Chiral Induction in the Methylation of N-Ethoxycarbonylmethyl Sulfoximines

1986 ◽  
Vol 39 (11) ◽  
pp. 1833 ◽  
Author(s):  
TW Hambley ◽  
TW Hambley ◽  
B Raguse ◽  
B Raguse ◽  
DD Ridley ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Absolute Configuration ◽  
Sulfur Atom ◽  
Optically Active ◽  
Complex Mixtures ◽  
Lithium Diisopropylamide ◽  
Aryl Group ◽  
Methyl Group ◽  
X Ray ◽  
Chiral Induction

Chiral inductions in the C- methylations of four optically active N-ethoxycarbonylmethyl-S-p-tolylsulfoximines were explored by using the reagents lithium diisopropylamide (in tetrahydrofuran at -78°) then methyl iodide. When the fourth substituent at sulfur was a methyl group, complex mixtures of products were formed. However, when the fourth substituent was an aryl group, moderate yields of methylated compounds were formed and the ratio of diastereomers produced were 50 : 50 ( Ar = phenyl), 76 : 24 ( Ar = o- methoxyphenyl ) and 100 : 0 [ Ar = o-(2-methoxyethoxy)phenyl]. The diastereoselectivities are accounted for by intramolecular chelation of the aryl-oxygen substituents with the intermediate lithiated carbanion. The structure and absolute configuration where Ar = o-(2-methoxyethoxy )phenyl were confirmed by X-ray crystallographic methods. Space group P 212121, orthorhombic, a 10.2500(7), b 13.281(2), c 16.526(2) Ǻ; final R 0.064 (on 924F). The configuration at the sulfur atom is (S) and that induced at the carbon atom is (R).

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.

Crystal structure and absolute configuration of (+)-scandine hydrobromide

1982 ◽  
Vol 35 (8) ◽  
pp. 1655 ◽  
Author(s):  
JR Cannon ◽  
KD Croft ◽  
Y Matsuki ◽  
VA Patrick ◽  
RF Toia ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Absolute Configuration ◽  
Steric Effect ◽  
X Ray Diffraction ◽  
Methyl Group ◽  
X Ray ◽  
Block Diagonal

The major alkaloid of a Fijian Melodinus sp. (family Apocynaceae) has been identified as (+)-scandine (1). The crystal structure and absolute configuration of the acetone solvate of (+)-scandine hydrobromide have been determined by X-ray diffraction; diffractometer data at 295 K were refined by block diagonal least squares to a residual of 0.037 (2657 'observed' reflections). Crystals of the hydrobromide are monoclinic, P21, a 9.496(3), b 14.561(5), c 9.339(3) �, β 115.39(2)�, Z 2. Although the cations of (+)-scandine hydrobromide and (+)-N-methylmeloscine bromide have the same skeleton and the same absolute configuration, they have different conformations; this appears to be due to the steric effect of the N-methyl group in the latter cation.

On the Synthesis and Addition Reactions of Chiral N-Heterocyclic Diphosphines

2012 ◽  
Vol 67 (8) ◽  
pp. 765-773 ◽  
Author(s):  
Daniela Förstera ◽  
Ingo Hartenbach ◽  
Martin Nieger ◽  
Dietrich Gudat
Keyword(s):  
Single Crystal ◽  
Optically Active ◽  
Molecular Structures ◽  
Addition Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chiral Induction

Reaction of chiral N-heterocyclic chlorophosphines with lithium diphenylphosphide or of achiral N-heterocyclic chlorophosphines with optically active lithium menthyl phosphide produces chiral N-heterocyclic diphosphines which can be utilized in subsequent diphosphination reactions with activated alkenes or alkynes. The reaction with alkynes proceeds stereospecifically to produce Zethylene- 1,2-bisphosphines which are readily converted to nickel(II) or palladium(II) complexes. Reactions with alkenes are synthetically less useful as the addition proceeds without any chiral induction at the newly formed stereocenters to yield inseparable mixtures of diastereomeric products. The molecular structures of chiral Z-ethylene-1,2-bisphosphine complexes and of a chiral N-heterocyclic chlorophosphine have been determined by single-crystal X-ray diffraction

Preparation of New Optically Active Furanoids Containing Various Aza-Heterocyclic Moieties

1997 ◽  
Vol 62 (6) ◽  
pp. 894-912 ◽  
Author(s):  
Ali Werfeli ◽  
Jan Čejka ◽  
Ondřej Klecán ◽  
Bohumil Kratochvíl ◽  
Josef Kuthan
Keyword(s):  
Schiff Base ◽  
Acrylic Acid ◽  
Primary Alcohol ◽  
Optically Active ◽  
Complex Mixtures ◽  
Knoevenagel Reaction ◽  
Pyridinium Chloride ◽  
X Ray ◽  
Dihydropyridine Derivative ◽  
Pyridinium Perchlorate

