scholarly journals Formal Synthesis of (+)-Brefeldin A:  Application of a Zinc-Mediated Ring Expansion Reaction

2007 ◽  
Vol 72 (12) ◽  
pp. 4390-4395 ◽  
Author(s):  
Weimin Lin ◽  
Charles K. Zercher
Keyword(s):  
Brefeldin A ◽  
Ring Expansion ◽  
Formal Synthesis ◽  
Ring Expansion Reaction

Unusual Ring-Expansion Reaction of Polyfluorinated Norbornenoxetanes

Synthesis ◽  
2007 ◽  
Vol 2007 (9) ◽  
pp. 1349-1354 ◽  
Author(s):  
Viacheslav Petrov ◽  
Will Marshall
Keyword(s):  
Ring Expansion ◽  
Ring Expansion Reaction

Synthesis and Ring Cyclization - Expansion - Contraction Reactions of Some New 2,2-Disubstituted Indan-1,3-diones and Related Compounds

2006 ◽  
Vol 59 (1) ◽  
pp. 59 ◽  
Author(s):  
Craig J. Roxburgh ◽  
Lee Banting
Keyword(s):  
Catalytic Hydrogenation ◽  
Pyridine Ring ◽  
Functional Group ◽  
Chemical Properties ◽  
Ring Expansion ◽  
Ring Structure ◽  
Side Reactions ◽  
The Third ◽  
Ring Expansion Reaction ◽  
Related Compounds

We have found that the hydrochloride of 2-phenyl-2-[2-(2-piperidyl)ethyl]-4,5,6,7-tetrahydroindan-1,3-dione 1 possesses marked analgesic activity (100% inhibition referenced to codeine) and report, as part of an extensive synthetic program, the synthesis of 38 new and structurally related compounds. Selective catalytic hydrogenation of the pyridine ring of 2-phenyl-2-[2-(2-pyridyl)ethyl]-indan-1,3-dione 2 yields the nine-membered nitrogen-containing heterocycle 6 by a novel ring cyclization–expansion reaction. The structural and functional group parameters required for this novel ring-expansion reaction have been extensively and thoroughly investigated through the synthesis of a series of structurally related compounds; principally by modification, substitution, and replacement of the various functionality contained within 2. In addition, we report the synthesis of a series of new 2-methyl-2-(ω-N-phthalimidoalkyl)-indan-1,3-diones 41, 45, and 53, two of which, like the parent 2-phenyl substituted indan-1,3-dione 2, also undergo a novel ring cyclization–expansion reaction to yield eight- and nine-membered nitrogen-containing rings. However, in these cases, further transannular reactions occur to produce the new 5,5- and 5,6-ring-fused nitrogen-containing heterocycles 44, 48 and 51, 52. Hydrazinolysis of the third, 2-methyl-2-(4-N-phthalimidobutyl)-indan-1,3-dione yields the new azepine-containing ring structure 56 by direct cyclization. Furthermore, some interesting and unexpected chemical properties of the final compounds, which include selective and non-selective pyridine-ring hydrogenations and a few unexpected side reactions, are described.

ChemInform Abstract: Enantioconvergent Formal Synthesis of Brefeldin A via Sakai-Catalyzed Cyclization.

ChemInform ◽  
2010 ◽  
Vol 30 (38) ◽  
pp. no-no
Author(s):  
Pierre Ducray ◽  
Bernard Rousseau ◽  
Charles Mioskowski
Keyword(s):  
Brefeldin A ◽  
Formal Synthesis

Synthesis, Optical Properties, Structures and Molecular Orbital Calculations of Subazaporphyrins, Subphthalocyanines, Subnaphthalocyanines and Related Compounds

1999 ◽  
Vol 03 (06) ◽  
pp. 453-467 ◽  
Author(s):  
NAGAO KOBAYASHI
Keyword(s):  
Molecular Orbital ◽  
Magnetic Circular Dichroism ◽  
Soret Band ◽  
Ring Expansion ◽  
Molecular Orbital Calculations ◽  
Mo Calculations ◽  
Key Points ◽  
Adsorption Data ◽  
Ring Expansion Reaction ◽  
Related Compounds

The synthesis of and spectroscopic data on subazaporphyrins, subphthalocyanines, subnaphthalocyanines and their related compounds reported to date are summarized, together with the results of molecular orbital (MO) calculations from our laboratory. Thus the problems and key points in the synthesis of these subazamacrocycles and their electronic absorption and magnetic circular dichroism (MCD) spectra are discussed, together with those of the monosubstituted-type low-symmetrical phthalocyanines obtained by their ring expansion reaction. The Q bands of these subazamacrocycles are orbitally doubly degenerate, and in the Soret band region, three transitions to the orbitally degenerate state are found. The MO calculations suggest that the HOMO levels destabilize considerably while the LUMO levels change slightly with increasing size of the π system. In addition, the electronic adsorption data are reproduced by the calculation only when the two pyrrole hydrogens in the monosubstituted-type phthalocyanines are assumed to be linked to the two pyrrole nitrogens along the short axis.

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