Taxamycins: a new enediyne family with synthetic and biological potential

1995 ◽  
Vol 73 (12) ◽  
pp. 2253-2262 ◽  
Author(s):  
Yee-Fung Lu ◽  
Curtis W. Harwig ◽  
Alex G. Fallis
Keyword(s):  
Building Blocks ◽  
Membered Ring ◽  
Selective Removal ◽  
Ring Closure ◽  
Trimethylsilyl Group ◽  
Biological Potential

The Pd(0) based synthesis of two disilyl synthons (Z-1-trimethylsilyl-6-tert-butyldiphenylsilylhex-3-ene-1,5-diyne (18) and Z-1-trimethylsilyl-6-triisopropylsilylhex-3-ene-1,5-diyne (19)) and the selective removal of the trimethylsilyl group (K2CO3, MeOH) to afford 24 and 25 is described. These building blocks are employed in the construction of the taxamycin-12 compound 38 (16,17,18-trimethyl-2-methyloxymethoxy-9-hydroxybicyclo[9.3.1]pentadec-5-ene-3,7-diyne). The final ring closure to the 12-membered ring utilizes an intramolecular Cr–Ni mediated condensation of the iodoalkyne 37 (1,3,3-trimethyl-2-(2-oxoethyl)-4-(Z-1-methyloxymethoxy-7-iodohept-4-ene-2,6-diynyl)cyclohexene). Keyword: cancer, enediynes, synthesis, Pd(0) coupling.

Conjugated oligomers incorporating azulene building blocks – seven- vs. five-membered ring connectivity

2014 ◽  
Vol 5 (11) ◽  
pp. 4483-4489 ◽  
Author(s):  
Elizabeth Amir ◽  
Masahito Murai ◽  
Roey J. Amir ◽  
John S. Cowart ◽  
Michael L. Chabinyc ◽  
...  
Keyword(s):  
Building Blocks ◽  
Membered Ring ◽  
Synthesis And Characterization ◽  
Conjugated Oligomers

The properties of isomeric azulene derivatives based on 7- versus 5-membered ring substitution were examined by the synthesis and characterization of well-defined electroactive oligomers.

Organometallic Complexes Containing a Co−N−C Three-Membered Ring:  Factors Affecting the Dynamic of the Ring Closure

2003 ◽  
Vol 22 (12) ◽  
pp. 2486-2491 ◽  
Author(s):  
Renata Dreos ◽  
Alessandro Felluga ◽  
Giorgio Nardin ◽  
Lucio Randaccio ◽  
Giovanni Tauzher
Keyword(s):  
Membered Ring ◽  
Organometallic Complexes ◽  
Ring Closure ◽  
Factors Affecting

Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

1988 ◽  
Vol 66 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Adrian L. Schwan ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
Hydrolysis Product ◽  
Sigmatropic Rearrangement ◽  
Membered Ring ◽  
Ring Closure ◽  
Experimental Results ◽  
First Order ◽  
Ring Opening Reaction ◽  
Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

Synthesis and characterization of the new tin borate SnB8O11(OH)4

2018 ◽  
Vol 73 (5) ◽  
pp. 337-348 ◽  
Author(s):  
Sandra Schönegger ◽  
Klaus Wurst ◽  
Gunter Heymann ◽  
Andreas Schaur ◽  
Andreas Saxer ◽  
...  
Keyword(s):  
Hydrothermal Process ◽  
Building Blocks ◽  
Membered Ring ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermoanalytical Investigations ◽  
Hydrogen Bond Interactions ◽  
Simple Hydrothermal Process

AbstractA new tin(II) borate with the composition SnB8O11(OH)4 was synthesized by a simple hydrothermal process. It crystallizes in the centrosymmetric monoclinic space group P21/n (no. 14) with the lattice parameters a=790.1(1), b=1402.2(2), c=994.8(1) pm, and β=90.40(5)° (Z=4). The new compound SnB8O11(OH)4 is isotypic to PbB8O11(OH)4 and isostructural to BaB8O11(OH)4. The borate layers are built up from fundamental building blocks (FBBs) with the composition [B8O11(OH)4]2−. Four of these FBBs form a nine-membered ring wherein the Sn2+ cations are located. These boron-oxygen layers are further connected by O–H···O hydrogen bond interactions. The characterization of SnB8O11(OH)4 is based on single-crystal X-ray diffraction data, vibrational spectroscopy, DFT calculations, and thermoanalytical investigations including high temperature powder XRD.

