Total synthesis of polyoximic acid

2001 ◽  
Vol 79 (11) ◽  
pp. 1812-1826 ◽  
Author(s):  
Stephen Hanessian ◽  
Jian-min Fu
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Total Synthesis ◽  
Wittig Reaction ◽  
2D Nmr ◽  
Amino Acid Derivative ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Correct Structure

The structure and stereochemistry of polyoximic acid, a degradation product of polyoxins, was originally designated as trans-3-ethylidene-L-azetidine-2-carboxylic acid. However, total synthesis revealed that the correct structure was in fact cis-3-ethylidene-L-azetidine-2-carboxylic acid, which was confirmed by X-ray crystallography. The synthesis of the trans-isomer was also done and its identity was confirmed by X-ray analysis as well. The key step for constructing the four-membered ring was a rhodium catalyzed carbenoid insertion into the N—H bond of a beta-amino acid derivative. The stereoselectivity of the exo-double bond was controlled by conducting a Horner-Emmons-Wadsworth or a Wittig reaction to generate the trans- and cis-isomers, respectively. Weinreb's amide was used as a latent methyl group for the separation of trans and cis mixtures. The double bond stereochemistry of polyoximic acid in the parent polyoxin was also confirmed to be cis by extensive 2D NMR studies.Key words: diazoinsertion, azetidine, olefination.

The Chemistry of Ethyl 2-Ethoxycarbonyl-5,5-Diphenylpenta-2,3,4-Trienoate, a Potential Precursor of Ph2c=C=C=C=C=O

1987 ◽  
Vol 40 (10) ◽  
pp. 1675 ◽  
Author(s):  
NR Browne ◽  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon
Keyword(s):  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Wittig Reaction ◽  
Cyclization Reactions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Concentrated Sulfuric Acid ◽  
Triphenylphosphonium Bromide ◽  
Hydrolysis Of ◽  
Potential Precursor

The title diester , Ph2C=C=C=C( COOEt )2 (2), has been prepared by a Wittig reaction between (2-bromo-3,3-diphenylprop-2-en-1-yl) triphenylphosphonium bromide and diethyl 2-oxopropane-1,3-dioate ( mesoxalic ester). The diester (2) undergoes cyclization reactions in concentrated sulfuric acid to give diethyl 2-(3'-phenyl-1H-inden-1'-y1idene)propane-l,3-dioate (4) and triethyl 3-oxo-3',9-diphenyl-2,3-dihydrospiro[lH-fluorene-1,l'-[1H]indene]-2,2,4-tricarboxylate (6), the structure of which was determined by X-ray crystallography. The title diester (2)adds cyclopentadiene across the 2,3-C=C bond to give diethyl 3-(2',2'-diphenylethenylidene)bicyclo[2.2.l]hept-5-ene-2,2-dicarboxylate (10). Alkaline hydrolysis of diester (10) gives an unstable colourless acid and a stable yellow crypto acid shown by X-ray crystallography to be 3-(2',2'-diphenylethenyl)bicyclo[2.2.l]hepta-2,5-diene-2-carboxylic acid (12). Attempts to convert diesters (2) and acid (12) into derivatives suitable for pyrolytic generation of Ph2C=C=C=C=C=O failed; The mono-acid chloride (14) yielded a small phenylazulene fraction on pyrolysis at 780-800°/0.02 mm.

scholarly journals Phenylhydrazone and Quinazoline Derivatives from the Cold-Seep-Derived Fungus Penicillium oxalicum

Marine Drugs ◽  
2020 ◽  
Vol 19 (1) ◽  
pp. 9
Author(s):  
Ya-Ping Liu ◽  
Sheng-Tao Fang ◽  
Zhen-Zhen Shi ◽  
Bin-Gui Wang ◽  
Xiao-Nian Li ◽  
...  
Keyword(s):  
Deep Sea ◽  
Spectroscopic Data ◽  
2D Nmr ◽  
Penicillium Oxalicum ◽  
Marine Phytoplankton ◽  
Cold Seep ◽  
Phytoplankton Species ◽  
X Ray ◽  
X Ray Crystallography ◽  
Quinazoline Derivatives

