isolated and their structures investigated in solution by NMR spectroscopy. The absolute configuration of the phosphine in [NiCl{Pm enthyl(Me)But}(η3-C3H5)] has been determ ined by X-ray crystallography. The relevance of the results to the nickel-catalyzed asymmetric codimerisation of alkenes is discussed.

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