Studies on double acylation of aromatic hydrocarbons. XI. A total synthesis of 5,6-Dihydro-4H-benz[de]anthracene

1972 ◽  
Vol 25 (7) ◽  
pp. 1521 ◽  
Author(s):  
A Rahman ◽  
BM Vuano ◽  
NM Rodriguez
Keyword(s):  
Total Synthesis ◽  
Propionic Acid ◽  
Intramolecular Cyclization ◽  
Butyric Acid ◽  
Aromatic Hydrocarbons ◽  
Dibasic Acid ◽  
Membered Ring ◽  
Ring Closure ◽  
Partial Synthesis

Starting from ethyl 3-(1-naphthyl)propionate (1), the dibasic acid 4-(4-carboxy-ethyl-I-naphthyl)butyric acid (3) was prepared, which served as a key compound for the synthesis of 5,6-dihydro-4H-benz[de]anthraoene (6) by a double intramolecular cyclization. The monocyolization of the dibasic acid (3) gave rise by a preferential six-membered ring closure, to 3-(1-oxo-1,2,3,4-tetrahydro-9-phenanthryl)propionic acid (7). A partial synthesis of 5,6-dihydro-4H-benz[de]anthracene (6), by succinoylation of perinaphthane followed by usual synthetic steps, is reported as confirmatory evidence of the identity of (6) obtained by double cyclization of the diacid. Some aspects of the orientation of intramolecular acylation are discussed.

Massenspektrometrische Untersuchungen an Borchelaten der Pyridin- und Chinolin-Reihe und deren N-Oxiden / Mass Spectrometric Investigations on Boron Chelates of the Pyridine and Quinoline Type and their N-Oxides

1973 ◽  
Vol 28 (7-8) ◽  
pp. 440-445 ◽  
Author(s):  
Eberhard Hohaus ◽  
Wolfgang Riepe
Keyword(s):  
Carboxylic Acid ◽  
Mass Spectra ◽  
Membered Ring ◽  
Mass Spectrometric ◽  
Ring Closure ◽  
Boron Chelates ◽  
Boron Chelate

Mass spectra of chelate-6-rings (N-oxide-chelates) are similar to those of comparable chelate-5-rings after elimination of oxygen from the fragment ion (M-C6H5). It is assumed that the fragment ion [(M-C6H5)-O] exists as a five-membered ring.However, there are two exceptions which are: The diphenyl boron chelate of pyridine-2-carboxylic acid anilide N-oxide with O-B-O-coordination and the difluorine boron chelate of 8-hydroxyquinoline N-oxide. The stable fragment OBX (X = C6H5F) is eliminated directly from the fragment ion (M-X). It is assumed the ring closure in [(M-X)-O] obviously is less favoured. The preparation of both 5-ring-chelates using the components is impossible, too.

Synthesis of 5-/10-Membered Ring Analogues of the Dienediyne Core of Neocarzinostatine Chromophore by Palladium(0)-Mediated Ring-Closure Reaction

2006 ◽  
Vol 1996 (4) ◽  
pp. 447-456 ◽  
Author(s):  
Jean Suffert ◽  
Estelle Abraham ◽  
Stéphane Raeppel ◽  
Reinhard Brückner
Keyword(s):  
Membered Ring ◽  
Ring Closure
Sign in / Sign up

Export Citation Format

Share Document