Enolic Ortho Esters. VII Involvement of Magnesium Halides as Lewis Acids in the Reaction of Grignard Reagents with 1,6-Dideoxy- 1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5- enopyranose and its 6-Phenyl Derivative: a Correction

1998 ◽  
Vol 51 (8) ◽  
pp. 681 ◽  
Author(s):  
David J. Collins ◽  
Angus I. Hibberd ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Single Crystal ◽  
Lewis Acids ◽  
Titanium Tetrachloride ◽  
Grignard Reagents ◽  
Ortho Ester ◽  
X Ray ◽  
Phenyl Derivative ◽  
Methylmagnesium Iodide ◽  
Ortho Esters ◽  
Phenylmagnesium Bromide

The known aldehyde methyl 2,3,4-tri-O-methyl-α-D-gluco-hexodialdo-1,5-pyranoside (9) was converted in eight steps into the 6-phenyl glucose-derived enolic ortho ester (Z)-1,6-dideoxy-1,1-ethylenedioxy- 2,3,4-tri-O-methyl-6-phenyl-D-xylo-hex-5-enopyranose (22), the geometry of which was established by a single-crystal X-ray study. Treatment of the 6-phenyl enolic ortho ester (22) with titanium tetrachloride at –78° effected clean rearrangement into (2R/S,4R,5R,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-2-phenylcyclohexanone (26). Reaction of (22) with methylmagnesium iodide gave (1R,2S,4R,5S,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-1-methyl-2-phenylcyclohexanol (24), the structure and stereochemistry of which were established by an X-ray study. Reaction of (22) with phenylmagnesium bromide gave (25), the 1-phenyl analogue of (24). The firmly established structure of (24) led to proof both chemically and by X-ray means that the product from reaction of 1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose (5) with methylmagnesium iodide has the hydroxy acetal structure (7) rather than the originally assigned hemiacetal structure (3).

Enolic Ortho Esters. VI. A New 'Pyranose→Cyclohexane' Transformation via 1,6-Dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose

1996 ◽  
Vol 49 (3) ◽  
pp. 425 ◽  
Author(s):  
DG Bourke ◽  
DJ Collins ◽  
AI Hibberd ◽  
MD Mcleod
Keyword(s):  
Titanium Tetrachloride ◽  
Ortho Ester ◽  
Methylmagnesium Iodide ◽  
Swern Oxidation ◽  
Ortho Esters ◽  
Trimethylsilyl Trifluoromethanesulfonate ◽  
Hydrolysis Of

Hydrolysis of methyl 6-chloro-6-deoxy-2,3,4-tri-O-methyl-α-D-glucopyranoside (19b) and Swern oxidation of the resulting anomeric hemiacetals (20) gave 6-chloro-6-deoxy-2,3,4-tri-O-methyl-D-glucono-1,5-lactone (21), treatment of which with 1,2-bis( trimethylsilyloxy )ethane in the presence of trimethylsilyl trifluoromethanesulfonate gave 6-chloro-1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-glucopyranose (23a). Conversion of (23a) into the corresponding 6-iodo compound (23b) and treatment of this with 1,8-diazabicyclo[5.4.0]undec-7-ene afforded the enolic ortho ester 1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose (26). Reaction of (26) with methylmagnesium iodide, or with titanium tetrachloride, gave (1R,6S,7R,8R,9S)-7,8,9-trimethoxy-6-methyl-2,5-dioxabicyclo[4.3.1]decan-1-ol (34), or (2S,3R,4R)-5,5-ethylenedioxy-2,3,4-trimethoxycyclohexanone (28), respectively.

scholarly journals Crystal structures of titanium–aluminium and –gallium complexes bearing twoμ2-CH3units

2017 ◽  
Vol 73 (5) ◽  
pp. 691-693 ◽  
Author(s):  
Tim Oswald ◽  
Mira Diekmann ◽  
Annika Frey ◽  
Marc Schmidtmann ◽  
Rüdiger Beckhaus
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Lewis Acids ◽  
Methyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Methyl Methyl ◽  
Low Valent ◽  
Titanium Aluminium ◽  
Gallium Complexes

The isotypic crystal structures of two titanocene complexes containing anEMe3unit (E =Al, Ga; Me = methyl) with twoμ2-coordinating methyl groups, namely [μ-1(η5)-(adamantan-1-yl-2κC1)cycylopentadienyl]di-μ2-methyl-methyl-2κC-[1(η5)-pentamethylcyclopentadienyl]aluminiumtitanium(III), [AlTi(CH3)3(C10H15)(C15H18)], and [μ-1(η5)-(adamantan-1-yl-2κC1)cycylopentadienyl]di-μ2-methyl-methyl-2κC-[1(η5)-pentamethylcyclopentadienyl]galliumtitanium(III), [GaTi(CH3)3(C10H15)(C15H18)], are reported. Reacting a dinuclear nitrogen-bridged low-valent titanium(III) complex with the Lewis acids AlMe3or GaMe3results in the loss of molecular dinitrogen and the formation of two monomeric titanocene(III) fragments bearing twoμ2-bridging methyl groups. Single crystal X-ray diffraction reveals the formation of a newE—C bond involving the pentafulvene ligand while the bridging and terminal methyl groups remain intact.

