Details
| Original language | English |
|---|---|
| Pages (from-to) | 182-190 |
| Number of pages | 9 |
| Journal | Chemistry - a European journal |
| Volume | 2 |
| Issue number | 2 |
| Publication status | Published - Feb 1996 |
| Externally published | Yes |
Abstract
The tricarbonylchromium complex 3 of 1,2-dioxobenzocyclobutene (1) is easily prepared by hydrolysis of diacetal 4. Complex 3 stereoselectively undergoes both single and double nucleophilic addition reactions at the keto groups. As a consequence, addition of excess alkenyllithium to 3 gives rise to a dianionic oxy-Cope rearrangement yielding benzocyclooctenedione complexes with good diastereoselectivity. Trapping of the bis(enolate) intermediate with chlorotrimethylsilane gives bis(enolether) 23. Subsequent addition of two different alkenyllithium derivatives yields the asymmetrically substituted rearrangement product 15. To some extent, dependent on the method of hydrolysis, an intramolecular aldol addition follows the dianionic oxy-Cope rearrangement. This results in the formation of benzoanellated bicyclo[3.3.0]octane derivatives and, in the case of 1-cyclopentenyllithium as the alkenylmetal, in the tetraquinane system 19. The trans-anellation of one of the cyclopentane rings in trans-20 has been verified by an X-ray structural analysis. The highly substituted rearrangement product 21/22 is formed only in small yield; in solution the bis(enol) tautomeric form 22 is favored over diketone 21.
Keywords
- Asymmetric syntheses, Chromium complexes, Diones, Oxy-Cope rearrangements, Polycycles
ASJC Scopus subject areas
- Chemical Engineering(all)
- Catalysis
- Chemistry(all)
- Organic Chemistry
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In: Chemistry - a European journal, Vol. 2, No. 2, 02.1996, p. 182-190.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Tricarbonyl(η6-1,2-dioxobenzocyclobutene)chromium(0)
T2 - Preparation, Nucleophilic Addition Studies and Syntheses of Complex Polycyclic Systems by Dianionic Oxy-Cope Rearrangement
AU - Brands, Michael
AU - Wey, Hans G.
AU - Bruckmann, Joachim
AU - Krüger, Carl
AU - Butenschön, Holger
PY - 1996/2
Y1 - 1996/2
N2 - The tricarbonylchromium complex 3 of 1,2-dioxobenzocyclobutene (1) is easily prepared by hydrolysis of diacetal 4. Complex 3 stereoselectively undergoes both single and double nucleophilic addition reactions at the keto groups. As a consequence, addition of excess alkenyllithium to 3 gives rise to a dianionic oxy-Cope rearrangement yielding benzocyclooctenedione complexes with good diastereoselectivity. Trapping of the bis(enolate) intermediate with chlorotrimethylsilane gives bis(enolether) 23. Subsequent addition of two different alkenyllithium derivatives yields the asymmetrically substituted rearrangement product 15. To some extent, dependent on the method of hydrolysis, an intramolecular aldol addition follows the dianionic oxy-Cope rearrangement. This results in the formation of benzoanellated bicyclo[3.3.0]octane derivatives and, in the case of 1-cyclopentenyllithium as the alkenylmetal, in the tetraquinane system 19. The trans-anellation of one of the cyclopentane rings in trans-20 has been verified by an X-ray structural analysis. The highly substituted rearrangement product 21/22 is formed only in small yield; in solution the bis(enol) tautomeric form 22 is favored over diketone 21.
AB - The tricarbonylchromium complex 3 of 1,2-dioxobenzocyclobutene (1) is easily prepared by hydrolysis of diacetal 4. Complex 3 stereoselectively undergoes both single and double nucleophilic addition reactions at the keto groups. As a consequence, addition of excess alkenyllithium to 3 gives rise to a dianionic oxy-Cope rearrangement yielding benzocyclooctenedione complexes with good diastereoselectivity. Trapping of the bis(enolate) intermediate with chlorotrimethylsilane gives bis(enolether) 23. Subsequent addition of two different alkenyllithium derivatives yields the asymmetrically substituted rearrangement product 15. To some extent, dependent on the method of hydrolysis, an intramolecular aldol addition follows the dianionic oxy-Cope rearrangement. This results in the formation of benzoanellated bicyclo[3.3.0]octane derivatives and, in the case of 1-cyclopentenyllithium as the alkenylmetal, in the tetraquinane system 19. The trans-anellation of one of the cyclopentane rings in trans-20 has been verified by an X-ray structural analysis. The highly substituted rearrangement product 21/22 is formed only in small yield; in solution the bis(enol) tautomeric form 22 is favored over diketone 21.
KW - Asymmetric syntheses
KW - Chromium complexes
KW - Diones
KW - Oxy-Cope rearrangements
KW - Polycycles
UR - http://www.scopus.com/inward/record.url?scp=0000575353&partnerID=8YFLogxK
U2 - 10.1002/chem.19960020210
DO - 10.1002/chem.19960020210
M3 - Article
AN - SCOPUS:0000575353
VL - 2
SP - 182
EP - 190
JO - Chemistry - a European journal
JF - Chemistry - a European journal
SN - 0947-6539
IS - 2
ER -