scholarly journals Synthesis of Some Biologically Important 3-Oxacepham Derivatives

1970 ◽  
Vol 5 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Mohammad Rafiqul Islam ◽  
Mohammad Nurnabi ◽  
AM Sarwaruddin Chowdhury ◽  
Mohammad Mehdi Masud
Keyword(s):  
Key Words ◽  
Full Text ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
Tert Butyl ◽  
Relative Stereochemistry

The 6H-oxathiazines 1a-e having imine moiety underwent [2+2] cycloaddition with phenoxyacetylchloride in the presence of Et3N to give β-lactam derivatives 2a-e in high yield. The X-ray crystallographic analysis revealed the relative stereochemistry that the substituents at C-2 and C-4 were cis configurated. The subtituents at C-6 and C-7 were also cis to each other. However, the 6H-oxathiazines 1f-i containing tert-butyl or methyl group at C-4 did not undergo the cycloaddition. Key words: Azetedinone, β-lactam, oxacepham, cycloaddition, imine, ketene, oxathiazine. Dhaka Univ. J. Pharm. Sci. Vol.5(1-2) 2006 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

The Pyrolytic Rearrangement of 1-Alkynoyl-3-methylpyrazoles: Synthesis of Pyrazolo[1,5-a]pyridin-5-ols and Related Compounds

1994 ◽  
Vol 47 (6) ◽  
pp. 991 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon ◽  
SC Lee ◽  
RP Mcgeary
Keyword(s):  
Carbon Chain ◽  
Ring Structure ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Fused Ring ◽  
Related Compounds

Flash vacuum pyrolysis of 1-(alkyn-2′-oyl)-3-methylpyrazoles at 650°/0.03 mm forms pyrazolo[1,5-a]pyridin-5-ols, often in high yield, which may bear substituents at C2, C3 or C7. In the absence of a 3-methyl group in the precursor, N-ethynylpyrazoles are formed in low yield. The formation of both types of product is interpreted as involving 3-(N-pyrazolyl)propadienones formed by N1 → N2 migration of the N-alkynoyl group with inversion of the three-carbon chain. The fused-ring structure of 2-methylpyrazolo[1,5-a]pyridin-5-ol (25) was established by X-ray crystallography of the O-benzoyl derivative (27).

The Crystal Structure of Dimethyl (1aα,2aα,5β,6aβ-Hexahydroazirino[2,1-b]benzoxazole-1a, 5(1H)-dicarboxylate

1991 ◽  
Vol 44 (8) ◽  
pp. 1145 ◽  
Author(s):  
MF Mackay ◽  
M Campbell ◽  
MJ Mcleish
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Crystallographic Analysis ◽  
Aminobenzoic Acid ◽  
X Ray ◽  
Relative Stereochemistry

The title compound formed the major component in a rearrangement of an analogue of 4-amino-4-deoxychorismic acid (1), an intermediate in the chorismate-p-aminobenzoic acid biotransformation. X-Ray crystallographic analysis has defined the relative stereochemistry at the four chiral centres in the tricyclic molecule.

scholarly journals Attempted Synthesis and Unexpected β-Fragmentation of a Hindered β-Keto Nitroxide

2017 ◽  
Vol 70 (10) ◽  
pp. 1106 ◽  
Author(s):  
Chris Edwards ◽  
Peter C. Healy ◽  
W. Ken Busfield ◽  
Ezio Rizzardo ◽  
San H. Thang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Ring Opening ◽  
Sodium Tungstate ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Fragmentation Mechanism ◽  
Pentanoic Acid ◽  
X Ray ◽  
Ring Opening Reaction

The attempted synthesis of a β-keto imidazolidinone nitroxide by oxidation of the β-hydroxy imidazolidinone precursor with hydrogen peroxide and sodium tungstate led to an unexpected ring-opening reaction to produce 1,4-diazaspiro[4.5]dec-1-en-3-oxo-2-pentanoic acid 1-oxide (13) in high yield. The structure of 13 was confirmed by X-ray crystallographic analysis. A β-fragmentation mechanism is suggested for the oxidative ring-opening reaction.

