Reaktionen mit Cyclobutendionen, XXXVII. Umsetzungen des (2,5‐Dimethoxyphenyl)phenyl‐ und des Diphenylcyclobutendions mit Diazoalkanen. Ein Beitrag zur Isomerie der möglichen 1‐Pyrazoline
Abstract:Umsetzungen des (2,IDimethoxyphenyl)phenyl-und des Diphenylcyclobutendions rnit Diazoalkanen.(2,5-Dimethoxyphcnyl)phenyIcyclobutendion (7) reagiert rnit Diazomethan in Benzol ausschlieb lich zu 3a-(2,5-Dimethoxyphenyl)-4methoxy-6-ox~6a-phenyl-3,3a,6,~-tetrahydrocyc~o~ntapyrazol @a). Dieses kann in Eisessig zum 2-Pyrazolin 9a umgelagert werden. Diphenylcyclobutendion (1) reagiert mit Diazoathan m zwei diastereomeren 1-Pyrazolinen 10 und 11. Beide ergeben in Eisessig das gleiche 2-Pyrazolin 12 sowie mit Acetylch… Show more
“…3-(4-Methoxyphenyl)-3-cyclobutene-1,2-dione (14e). Method C: yellow crystals; mp 156−158 °C dec (acetone), (lit 6a…”
Section: Methodsmentioning
confidence: 99%
“…Thus, 3,4-dichlorocyclobutenedione (squaric dichloride) (1) affords 3-aryl-4-chlorocyclobutenediones 3a or diarylcyclobutenediones 4 , depending upon the amount of catalyst (AlCl 3 ), the molar ratio of the educts, and the reaction conditions (Scheme ). − Accordingly, the 3-aryl-4-halogenocyclobutenediones 3a and 3b react with arenes 2 ‘ to give the diarylcyclobutenediones 4 . 2g, Monosubstituted cyclobutenediones such as 5 , on the other hand, behave as vinylogous aldehydes. They react with arenes in the presence of 1 equiv of AlCl 3 to give 2-hydroxy-2-cyclobuten-1-ones 6a and 6b . 2g,, 1 …”
The reaction of semisquaric chloride (7) with
arenes 2 has been investigated. In the presence
of
1.1 equiv of AlCl3 and in the temperature range of −15°
C to rt the arenes 2a-q afford the 4-aryl-3-chloro-2-hydroxy-2-cyclobuten-1-ones (chloroenols) 8a-q in
good yield. By contrast, 7 reacts with
1,4-dimethoxybenzene (2l) in boiling
CH2Cl2 to give a mixture of
(2,5-dimethoxyphenyl)cyclobutenedione (9a) (27% yield) and
bis(2,5-dimethoxyphenyl)cyclobutenedione
(10a) (8% yield). With 1,2,4-trimethoxybenzene (2r) in the presence of
trifluoroacetic acid is generated
(2,4,5-trimethoxyphenyl)cyclobutenedione (9b) in 21% yield. The
chloroenols 8 allow a series of valuable
transformation
reactions: with diazomethane the chloroenol methyl ethers 11
are generated, with chlorine the
3-aryl-4-chlorocyclobutenediones 12, and with bromine in
MeOH the 3-aryl-4-methoxycyclobutenediones 13. In DMSO or in acetone/H2O the
chloroenols 8 eliminate HCl, furnishing the
arylcyclobutenediones 14. In a mixture of
acetone-d
6/D2O/DCl are obtained
4-aryl-cyclobutenediones-3-d
15. For the latter two processes the
corresponding 3-aryl-4-chlorocyclobutane-1,2-diones
16 are postulated as intermediates. Thermolysis of the
chloroenols 8 and the chloroenol methyl
ethers 11 in refluxing m-xylene afforded the
3-chloro-1,2-dihydroxynaphthalenes 17 and the
3-chloro-1-hydroxy-2-methoxynaphthalenes 18,
respectively.
