Details
| Original language | English |
|---|---|
| Pages (from-to) | 93-113 |
| Number of pages | 21 |
| Journal | European Journal of Organic Chemistry |
| Issue number | 1 |
| Publication status | Published - 14 Dec 2000 |
Abstract
Dianionic oxy Cope rearrangements have been shown to take place at low temperature upon syn double addition of alkenyllithium derivatives to cyclobutanedione compounds such as benzocyclobutenedione chromium complex 1 or squaric acid esters. In order to obtain some insight into the more general applicability of this type of reaction sequence beyond these special cases, a number of 1,2-diketones were treated with vinyllithium. The diketones tested include benzil derivatives, aliphatic acyclic 1,2-diketones, ortho-quinones, and cyclic aliphatic 1,2-diketones. With benzil and heterobenzil derivatives, the desired double addition/dianionic oxy Cope rearrangement was found to take place at low temperature, leading to 1,6-diketones and their intramolecular aldol adducts in up to 80% overall yield. With acyclic aliphatic 1,2-diketones as substrates, this reaction sequence was also found, albeit with somewhat lower yields and requiring higher temperatures than in the benzil cases. A brief investigation of the intramolecular aldol adduct/1,6-hexanedione equilibrium indicated that the preferential formation of intramolecular aldol adducts at lower temperatures and at shorter reaction times appears to be the result of kinetic reaction control, whereas the preference for 1,6-diketones at higher temperatures is caused by thermodynamic reaction control, ortho-Quinones reacted with vinyllithium only by addition; no dianionic oxy Cope rearrangement was observed. This was also the case for most aliphatic cyclic diketones; however, in the case of 1,2-indanedione, rearrangement products were obtained in moderate yield at elevated reaction temperatures.
Keywords
- Aldol reactions, Dianionic oxy Cope rearrangement, Ketones, Pericyclic reactions, Rearrangements
ASJC Scopus subject areas
- Chemistry(all)
- Physical and Theoretical Chemistry
- Chemistry(all)
- Organic Chemistry
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In: European Journal of Organic Chemistry, No. 1, 14.12.2000, p. 93-113.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Reactions of 1,2-diketones with vinyllithium
T2 - Addition reactions and dianionic oxy Cope rearrangements of cyclic and acyclic substrates
AU - Clausen, Christian
AU - Wartchow, Rudolf
AU - Butenschön, Holger
PY - 2000/12/14
Y1 - 2000/12/14
N2 - Dianionic oxy Cope rearrangements have been shown to take place at low temperature upon syn double addition of alkenyllithium derivatives to cyclobutanedione compounds such as benzocyclobutenedione chromium complex 1 or squaric acid esters. In order to obtain some insight into the more general applicability of this type of reaction sequence beyond these special cases, a number of 1,2-diketones were treated with vinyllithium. The diketones tested include benzil derivatives, aliphatic acyclic 1,2-diketones, ortho-quinones, and cyclic aliphatic 1,2-diketones. With benzil and heterobenzil derivatives, the desired double addition/dianionic oxy Cope rearrangement was found to take place at low temperature, leading to 1,6-diketones and their intramolecular aldol adducts in up to 80% overall yield. With acyclic aliphatic 1,2-diketones as substrates, this reaction sequence was also found, albeit with somewhat lower yields and requiring higher temperatures than in the benzil cases. A brief investigation of the intramolecular aldol adduct/1,6-hexanedione equilibrium indicated that the preferential formation of intramolecular aldol adducts at lower temperatures and at shorter reaction times appears to be the result of kinetic reaction control, whereas the preference for 1,6-diketones at higher temperatures is caused by thermodynamic reaction control, ortho-Quinones reacted with vinyllithium only by addition; no dianionic oxy Cope rearrangement was observed. This was also the case for most aliphatic cyclic diketones; however, in the case of 1,2-indanedione, rearrangement products were obtained in moderate yield at elevated reaction temperatures.
AB - Dianionic oxy Cope rearrangements have been shown to take place at low temperature upon syn double addition of alkenyllithium derivatives to cyclobutanedione compounds such as benzocyclobutenedione chromium complex 1 or squaric acid esters. In order to obtain some insight into the more general applicability of this type of reaction sequence beyond these special cases, a number of 1,2-diketones were treated with vinyllithium. The diketones tested include benzil derivatives, aliphatic acyclic 1,2-diketones, ortho-quinones, and cyclic aliphatic 1,2-diketones. With benzil and heterobenzil derivatives, the desired double addition/dianionic oxy Cope rearrangement was found to take place at low temperature, leading to 1,6-diketones and their intramolecular aldol adducts in up to 80% overall yield. With acyclic aliphatic 1,2-diketones as substrates, this reaction sequence was also found, albeit with somewhat lower yields and requiring higher temperatures than in the benzil cases. A brief investigation of the intramolecular aldol adduct/1,6-hexanedione equilibrium indicated that the preferential formation of intramolecular aldol adducts at lower temperatures and at shorter reaction times appears to be the result of kinetic reaction control, whereas the preference for 1,6-diketones at higher temperatures is caused by thermodynamic reaction control, ortho-Quinones reacted with vinyllithium only by addition; no dianionic oxy Cope rearrangement was observed. This was also the case for most aliphatic cyclic diketones; however, in the case of 1,2-indanedione, rearrangement products were obtained in moderate yield at elevated reaction temperatures.
KW - Aldol reactions
KW - Dianionic oxy Cope rearrangement
KW - Ketones
KW - Pericyclic reactions
KW - Rearrangements
UR - http://www.scopus.com/inward/record.url?scp=0035132480&partnerID=8YFLogxK
U2 - 10.1002/1099-0690(200101)2001:1<93::AID-EJOC93>3.0.CO;2-X
DO - 10.1002/1099-0690(200101)2001:1<93::AID-EJOC93>3.0.CO;2-X
M3 - Article
AN - SCOPUS:0035132480
SP - 93
EP - 113
JO - European Journal of Organic Chemistry
JF - European Journal of Organic Chemistry
SN - 1434-193X
IS - 1
ER -