The direct electrochemical synthesis of thiolato complexes of cobalt and nickel, and the crystal structure of bis(phenylthiolato)bis(1,10-phenanthroline)cobalt(III) perchlorate

1988 ◽  
Vol 66 (9) ◽  
pp. 2151-2156 ◽  
Author(s):  
Raj K. Chadha ◽  
Rajesh Kumar ◽  
Jaime Romero Lopez-Grado ◽  
Dennis G. Tuck
Keyword(s):  
Crystal Structure ◽  
Electrochemical Oxidation ◽  
Electrochemical Synthesis ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Metal Anode ◽  
Aerial Oxidation ◽  
Perchlorate Salt ◽  
Cobalt And Nickel

Cobalt(II) and nickel(II) thiolates, M(SR)2, can be prepared in high yield by the electrochemical oxidation of a metal anode in an acetonitrile or acetone solution of RSH (R = C6H5, o-CH3C6H4, 2-C10H7, 2,3,4,5-C6F4H; not all combinations). When 2,2-bipyridine or 1,10-phenanthroline (=L) is added to the electrolyte phase, the products are the adducts M(SR)2L2. In the case of Co(SC6H5)2(phen)2, aerial oxidation leads to the formation of the cobalt(III) cation [Co(SC6H5)2(phen)2]+, isolated as the perchlorate salt. X-ray crystallographic analysis showed that this cation has a cis-CoS2(N2)2 kernel.

scholarly journals 2-Deoxy-2-fluoro-2-C-methyl-D-ribono-1,4-lactone (fluoromethylrib)

2006 ◽  
Vol 62 (4) ◽  
pp. o1208-o1210
Author(s):  
Samuel Parker ◽  
David Watkin ◽  
Benjamin Mayes ◽  
Richard Storer ◽  
Sarah Jenkinson ◽  
...  
Keyword(s):  
Title Compound ◽  
Crystallographic Analysis ◽  
Ring Size ◽  
X Ray ◽  
Compound C ◽  
Relative Stereochemistry

The relative stereochemistry of the fluoro substituent (as ribo) and the ring size of the lactone (as five) in the title compound, C6H9FO4, have been established by X-ray crystallographic analysis.

Sense of sequential 1,5-sigmatropic rearrangements of dimethyl-3,3-dialkyl-3H-pyrazole-4,5-dicarboxylates. Crystal and molecular structures of two dimethyl-4,5-dialkyl-1H-pyrazole-1,3-dicarboxylates

1991 ◽  
Vol 69 (3) ◽  
pp. 373-378 ◽  
Author(s):  
Christopher S. Frampton ◽  
Michael W. Majchrzak ◽  
John Warkentin
Keyword(s):  
Dicarboxylic Acid ◽  
Key Words ◽  
Dimethyl Ester ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Methyl Group ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Sigmatropic Rearrangements ◽  
Methoxycarbonyl Group

3,3-Dialkyl-3H-pyrazole-4,5-dicarboxylic acid dimethyl esters (4), obtained by cycloaddition of R1R2C=N+=N− (R1 = R2 = CH3; R1 = CH3, R2 = CH2CH3) to CH3O2CC≡CCO2CH3, rearrange thermally by 1,5-sigmatropic alkyl shifts to both N and C. The latter rearrangement is followed by two successive 1,5-sigmatropic shifts of a methoxycarbonyl group. Final products of the threefold rearrangement were shown to be 4,5-dialkyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl esters (6), rather than the isomeric 3,4-dialkyl-1H-pyrazole-1,5-dicarboxylic acid dimethyl esters (7), by means of single crystal X-ray diffraction. Those products therefore result from alkyl migration to C-4 of 4, followed by sequential migration of the methoxycarbonyl group, initially at C-4, to C-3 and then to N-2 of 4. In the initial alkyl migration step, ethyl migrates in preference to methyl, and in subsequent migration steps the methoxycarbonyl group migrates faster than the ethyl or methyl group. Crystals of 4-ethyl-5-methyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl ester (6b) are monoclinic, of space group P21/n, with a = 7.907(1) Å, b = 11.087(2) Å, c = 13.199(3) Å, V = 1124.9(4) Å 3, Dc = 1.34 g cm−3, Dm = 1.33 g cm−3 for Z = 4, and R1 = 0.0772 (R2 = 0.0626) for 1474 reflections (R1 = 0.0428, R2 = 0.0422 for 903 reflections with I > 3σ(I)). The structure of 6a is similar. Key words: 3,3-dialkyl-3H-pyrazoles, 1,5-sigmatropic rearrangements of; 4,5-dialkyl-1H-pyrazoles, crystal and molecular structures; 1,5-sigmatropic rearrangements of pyrazoles, sense of.