Synthesis of heteronuclear bifunctional Lewis acids by transmetalation of 1,8-bis(trimethylstannyl)naphthalene with BCl3

2002 ◽  
Vol 80 (10) ◽  
pp. 1308-1312 ◽  
Author(s):  
Marcus Schulte ◽  
François P Gabbaï
Keyword(s):  
Elevated Temperature ◽  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Acid Derivative ◽  
Lewis Acid ◽  
Lewis Acids ◽  
The Novel ◽  
X Ray ◽  
Boron Center ◽  
Chloride Methyl

Reaction of 1,8-bis(trimethylstannyl)naphthalene (1) with an excess of BCl3 at –78°, followed by warming to 0°C, results in the exclusive formation of the novel bifunctional Lewis acid 1-(chlorodimethylstannyl)-8-(dichloroboryl)naphthalene (2), a compound in which a boryl and a stannyl moiety coexist at the peri-positions of a naphthalene core. At elevated temperature compound 2 undergoes a chloride–methyl exchange, which affords 1-(dichloromethylstannyl)-8-(chloromethylboryl)naphthalene (3). Compounds 2 and 3 have been characterized by multi-nuclear NMR spectroscopy. The single crystal X-ray analysis for compound 3 reveals a sterically crowded structure with an essentially trigonal planar boron center, and a tin center pentacoordinated in a [4+1]-fashion. Upon exposure to traces of water, compound 3 is converted into the borinic acid derivative 1-(dichloromethylstannyl)-8-(hydroxymethylboryl)naphthalene (4), which has been characterized by multi-nuclear NMR spectroscopy and single crystal X-ray analysis.Key words: multidentate Lewis acids, organoboranes, organostannanes.

scholarly journals Carbamoyl Derivatives of a Pyridine-Based Tetraamine

2007 ◽  
Vol 62 (4) ◽  
pp. 519-522 ◽  
Author(s):  
Anvarhusen K. Bilakhiya ◽  
Frank W. Heinemann ◽  
Andreas Grohmann
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Structure Determination ◽  
Spectroscopic Data ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Phenyl Derivative ◽  
High Yields ◽  
Derivatives Of

The reaction of four equivalents of phenyl or tert-butyl isocyanate with the pyridine-derived tetraamine 2,6-C3H3N[CMe(CH2NH2)2]2 in toluene gives high yields of the quadruply ureido substituted products 2,6-C5H3N[CMe(CH2R)2]2 [R = -NH(CO)NHPh and -NH(CO)NHtBu]. Full spectroscopic data for both compounds are given. A single crystal X-ray structure determination of the phenyl derivative reveals an intricate network of both intra- and intermolecular hydrogen bonds involving the C=O and both NH functionalities in all ureido groups.

Partial Reduction of the N–O Functions of Partially Deprotonated Bis(hydroxylamine) Complexes

2009 ◽  
Vol 64 (10) ◽  
pp. 1208-1212
Author(s):  
Patrick Bösing ◽  
Hans-Georg Stammler ◽  
Norbert W. Mitzel
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Titanium Tetrachloride ◽  
Partial Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amine Function ◽  
C Nmr

The reduction of a partially deprotonated bishydroxylamine complex {(tBu2Ga)2[cyclo-ON(Me)(CH2)2- (Me)NO][HON(Me)(CH2)2(Me)(H)NO]} with a reagent composed of titanium tetrachloride and methyllithium leads to the reduction of one of the N-O groups to an amine function affording the salt {(tBu2Ga)[cyclo- ON(H)(Me)(CH2)2NHMe]}+ {tBu2GaCl2}−. This has been characterised by 1H and 13C NMR spectroscopy, by elemental analysis and by single crystal X-ray diffraction, showing the neutral amine/hydroxylamine ligand to be present in its tautomeric aminoxide form. The molecules form hexameric cyclic aggregates by N-H···Cl hydrogen bonds.

Reassignment of the Compounds Reported to be 4,5-Dihydro-3H-1-benzazepin-5-ols as 2,3,4,5-Tetrahydro-2,5-epoxy-1H-1-benzazepines and 3,4,5,6-Tetrahydro-1,6-benzodiazocines as 2,3,3a,4-Tetrahydro-1H-pyrrolo[1,2-a]benzimidazoles

1993 ◽  
Vol 46 (10) ◽  
pp. 1623 ◽  
Author(s):  
D Anastasiou ◽  
EM Campi ◽  
GD Fallon ◽  
WR Jackson
Keyword(s):  
Single Crystal ◽  
Structure Determination ◽  
X Ray ◽  
Phenyl Derivative

Reexamination of the 1H and 13C n.m.r. spectra of the supposed 4,5-dihydro-3H-1-benzazepin-5-ols (1) has led to a reassignment of their structure as 2,3,4,5-tetrahydro-2,5-epoxy-1H-1-benzazepines (3) and the new structure has been confirmed by a single-crystal X-ray structure determination of the 5-phenyl derivative (3; R1 = H, R2 = Ph). Similar examination of the n.m.r. spectra of the supposed 3,4,5,6-tetrahydro-1,6-benzodiazocines (2) has led to their reassignment as the pyrrolo [1,2-a] benzimidazoles (4).