The aldehyde 2 prepared from [5-(2,3-O-isopropylidene-β-D-erythrofuranosyl)-2-methylfuran-3-yl]methanol (1) was converted to E,Z-oximes 3, 4 and imine derivative 5 by the reaction with hydroxylamine and pyridin-2-yl amine, respectively. The Knoevenagel reaction with malonic acid afforded exclusively the 3-substituted acrylic acid 6 while corresponding Hantzsch 1,4-dihydropyridines 7 and 8 were obtained by the reaction of aldehyde 2 with ethyl acetoacetate or acetylacetone and ammonia. 3,5-Dicyano-1,4-dihydropyridine derivative 9 was isolated only in forms of hydrates after the reaction of aldehyde 2 with 3-aminocrotonitrile. 1,4-Dihydropyridines 7 and 9 were aromatized to corresponding pyridines 10 and 11. Isoxazoles 12, 13 and isoxazolines 14, 15 were prepared by 1,3-cycloaddition of appropriate dienophiles to a nitrile oxide generated from aldoximes 3, 4. Ferricyanide oxidation of 1-{[5-(2,3-O-isopropylidene-β-D-erythrofuranosyl)-2-methylfuran-3-yl]methyl}pyridinium chloride (17a), -3-methylpyridinium chloride (19a) and the corresponding isoquinolinium chloride 21a gave optically active pyridin-2(1H)-ones 22, 23 and 2H-isoquinolone derivative 24 while the procedure with 2-methylpyridinium salt 18a and 4-methylpyridinium salt 20a led to complex mixtures of products. Reaction of 2,4,6-triphenylpyrylium perchlorate with furanoid amine 26 afforded a mixture of major 2,4,6-triphenylpyridine, minor pyridinium perchlorate 25 and primary alcohol 1. The absolute configuration of the studied compounds has been confirmed by X-ray analysis of the Schiff base 5.

scholarly journals Diastereoisomerically Pure, (S)-O-1,2-O-isopropyli dene-(5-O-α-d-glucofuranosyl) t-butanesulfinate: Synthesis, Crystal Structure, Absolute Configuration and Reactivity

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3392
Author(s):  
Bogdan Bujnicki ◽  
Jarosław Błaszczyk ◽  
Marek Chmielewski ◽  
Józef Drabowicz
Keyword(s):  
Crystal Structure ◽  
Absolute Configuration ◽  
Sulfur Atom ◽  
Asymmetric Unit ◽  
Orthorhombic System ◽  
X Ray ◽  
X Ray Crystallography ◽  
Trigonal Bipyramidal ◽  
Single Compound ◽  
Leaving Groups

The reaction of t-butylmagnesium chlorides with diastereomerically pure (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-α-d-glucofuranose (R)-4 was found to be stopped at the stage of the corresponding, diastereoisomerically pure 1,2-O-isopropylidene-(5-O-α-d-glucofuranosyl) t-butanesulfinate (S)-10 for which the crystal structure and the (S)-absolute configuration was determined by X-ray crystallography. Comparison of the absolute configurations of the starting sulfite (R)-4, and t-butanesulfinate (S)-10 (which crystallizes in the orthorhombic system, space group P212121, with the single compound molecule present in the asymmetric unit), clearly indicates that the reaction of nucleophilic substitution at the stereogenic sulfur atom in the sulfite (R)-4 occurs with the full inversion of configuration via the trigonal bipyramidal sulfurane intermediate 4c in which both the entering and leaving groups are located in apical positions.

Reaktioneil mit N,N-Bis(trimethylstannyl)trifluormethansulfonamid und die Röntgenstrukturanalyse eines zwölfgliedrigen Schwefel-Stickstoff-Ringes / Reactions with N,N-Bis(trimethylstannyl)trifluoromethanesulfonamide and the X-ray Structure of a Twelve-Membered Sulfur-Nitrogen-Ring

1979 ◽  
Vol 34 (6) ◽  
pp. 814-821 ◽  
Author(s):  
Herbert W. Roesky ◽  
Manfred Diehl ◽  
Bernt Krebs ◽  
Michael Hein
Keyword(s):  
Sulfur Atom ◽  
Title Compound ◽  
Chair Conformation ◽  
Membered Ring ◽  
Molar Ratio ◽  
Monoclinic Space Group ◽  
Methyl Group ◽  
X Ray ◽  
Germanium Compound ◽  
Nitrogen Ring

The title compound N,N-bis(trimethylstannyl)trifluoromethanesulfonamide (1) reacts with S2Cl2, SOCl2 and SO2Cl2 in a molar ratio 2:1 to yield the compounds S2Cl2 a twelve-membered ring 6. These are the largest neutral sulfur-nitrogen rings of coordination number two at the sulfur atoms known to date. 3 reacts with SOCI2 under migration of a methyl group from the tin to a sulfur atom to yield CF3SO2(R3Sn)NS(CH3)NSO2CF3 (7). 2,2,4,4-Tetramethyl-1,3-bis(trifluormethylsulfonyl)cyclodisilazan and 7 are formed by the reaction of 3 with R2SiCl2- The analogous four-membered germanium compound 8 is obtained from 1 and R2GeCl2. While the pyrolysis of 1 yields only the six-membered cyclotristannazan 9, the six-membered germanium analog is only formed in minor amounts. By treating 9 with R3SiCl the ring is decomposed to give 10. A six-membered ring is formed from the reaction of 1 with ClR2SiOSiR2Cl 11. The structure of 6 is discussed in detail. 6 crystallizes in the monoclinic space group C2/c with a = 24.408(5), b = 7.377(2), c = 16.715(3) Å, β = 117.16(3)° and Z = 4. It has a chair conformation which is different from the isoelectronic S12-structure.

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