An Approach to the Total Synthesis of Diterpenoid Plant Growth Substances Isolated From Gametophytes of the Fern Genus Anemia

1992 ◽  
Vol 45 (1) ◽  
pp. 227 ◽  
Author(s):  
CKF Chiu ◽  
LN Mander ◽  
AD Stuart ◽  
AC Willis
Keyword(s):  
Total Synthesis ◽  
Liquid Ammonia ◽  
Crystallographic Analysis ◽  
Aldol Reactions ◽  
Growth Substances ◽  
Enol Ether ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Plant Growth Substances

Reduction of the oxoindan acid (9) by potassium in liquid ammonia followed by in situ alkylation with 3-methylbut-2-enyl bromide furnished enol ether (14) which was transformed into the acetal (17) and thence aldehydes (18; R = COCH3 and COCHCl2). Acid- catalysed aldol reactions then afforded the ethanoindene derivatives (19; R=COCH3 and COCHCl2). Further elaboration gave carbinol (28) which is envisaged as an intermediate for the total synthesis of the diterpenoid antheridiogens obtained from gametophytes of the fern genus Anemia, including acid (2). The relative stereochemistry of acetal (17) was established by X-ray crystallographic analysis.

Dihydropyridines in synthesis and biosynthesis. III. Coupling of dihydropyridinetricarbonylchromium(0) complexes: bipyridyls

1982 ◽  
Vol 60 (3) ◽  
pp. 323-326 ◽  
Author(s):  
James P. Kutney ◽  
Lucas Kaczmarek ◽  
Danuta Mostowicz ◽  
Brian R. Worth
Keyword(s):  
Low Temperature ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Methyl Pyridine

Reaction of 1,2- and 1,6-dihydro-3-ethyl-N-methyl pyridine tricarbonylchromium(0) complexes with methyllithium at low temperature afforded a high yield of dimeric tricarbonylchromium(0) complexes. Structures of the latter products were established by X-ray crystallographic analysis. Some chemistry of these novel compounds is described.

scholarly journals (5R,6R)-rel-9-tert-Butyl-trans-5,6-dimethoxy-6,7-dihydro-5H-benzocycloheptene

IUCrData ◽  
2017 ◽  
Vol 2 (10) ◽  
Author(s):  
Alan J. Lough ◽  
Emily Carlson ◽  
William Tam
Keyword(s):  
Title Compound ◽  
Membered Ring ◽  
Boat Conformation ◽  
X Ray ◽  
Tert Butyl ◽  
Compound C ◽  
Relative Stereochemistry

The relative stereochemistry of the title compound, C17H24O2, has been confirmed by the X-ray analysis. The seven-membered ring is in a pseudo-boat conformation with both methoxy substituents in equatorial sites.

Synthesis and Structure of the Potassium Salt with Monodeprotonated 1,2,3-Tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene

2008 ◽  
Vol 61 (7) ◽  
pp. 537 ◽  
Author(s):  
Ze-Bao Zheng ◽  
Ren-Tao Wu ◽  
Ji-Kun Li ◽  
Yi-Feng Sun
Keyword(s):  
Potassium Salt ◽  
Crystallographic Analysis ◽  
Potassium Ion ◽  
High Yield ◽  
Cone Conformation ◽  
X Ray ◽  
Partial Cone ◽  
Phenyl Rings ◽  
Close Contacts

Alkylation of p-t-butylcalix[6]arene with ethyl 4-bromobutanoate in the presence of K2CO3 results in a potassium salt of the monodeprotonated 1,2,3-tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene in high yield. X-Ray crystallographic analysis shows that this compound exists as a double partial cone conformation. The potassium ion is positioned near the centre of the cavity of the macrocycle and binds to four phenolic oxygens. Close contacts between the potassium ion and phenyl rings observed in this compound are indicative of the presence of the cation–π interaction. The molecules are connected via intermolecular K+···O interactions into infinite chains.

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