Methylene Meldrum’s Acid Derivatives of Indoxyl and Their Cyclization Reactions under Flash Vacuum Pyrolysis Conditions

Condensation of 4-methoxy-2,6-dimethylbenzaldehyde with Meldrum's acid, and flash vacuum pyrolysis of the condensation product (12) gave in almost quantitative yield 7-methoxy-5-methyl-2-naphthol (9). This naphthol is a precursor of the title 1-carboxylic acid (6), an intercalating moiety of enediyne and other antibiotics.

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Methyleneketenes and methylenecarbenes. XV. A new synthesis of ruscodibenzofuran

Australian Journal of Chemistry ◽

10.1071/ch9801817 ◽

1980 ◽

Vol 33 (8) ◽

pp. 1817 ◽

Cited By ~ 13

Author(s):

RFC Brown ◽

CM Jones

Keyword(s):

Condensation Product ◽

Meldrum's Acid ◽

Meldrum’S Acid ◽

Flash Vacuum Pyrolysis ◽

Vacuum Pyrolysis ◽

New Synthesis

Ruscodibenzofuran (2-acetyl-6,9-dimethyldibenzofuran-3-ol) has been synthesized by condensation of 2,4,7-trimethylbenzofuran-3-carbaldehyde with Meldrum's acid, flash vacuum pyrolysis of the condensation product (8), and overall C-acetylation of the resulting 6,9-dimethylbenzofuran- 3-ol.

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Cyclopentadienylideneethenone: Pyrolytic Generation and Argon Matrix Infrared Spectroscopic Study

Australian Journal of Chemistry ◽

10.1071/ch9891321 ◽

1989 ◽

Vol 42 (8) ◽

pp. 1321 ◽

Cited By ~ 15

Author(s):

RFC Brown ◽

NR Browne ◽

KJ Coulston ◽

FW Eastwood ◽

MJ Irvine ◽

...

Keyword(s):

Carbonyl Group ◽

Alder Reaction ◽

Infrared Spectroscopic Study ◽

Meldrum's Acid ◽

Meldrum’S Acid ◽

Argon Matrix ◽

Flash Vacuum Pyrolysis ◽

Matrix Isolation Spectroscopy ◽

Vacuum Pyrolysis ◽

Argon Matrices

Two previously reported pyrolytic precursors for cyclopentadienylideneethenone (4) and benzyne produced two strong infrared bands attributable to ketene type compounds when their pyrolysates were examined by argon matrix isolation spectroscopy. To determine which band should be assigned to (4), four new precursors for (4) and benzyne and two analogues labelled with 13C at the carbonyl group have been synthesized. Precursors (8) and (14) are respectively a caged system and a bridged ,system bearing a mixed anhydride with trifluoroacetic acid. Flash vacuum pyrolysis of (8) and (14) at 600-700 with trapping at 77 K gave pyrolysates which contained biphenylene. Pyrolysis of (8) and (14) at 600-700�; in a stream of argon followed by deposition as an argon matrix at about 10 K showed that both produced a pyrolysate absorbing at 2089 cm-1 assigned to (4). Precursors (24) and (25) and the previously reported (18) and (27) are Meldrum's acid derivatives designed to yield the hypothetical cyclopentadienylidene Meldrum's acid (19) by cage fission or retro-Diels-Alder reaction. They all gave their biphenylene on flash vacuum pyrolysis at 600-700 � and their pyrolysates in argon matrices showed absorption both at 2089 cm-1 due to (4) and at 2225 cm-1 due to an unidentified ketene. The frequency shift resulting from substitution of 13C in the carbonyl group (52 cm-l) is in accordance with the assignment of the 2089 cm-1 band to (4). The pyrolysates from precursors 8a), (14), (18a), (25)and (27) were allowed to react with methanol and the resulting mixtures were hydrogenated. In all cases methyl cyclopentylacetate was obtained.

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Zur Reaktion von 2,3-Dihydro-1,3-diisopropy1-4,5-imidazol-2-yliden mit Bromderivaten der Meldrumsäure [1, 2] / On the Reaction of 2,3-Dihydro-1,3-diisopropy1-4,5-dimethylimidazol-2-ylidene with Bromine Derivatives of Meldrum’s Acid [1, 2]

Zeitschrift für Naturforschung B ◽

10.1515/znb-2004-0202 ◽

2004 ◽

Vol 59 (2) ◽

pp. 129-133 ◽

Cited By ~ 5

Author(s):

Norbert Kuhn ◽

Ahmed Al-Sheikh ◽

Simon Schwarz ◽

Manfred Steimann

Keyword(s):

Crystal Structure ◽

Ion Pairs ◽

Imidazolium Salts ◽

Meldrum's Acid ◽

Meldrum’S Acid ◽

Derivatives Of ◽

Meldrum's Acid Derivatives

The Imidazolium salts [ImH][MelBr] (7) and [ImBr][MelBr] (8) have been obtained from the carbene Im (5) and the Meldrum’s acid derivatives MelHBr (3) and MelBr2 (4). The crystal structure analyses of 7 and 8 reveal the presence of ion pairs linked by short OH (7: 2.163 Å ) and OBr (8: 2.872 Å ) contacts.

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