Addition and Ring Expansion Reactions of Tricarbonyl-(1,2-dioxobenzocyclobutene)chromium(0) with Carbon Nucleophiles: Unexpected Formation of Benzocycloheptene Derivatives and the First Head-to-Head Coupling of Two Methoxyallene Molecules

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OriginalspracheEnglisch
Seiten (von - bis)2719-2727
Seitenumfang9
FachzeitschriftEuropean Journal of Organic Chemistry
Ausgabenummer12
PublikationsstatusVeröffentlicht - 23 Dez. 1998

Abstract

Addition of carbon nucleophiles to (benzocyclobutenedione)tricarbonylchromiuni(0) (4) results in the formation of exo mono- and diadducts as well as 1,2-diketones as the consequence of proximal ring-opening reactions. In one case the unexpected formation of benzocycloheptenedione complexes is observed. Treatment of 4 with an excess of 1-ethoxy-1-lithioethene gives the product of a dianionic oxy-Cope rearrangement followed by an intramolecular aldol addition. This is also the case with lithiated methoxyallene, and as the result the first head-to-head coupling product 12 of two methoxyallene molecules is isolated in good yield. 12 is used as a diene in Diels-Alder cycloadditions, and its molecular structure is compared to that of the similar molecule 13, lacking the two exo methylene substitutents.

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title = "Addition and Ring Expansion Reactions of Tricarbonyl-(1,2-dioxobenzocyclobutene)chromium(0) with Carbon Nucleophiles: Unexpected Formation of Benzocycloheptene Derivatives and the First Head-to-Head Coupling of Two Methoxyallene Molecules",
abstract = "Addition of carbon nucleophiles to (benzocyclobutenedione)tricarbonylchromiuni(0) (4) results in the formation of exo mono- and diadducts as well as 1,2-diketones as the consequence of proximal ring-opening reactions. In one case the unexpected formation of benzocycloheptenedione complexes is observed. Treatment of 4 with an excess of 1-ethoxy-1-lithioethene gives the product of a dianionic oxy-Cope rearrangement followed by an intramolecular aldol addition. This is also the case with lithiated methoxyallene, and as the result the first head-to-head coupling product 12 of two methoxyallene molecules is isolated in good yield. 12 is used as a diene in Diels-Alder cycloadditions, and its molecular structure is compared to that of the similar molecule 13, lacking the two exo methylene substitutents.",
keywords = "Benzocyclobutene, Benzocycloheptenedione, Chromium, Dianionic Oxy-Cope Rearrangement, Methoxyallene",
author = "Beate Voigt and Michael Brands and Richard Goddard and Rudolf Wartchow and Holger Butensch{\"o}n",
year = "1998",
month = dec,
day = "23",
doi = "10.1002/(SICI)1099-0690(199812)1998:12<2719::AID-EJOC2719>3.0.CO;2-H",
language = "English",
pages = "2719--2727",
journal = "European Journal of Organic Chemistry",
issn = "1434-193X",
publisher = "Wiley-VCH Verlag",
number = "12",

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TY - JOUR

T1 - Addition and Ring Expansion Reactions of Tricarbonyl-(1,2-dioxobenzocyclobutene)chromium(0) with Carbon Nucleophiles

T2 - Unexpected Formation of Benzocycloheptene Derivatives and the First Head-to-Head Coupling of Two Methoxyallene Molecules

AU - Voigt, Beate

AU - Brands, Michael

AU - Goddard, Richard

AU - Wartchow, Rudolf

AU - Butenschön, Holger

PY - 1998/12/23

Y1 - 1998/12/23

N2 - Addition of carbon nucleophiles to (benzocyclobutenedione)tricarbonylchromiuni(0) (4) results in the formation of exo mono- and diadducts as well as 1,2-diketones as the consequence of proximal ring-opening reactions. In one case the unexpected formation of benzocycloheptenedione complexes is observed. Treatment of 4 with an excess of 1-ethoxy-1-lithioethene gives the product of a dianionic oxy-Cope rearrangement followed by an intramolecular aldol addition. This is also the case with lithiated methoxyallene, and as the result the first head-to-head coupling product 12 of two methoxyallene molecules is isolated in good yield. 12 is used as a diene in Diels-Alder cycloadditions, and its molecular structure is compared to that of the similar molecule 13, lacking the two exo methylene substitutents.

AB - Addition of carbon nucleophiles to (benzocyclobutenedione)tricarbonylchromiuni(0) (4) results in the formation of exo mono- and diadducts as well as 1,2-diketones as the consequence of proximal ring-opening reactions. In one case the unexpected formation of benzocycloheptenedione complexes is observed. Treatment of 4 with an excess of 1-ethoxy-1-lithioethene gives the product of a dianionic oxy-Cope rearrangement followed by an intramolecular aldol addition. This is also the case with lithiated methoxyallene, and as the result the first head-to-head coupling product 12 of two methoxyallene molecules is isolated in good yield. 12 is used as a diene in Diels-Alder cycloadditions, and its molecular structure is compared to that of the similar molecule 13, lacking the two exo methylene substitutents.

KW - Benzocyclobutene

KW - Benzocycloheptenedione

KW - Chromium

KW - Dianionic Oxy-Cope Rearrangement

KW - Methoxyallene

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U2 - 10.1002/(SICI)1099-0690(199812)1998:12<2719::AID-EJOC2719>3.0.CO;2-H

DO - 10.1002/(SICI)1099-0690(199812)1998:12<2719::AID-EJOC2719>3.0.CO;2-H

M3 - Article

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JO - European Journal of Organic Chemistry

JF - European Journal of Organic Chemistry

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