Formal Synthesis of Both Atropomers of Desertorin C and an Example of Chirality Transfer from a Biphenyl Axis to a Spiro Centre and its Reverse

2000 ◽  
Vol 53 (6) ◽  
pp. 487 ◽  
Author(s):  
Robert W. Baker ◽  
Rekha V. Kyasnoor ◽  
Melvyn V. Sargent ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Single Crystal ◽  
Major Product ◽  
Structural Determination ◽  
Chirality Transfer ◽  
Formal Synthesis ◽  
X Ray ◽  
Similar Product ◽  
Phenylmagnesium Bromide

In connection with the synthesis of 4,4′,7,7′-tetramethoxy-5,5′-dimethyl-6,8′-bicoumarin (desertorin C) (11) in enantiopure form, the diastereomeric ratios of the products of the reactions between 2-isopropyloxy-6-methoxy-4- methylphenylmagnesium bromide (24) and (4S)-4-isopropyl-2-(2,3,5-trimethoxyphenyl)-4,5-dihydrooxazole (23), between 2,4-dimethoxy-6-methylphenylmagnesium bromide (37) and (4S)-4-isopropyl-2-(2,3-dimethoxy-5-methylphenyl)-4,5-dihydrooxazole (36), and between 2,4-dimethoxy-6-(t-butyldimethylsilyloxy)methyl-phenylmagnesium bromide (46) and the oxazole (36) were explored. The major product of the last mentioned reaction was converted into (S,4S)-4-isopropyl-2-(2′-hydroxymethyl-4′,6,6′-trimethoxy-4-methyl-1,1′-biphenyl-6-yl)-4,5-dihydroxazole (49), the axial configuration of which was confirmed by single crystal X-ray structural determination. The similar product (S,4S)-2-(2′,4′,6-trimethoxy-4,6′-dimethyl-1,1′-biphenyl-6-yl)-4,5-dihydrooxazole (43) was converted into (S)-1-(2,4′,6′-trimethoxy-4,6′-biphenyl-2-yl)ethanone (57) which furnished (S)-1-(2′,4′,6-trimethoxy-4,6′-dimethyl-1,1′-biphenyl-2-yl)acetamide (58) (43%) and (S)-2,7′-dimethoxy-3′,5′,6-trimethylspiro[cyclohexa-2,5-diene-1,1′-(1H)isoindole]-4-one (61) (30%) on Schmidt rearrangement. The dienone (61) on reduction and methylation regenerated the ketone (57). The methodology of Lipschutz was adapted for the synthesis of both enantiomers of 1,1′-(2′,4-dihydroxy-6,6′-dimethoxy-2,4′-dimethylbiphenyl-3,3′-diyl)bisethanone (32) and (83) which constitutes a formal synthesis of both enantiomers of desertorin C.

Synthesen und Kristallstrukturen von Bis(N-lithiumtrimethylsilylamino)- bis(dimethylamino)silan und 1,1-Dichloro-2,4-bis(trimethylsilylamino)- 3,3-bis(dimethylamino)siladiazatitanacyclobutan / Syntheses and Crystal Structures of Bis(N-lithio-trimethylsilylamino)bis(dimethylamino)- silane and 1,1-Dichloro-2,4-bis(trimethylsilylamino)-3,3-bis(dimethylamino)siladiazatitanacyclobutane

2002 ◽  
Vol 57 (9) ◽  
pp. 976-982
Author(s):  
Josef Engering ◽  
Eva-Maria Peters ◽  
Martin Jansen
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Titanium Tetrachloride ◽  
Solution Nmr ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solution Nmr Spectroscopy

Bis(N-lithio-trimethylsilylamino)bis(dimethylamino)silane (1) is formed in the reaction of silicon tetrachloride with excess hexamethyldisilazane, followed by halogen substitution using two equivalents of LiN(CH3)2, and treatment with two equivalents of n-butyllithium in hexane. 1, found to be dimeric in the solid state, was characterised by single crystal X-ray diffraction (monoclinic, C2/c, a = 1925.2(4), b = 1501.7(2), c = 1389.7(3) pm, β= 101.98(2), Z = 4, C20H60Li4N8Si6), and by solid state and solution NMR spectroscopy and mass spectrometry. Further reaction with titanium tetrachloride (molar ratio 1:1) yields orange crystals of the dimer [TiClf(μ2-NSi(CH3)3)2Si(N(CH3)2)μ2-Cl]2 (2) characterised by single crystal X-ray diffraction (triclinic, P1, a = 942.1(4), b = 991.7(4), c = 1222.6(5) pm, α= 90.12(1), β= 94.42(2), γ= 107.64(1)°, Z = 1, C20H60Cl4N8Si6Ti2)

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