ChemInform Abstract: Isomerization of Tinidazole Involving a Novel N-Alkyl Group Migration.

Examples of internally alkylated azuliporphyrins were prepared by MacDonald-type “3 + 1” condensations. 2-Methyl- and 2-ethylazulene reacted with an acetoxymethylpyrrole in the presence of an acid catalyst to give azulitripyrranes. Following cleavage of the terminal protective groups, condensation with a diformylpyrrole in the presence of hydrochloric acid and oxidation with ferric chloride afforded 21-alkylazuliporphyrins. An azulene dialdehyde similarly reacted with an [Formula: see text]-methyltripyrrane to generate a 23-methylazuliporphyrin. The products could only be isolated in protonated form and the free-base internally alkylated azuliporphyrins proved to be unstable. Nevertheless, the dications are highly diatropic and the internal alkyl group resonances were shifted upfield to beyond -3 ppm. Reaction of a 23-methylazuliporphyrin with palladium(II) acetate primarily afforded a palladium(II) complex with loss of the internal methyl substituent. However, two palladium(II) benzocarbaporphyrins were also identified that were formed by sequential oxidative ring contraction and methyl group migration. Internally alkylated azuliporphyrins provide new insights into the reactivity of the system and the results show that the introduction of alkyl substituents within porphyrinoid cavities greatly modifies the properties of these structures.

Download Full-text

Alkyl group migration in rhodium carbonyl dithiolates and the molecular structure of carbonyl(triphenylphosphine)(1-(ethylthio)maleonitrile-2-thiolato)rhodium, Rh(CO)(PPh3)(Et-mnt)

Inorganic Chemistry ◽

10.1021/ic50199a022 ◽

1979 ◽

Vol 18 (9) ◽

pp. 2438-2445 ◽

Cited By ~ 15

Author(s):

Chien-Hong Cheng ◽

Richard Eisenberg

Keyword(s):

Molecular Structure ◽

Alkyl Group ◽

Group Migration

Download Full-text

Unexpected Products from Mesoionic 1,3-Thiazinium and Oxazinium Olates: A Novel Access to 3,5-Diaryl-1,3-thiazine-2,4,6-trione and Alkoxy-3,5-diphenyl-3H-1,3-oxazine-2,6-dione Derivatives

Australian Journal of Chemistry ◽

10.1071/ch14095 ◽

2014 ◽

Vol 67 (9) ◽

pp. 1201 ◽

Cited By ~ 6

Author(s):

Mahboobeh Zahedifar ◽

Hassan Sheibani

Keyword(s):

Alkyl Group ◽

Room Temperature ◽

Group Migration

The condensation of (chlorocarbonyl)ketenes 1 with N-phenylthiocarbamates 2 and N-phenylcarbamates 6 is postulated to lead to the formation of unstable mesoionic 1,3-thiazinium 4-olates I or 1,3-oxazinium 4-olates II, respectively. At room temperature, appropriately substituted mesoionic 1,3-thiazinium 4-olates I eliminated the corresponding alkene with generation of 3,5-diaryl-1,3-thiazine-2,4,6-trione derivatives 3. However, the methoxy-substituted compound 5 was stable at room temperature at least for several weeks. In the case of the mesoionic1,3-oxazinium 4-olates II an alkyl group migration affords 4-alkoxy-3,5-diphenyl-3H-1,3-oxazine-2,6-diones 7.

Download Full-text

ChemInform Abstract: ALKYL GROUP MIGRATION IN RHODIUM CARBONYL DITHIOLATES AND THE MOLECULAR STRUCTURE OF CARBONYL(TRIPHENYLPHOSPHINE)(1-(ETHYLTHIO)MALEONITRILE-2-THIOLATO)RHODIUM, RH(CO)(PPH3)(ET-MNT)

Chemischer Informationsdienst ◽

10.1002/chin.197950316 ◽

1979 ◽

Vol 10 (50) ◽

Author(s):

C.-H. CHENG ◽

R. EISENBERG

Keyword(s):

Molecular Structure ◽

Alkyl Group ◽

Group Migration

Download Full-text

Enantioselective Aryl-Iodide-Catalyzed Wagner–Meerwein Rearrangements

10.26434/chemrxiv.12733592 ◽

2020 ◽

Author(s):

Hayden Sharma ◽

Katrina Mennie ◽

Eugene Kwan ◽

Eric Jacobsen

Keyword(s):

Asymmetric Catalysis ◽

Isotope Effect ◽

Reaction Mechanisms ◽

Alkyl Group ◽

Kinetic Isotope Effect ◽

Aryl Iodide ◽

Kinetic Isotope ◽

Conformational Properties ◽

Rearrangement Reactions ◽

Group Migration

We report a strategy for effecting catalytic, enantioselective carbocationic rearrangements through the intermediacy of alkyl iodanes as stereodefined carbocation equivalents. Asymmetric Wagner–Meerwein rearrangements of β-substituted styrenes are catalyzed by the C2-symmetric aryl iodide 1 to provide access to enantioenriched 1,3-difluorinated molecules possessing interesting and well-defined conformational properties. Hammett and kinetic isotope effect studies, in combination with computational investigations, reveal that two different mechanisms are operative in these rearrangement reactions, with the pathway depending on the identity of the migrating group. In reactions involving alkyl-group migration, intermolecular fluoride attack is product- and enantio-determining. In contrast, reactions in which aryl rearrangement occurs proceed through an enantiodetermining intramolecular 1,2-migration prior to fluorination. The fact that both pathways are promoted by the same chiral aryl iodide catalyst with high enantioselectivity provides a compelling illustration of generality across reaction mechanisms in asymmetric catalysis.

Download Full-text