Three new phenylhydrazones, penoxahydrazones A–C (compounds 1–3), and two new quinazolines, penoxazolones A (compound 4) and B (compound 5), with unique linkages were isolated from the fungus Penicillium oxalicum obtained from the deep sea cold seep. Their structures and relative configurations were assigned by analysis of 1D/2D NMR and mass spectroscopic data, and the absolute configurations of 1, 4, and 5 were established on the basis of X-ray crystallography or ECD calculations. Compound 1 represents the first natural phenylhydrazone-bearing steroid, while compounds 2 and 3 are rarely occurring phenylhydrazone tautomers. Compounds 4 and 5 are enantiomers that feature quinazoline and cinnamic acid units. Some isolates exhibited inhibition of several marine phytoplankton species and marine-derived bacteria.

scholarly journals Fusarins G–L with Inhibition of NO in RAW264.7 from Marine-Derived Fungus Fusarium solani 7227

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 305
Author(s):  
Guangyuan Luo ◽  
Li Zheng ◽  
Qilin Wu ◽  
Senhua Chen ◽  
Jing Li ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
2D Nmr ◽  
Inflammatory Activity ◽  
Raw264.7 Cells ◽  
Spectroscopic Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structure Activity ◽  
Ic50 Values ◽  
New Compounds

Six new fusarin derivatives, fusarins G–L (1–6), together with five known compounds (5–11) were isolated from the marine-derived fungus Fusarium solani 7227. The structures of the new compounds were elucidated by means of comprehensive spectroscopic methods (1D and 2D NMR, HRESIMS, ECD, and ORC) and X-ray crystallography. Compounds 5–11 exhibited potent anti-inflammatory activity by inhibiting the production of NO in RAW264.7 cells activated by lipopolysaccharide, with IC50 values ranging from 3.6 to 32.2 μM. The structure–activity relationships of the fusarins are discussed herein.

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).

scholarly journals Stereoselective total syntheses of (±)-sinularene and (±)-5-epi-sinularene: a general intramolecular Diels–Alder approach to tricyclic sesquiterpenes

1985 ◽  
Vol 63 (4) ◽  
pp. 993-995 ◽  
Author(s):  
Kazimierz Antczak ◽  
John F. Kingston ◽  
Alex G. Fallis
Keyword(s):  
Double Bond ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Exocyclic Double Bond ◽  
Total Syntheses ◽  
Methyl Group ◽  
Secondary Hydroxyl ◽  
Selective Hydrogenolysis

Stereoselective total synthesis of (±)-sinularene and (±)-5-epi-sinularene are described. The sequence employs a "blocked" cyclopentadiene in which the cyclopropane unit also serves as a latent methyl group. Thus intramolecular [4 + 2] cycloaddition of the substituted methyl spiro[2.4]hepta-4,6-dien-1-yl)-2-pentenoate 11 affords 5-benzyloxy-6-isopropyl-8-carbomethoxytetracyclo[5.4.01,7.02,4.02,9]undec-10-ene (12) which after selective hydrogenolysis generates the tricyclo[4.4.01,6.02,8]decane (sinularene) ring system. Removal of the secondary hydroxyl function (Ph3P/CCl4/CH3CN; H2/Pd/C), reduction of the methyl ester (LiAlH4), and introduction of the exocyclic double bond (acetate pyrolysis, 550 °C) completes the synthesis of (±)-sinularene in 14 steps from cyclopentadiene. A parallel series of reactions employing the isopropyl epimer of 12 affords (±)-5-epi-sinularene.

scholarly journals Secondary Metabolites with Nitric Oxide Inhibition from Marine-Derived Fungus Alternaria sp. 5102

Marine Drugs ◽  
2020 ◽  
Vol 18 (8) ◽  
pp. 426 ◽  
Author(s):  
Senhua Chen ◽  
Yanlian Deng ◽  
Chong Yan ◽  
Zhenger Wu ◽  
Heng Guo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
2D Nmr ◽  
X Ray ◽  
X Ray Crystallography ◽  
Spectroscopic Analyses ◽  
Structure Activity ◽  
Ic50 Values ◽  
Alternaria Sp ◽  
Modified Mosher’S Method ◽  
Oxide Inhibition