“…3-(4-Methoxyphenyl)-3-cyclobutene-1,2-dione (14e). Method C: yellow crystals; mp 156−158 °C dec (acetone), (lit 6a…”
Section: Methodsmentioning
confidence: 99%
“…Thus, 3,4-dichlorocyclobutenedione (squaric dichloride) (1) affords 3-aryl-4-chlorocyclobutenediones 3a or diarylcyclobutenediones 4 , depending upon the amount of catalyst (AlCl 3 ), the molar ratio of the educts, and the reaction conditions (Scheme ). − Accordingly, the 3-aryl-4-halogenocyclobutenediones 3a and 3b react with arenes 2 ‘ to give the diarylcyclobutenediones 4 . 2g, Monosubstituted cyclobutenediones such as 5 , on the other hand, behave as vinylogous aldehydes. They react with arenes in the presence of 1 equiv of AlCl 3 to give 2-hydroxy-2-cyclobuten-1-ones 6a and 6b . 2g,, 1 …”
The reaction of semisquaric chloride (7) with
arenes 2 has been investigated. In the presence
of
1.1 equiv of AlCl3 and in the temperature range of −15°
C to rt the arenes 2a-q afford the 4-aryl-3-chloro-2-hydroxy-2-cyclobuten-1-ones (chloroenols) 8a-q in
good yield. By contrast, 7 reacts with
1,4-dimethoxybenzene (2l) in boiling
CH2Cl2 to give a mixture of
(2,5-dimethoxyphenyl)cyclobutenedione (9a) (27% yield) and
bis(2,5-dimethoxyphenyl)cyclobutenedione
(10a) (8% yield). With 1,2,4-trimethoxybenzene (2r) in the presence of
trifluoroacetic acid is generated
(2,4,5-trimethoxyphenyl)cyclobutenedione (9b) in 21% yield. The
chloroenols 8 allow a series of valuable
transformation
reactions: with diazomethane the chloroenol methyl ethers 11
are generated, with chlorine the
3-aryl-4-chlorocyclobutenediones 12, and with bromine in
MeOH the 3-aryl-4-methoxycyclobutenediones 13. In DMSO or in acetone/H2O the
chloroenols 8 eliminate HCl, furnishing the
arylcyclobutenediones 14. In a mixture of
acetone-d
6/D2O/DCl are obtained
4-aryl-cyclobutenediones-3-d
15. For the latter two processes the
corresponding 3-aryl-4-chlorocyclobutane-1,2-diones
16 are postulated as intermediates. Thermolysis of the
chloroenols 8 and the chloroenol methyl
ethers 11 in refluxing m-xylene afforded the
3-chloro-1,2-dihydroxynaphthalenes 17 and the
3-chloro-1-hydroxy-2-methoxynaphthalenes 18,
respectively.
R e c e i v e d 2 0 / 7 / 7 6 -Accepted 1 3 / 9 / 7 6 .
RESUMEDans c e travail, n o u s a v o n s synth6tis6 plusieurs pyrazolines-2 par isom€-risation, e n milieu acide, des pyrazolines-1 correspondantes. L'Otude radiocristallographique et spectroscopique d e s pyrazolines-2 consid6-r€es demonere la n o n planeit€ d u cycle. L'dpim€risation d e c e s compos6s. e n milieu acide. fournit e n m a j o r i t 6 l'6pimire trans.
Diphenylcyclobutendion (1 a) reagiert rnit den Methylenphosphoranen 4a -z zu substituierten 4-Methylen-2,3-diphenyl-2-cyclobuten-l-onen 5a -p. t -z bzw. 5u'-z', deren Struktur spektroskopisch gesichert wird. Die Synthese des Grundkorpers 5 r gelingt nicht. Die Wittig-Reaktion am (2,5-Dimethoxyphenyl)phenylcyclobutendion (1 d) mit 4u verlauft annahernd stereoselektiv zu 9D.
Reactions of Cyclobutenediones, XLll ')
Reactions of Dipbenylcyclobutenedione with MetbylenephospboranesDiphenylcyclobutenedione (1 a) reacts with the methylenephosphoranes 4a-2 to give the substituted 4-methylene-2,3-diphenyl-2-cyclobuten-l-ones 5a -p, t -z and 5u' -2'. Structural proof of the products is given by spectroscopic methods. The unsubstituted compound 5r is not obtained. Wittig reaction of (2,5-dimethoxyphenyl)phenylcyclobutenedione (1 d) with 4u proceeds nearly stereoselectively to give 9D.Cyclobutendione des Typs 1 a -c sind chemisch durch ihren vinylogen Keton-bzw.Aldehydcharakter gekennzeichnet und daher leicht nucleophilen Reaktionen zuganglich. Wahrend die Einwirkung von Verbindungen rnit funktionellen N-bzw. S-Gruppen in jungster Zeit 3 * 4 ) besonders intensiv untersucht worden ist, blieben Additionen von C-Nucleophilen auf Aromaten 'I, CH-acide Verbindungen und Pyridinium-Betaine ' ) beschrankt. 1 a reagiert zudem rnit 1,2-Bis(phosphoranylidenmethyl)-Verbindungen zu Thiophen-, naphthalin-und anthracen-anellierten Abkommlingen 2 a -c des Diphenylcyclobutadiens ' . ').Bei der letztgenannten Umsetzung wird zusiitzlich die Verbindung 3 als Hauptprodukt erhalten').
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
