Carbonyl group-containing organometallic intramolecular-coordination five-membered ring compounds

A study has been made of the ionization potentials (IP) of the carbonyl lone pair orbitals in a series of five-membered carbonyl ring compounds. CNDO/2 and INDO calculations have been performed on these molecules, and correlation of IP shifts with changes in molecular bonding is obtained.

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Carbocyclic Three- and Four-Membered Ring Compounds

10.1055/b-003-109677 ◽

1997 ◽

Keyword(s):

Membered Ring ◽

Ring Compounds

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Isomerization of the Isoprene Hydroxy Nitrates and Formation of Orthonitrite Compounds

10.26434/chemrxiv.8317127 ◽

2019 ◽

Author(s):

Gabriel da Silva

Keyword(s):

Hydroxy Group ◽

Peroxyl Radical ◽

Branching Fractions ◽

Membered Ring ◽

Low Energy ◽

Peroxyl Radicals ◽

Aerosol Formation ◽

Subsequent Removal ◽

Ring Compounds ◽

Group Migration

Atmospheric oxidation of isoprene produces significant yields of eight unique nitrate 11 compounds, each with a β- or δ-hydroxy group. These isoprene hydroxy nitrates (ISOPNs) 12 significantly impact upon global NOx budgets, O3 levels, and aerosol formation. 13 Uncertainties exist, however, in our understanding of ISOPN chemistry, particularly in their 14 yields from the reaction of isoprene peroxyl radicals with NO. This study describes novel 15 isomerization reactions of the ISOPNs, identified through the application of computational 16 chemistry techniques. These reactions produce saturated polycyclic orthonitrite compounds 17 via attack of the R–NO2 group on the vinyl moiety. For the δ-hydroxy nitrates, low-energy 18 isomerization pathways exist to six-membered ring compounds that are around 5 kcal mol-1 19 exothermic. These reactions proceed with barriers around 15 kcal mol-1 below the 20 respective peroxyl radical + NO reactants and yield orthonitrites that can further isomerize 21 to β-hydroxy ISOPNs. Moreover, the δ-hydroxy nitrates can directly interconvert with their β 22 substituted counterparts via NO3 group migration, with barriers that are lower yet. It follows 23 that β-hydroxy nitrates may be stabilized in the δ-hydroxy form, and vice versa. Moreover, 24 the lowest-energy pathway for dissociation of the δ-hydroxy ISOPNs is for the formation of 25 β-hydroxy alkoxyl radicals, and because of this established branching fractions between the 26 various isoprene peroxyl radicals may require re-evaluation. The results presented here also 27 suggest that ISOPNs may be stabilized to some extent in their saturated orthonitrite forms, 28 which has implications for both the total nitrate yield and for their subsequent removal by 29 OH, O3, and photolysis.<br><br>

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Low-valent dialkoxytitanium(ii): a useful tool for the synthesis of functionalized seven-membered ring compounds

Chemical Communications ◽

10.1039/d1cc00081k ◽

2021 ◽

Vol 57 (29) ◽

pp. 3603-3606

Author(s):

Florent Bodinier ◽

Youssouf Sanogo ◽

Janick Ardisson ◽

Marie-Isabelle Lannou ◽

Geoffroy Sorin

Keyword(s):

Grignard Reagent ◽

Membered Ring ◽

Ring Compounds ◽

Low Valent

Herein, we describe unprecedented access to all-carbon or heterocyclic seven-membered ring frameworks from 1,8-ene-ynes promoted by inexpensive low-valent titanium(ii) species, readily available from a combination of Ti(OiPr)4 and Grignard reagent.

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Enantioselective Functionalization of Prochiral Cyclobutanones and Cyclobutenones

Synlett ◽

10.1055/a-1493-9489 ◽

2021 ◽

Author(s):

Memg Wang ◽

Changxu Zhong ◽

Ping Lu

Keyword(s):

Asymmetric Synthesis ◽

Membered Ring ◽

Enantioselective Synthesis ◽

Ring Compounds ◽

Recent Advances ◽

Cyclobutane Derivatives

Enantioselective synthesis of cyclobutane derivatives is still a challenging topic in asymmetric synthesis. [2+2]-Cycloaddition and skeleton rearrangement are two primary strategies to this end. Recently, functionalization of cyclobutanones and cyclobutenones, which are readily available via [2+2]-cycloadditions as prochiral substrates, has emerged as a powerful tool to access versatile four-membered ring compounds. Herein, we summarize some recent advances in these areas from our and other groups.

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