Two new benzofurans, alternabenzofurans A and B (1 and 2) and two new sesquiterpenoids, alternaterpenoids A and B (3 and 4), along with 18 known polyketides (5−22), were isolated from the marine-derived fungus Alternaria sp. 5102. Their structures were elucidated on the basis of extensive spectroscopic analyses (1D and 2D NMR, HR-ESIMS, and ECD) and X-ray crystallography, as well as the modified Mosher’s method. Compounds 2, 3, 5, 7, 9–18, and 20–22 exhibited potent anti-inflammatory activity by inhibiting the production of NO in RAW264.7 cells activated by lipopolysaccharide with IC50 values in the range from 1.3 to 41.1 μM. Structure-activity relationships of the secondary metabolites were discussed.

The Structure of Polyisoprenes. II. The Structure of β-Gutta-Percha

1945 ◽  
Vol 18 (2) ◽  
pp. 280-283
Author(s):  
G. A. Jeffrey
Keyword(s):  
Molecular Structure ◽  
Double Bond ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Interatomic Distances ◽  
Methyl Group ◽  
X Ray ◽  
Gutta Percha ◽  
Qualitative Estimate

Abstract The x-ray diffraction data at present available from β-gutta-percha are shown to be insufficient to distinguish fine details of molecular structure. Since a qualitative estimate of the intensities on the fibre diagram can be adequately satisfied by a model having normal interatomic distances and valency angles, no evidence exists for the improbable distortion of the methyl group out of the plane of the double bond previously ascribed to the molecule.

Heterometallische Cluster durch ligandunterstützte Metallfragmentkondensation / Heterometallic Clusters by Ligand Assisted Metal Fragment Condensation

1991 ◽  
Vol 46 (9) ◽  
pp. 1169-1176 ◽  
Author(s):  
Wolfgang Rohde ◽  
Gert Fendesak
Keyword(s):  
Double Bond ◽  
Chelate Complexes ◽  
Heterometallic Clusters ◽  
X Ray ◽  
X Ray Crystallography ◽  
Inert Solvent ◽  
Fragment Condensation ◽  
Olefinic Double Bond ◽  
High Yields ◽  
Iron Fragment

Dicobalt complexes of 3-vinylpropargylic alcohol derivatives react with biscyclooctenetricarbonyliron to give new chelate complexes of the iron tricarbonyl fragment with the olefinic double bond and the alcohol oxygen atom bound to the iron fragment. These compounds react upon heating in an inert solvent to give FeCo-alkynyl cluster complexes in high yields. One of these compounds has been structurally characterized by X-ray crystallography.

Studies Directed Towards the Total Synthesis of Anticapsin. X-Ray Crystal-Structure of (1RS,2SR,4RS,5RS,6SR)-5-Hydroxy-2-phthalimido-1-trimethylsilyloxy-bicyclo[2.2.2]octane-2,6-carbolactone

1990 ◽  
Vol 43 (11) ◽  
pp. 1827 ◽  
Author(s):  
MJ Crossley ◽  
TW Hambley ◽  
AW Stamford
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Total Synthesis ◽  
Synthetic Approach ◽  
Hydrogen Atoms ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography ◽  
Relative Stereochemistry ◽  
Atomic Parameters

The relative stereochemistry of methyl 2-phthalimido-1- trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate (9) and its 5,6-epoxide (10), intermediates in a synthetic approach to the amino acid antibiotic anticapsin, were established by the TiCl4-mediated cyclization of (10) to the carbolactone (12); the structure of which was proved by single-crystal X-ray crystallography. Full-matrix least- squares refinement of all atomic parameters with individual isotropic thermal parameters for the hydrogen atoms by using 1446 reflections converged at R 0.036. Crystals of (12) are monoclinic, P21/c, a 12.342(3), b 12.239(2), c 13.405(3) Ǻ, β 99.34(2)°, Z 4.

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