Halogenvinylencarbonate in der organischen Synthese

Scharf, Hans‐Dieter

doi:10.1002/ange.19740861602

Angewandte Chemie

1974

DOI: 10.1002/ange.19740861602

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Halogenvinylencarbonate in der organischen Synthese

Hans‐Dieter Scharf¹

Abstract: Die Mono-und Dihalogenvinylencarbonate bilden eine neue Klasse von Cyclophilen, die es gestatten, maskierte a-Hydroxyketo-bzw. a-diketo funktionen durch Cycloadditionen simultan in die Addukte einzufiihren. Die Demaskierung gelingt durch einfache Hydrolyse. Die solvolytische &hung des Carbonatrings fuhrt bei den Monohalogenverbindungen zu Abkommlingen der Glykolsiure, bei den Dihalogenverbindungen zu Derivaten der Glyoxylsaure. -Die Darstellung der Titelverbindungen sowie ihre Leistungsfahigkeit als Synthesere… Show more

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Cited by 27 publications

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“…(I), 78128-66-2; (2), 78128-67-3; (3). 78128-68-4; Cr(CO)6, 13007-92-6; Mo(CO)*, 13939-06-5; W(CO)6, 14040-1 1-0; c-LiC6H4Li, 51241-56-6; [Et,OI BF,, [I] Transition metal-Carbene Complexes, Part 116.-Part 115: E. 0.…”

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Simple Synthesis of l,3‐Dialkyl‐4,5‐dihalo‐2(3H)‐imidazolones

Wamhoff

Kleimann

Kunz

et al. 1981

Angew. Chem. Int. Ed. Engl.

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slight effect on the bonding of the carbene carbon atom, but that the coordination octahedron of the metal is markedly distorted. The Ccarbene-Cr and Ccarbene--Cphenylene bond lengths are comparable with those found in other alkoxy(ary1)carbene complexes of chromium, only Ccarbene-O is slightly shorter (cf.l7]). The angles at Ccarbene are not unduly affected by the ring formation. The phenylene ring is essentially coplanar with the atoms of the two carbene groups and, within the standard deviations, shows no bond-length alternation.The coordination octahedron is distorted in two respects by the chelate effect of the biscarbene ligand (Ccarbene-Cr-Ccarbene angle of 81.3") (cf. [' I): 1. Since the trans--Ccarbene-Cr-CCO groups in the plane of the carbene ligands with 179.0 and 178.5" are almost linear and no bending of this plane takes place, the Cco-Cr-CcO angle of 82.3" is likewise very small, while the cis-Crarbene-Cr-Cco angles of 98.5 and 97.9" are distinctly widened.-2. The CO ligands perpendicular to the carbene plane are bent in towards the chelate ring and form an angle of 171.7(3)' with each other. ProcedureA suspension of Cr(C0)6 (2.5 g, 11.3 mmol) in 150 ml tetrahydrofuran is treated at 0°C with 80 ml of a 0 . 1 5~ solution of odilithiobenzene in ether and the mixture stirred for 1 h. The solvent is then removed and the residue is taken up in 100 ml of dichloromethane (-IOOC). A solution of triethyloxonium salt in CH2Cl2 is now added dropwise until the mixture no longer reacts alkaline, and, after 15 minutes' stirring, the mixture is evaporated to dryness. The crude product is chromatographed at -25°C with pentane/CH2CI2 (5 : 1) on silica gel. The eluate of the almost black zone is evaporated down, dissolved in pentane, and allowed to crystallize at -78°C; m.p. 115°C (I). (2) and (3) are obtained analogously; m.p. 104°C and 114"C, respectively.

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confidence: 99%

Simple Synthesis of l,3‐Dialkyl‐4,5‐dihalo‐2(3H)‐imidazolones

Wamhoff

Kleimann

Kunz

et al. 1981

Angew. Chem. Int. Ed. Engl.

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Ringverengungen und Ringerweiterungen vicinal disubstituierter Cyclobutane bzw. Cyclopropylmethylverbindungen

Conia

Robson

1975

Angewandte Chemie

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Einfache Synthese von 1,3‐Dialkyl‐4,5‐dihalogen‐2(3H)‐imidazolonen

Wamhoff¹,

Kleimann²,

Kunz³

et al. 1981

Angewandte Chemie

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Professor Rolf Appel zum 60. Geburtstag gewidmet Nachdem Maleinsaureanhydride und -imide[2a1 sowie Vinylencarbonate[2b1 und deren Dihal~genderivate~',~], 4-Oxazolin-2-0ne[~"~, 1,3-Dioxole und 1,4-Di0xen[~~' als cyclophile Molekule untersucht worden sind, fehlte noch eine ergiebige Synthese der potentiell cyclophilen 4,5-Dihalogen-2(3 H)-imidaz~lone'~~.Wir fanden einen einfachen Zugang zu den Titelverbindungen (4). Trichlor-(la)61 oder Tribromimidazol ( 1~)~'~ werden rnit Dialkylsulfat zu den Alkylimidazolen (2a-d) alkyliert und sodann mit Trialkyloxonium-tetrafluoroborat in hohen Ausbeuten zu den kristallinen, stabilen, hochschmelzenden Imidazoliumsalzen (3a-d) quaternisiert. Die in Dimethylformamid gut loslichen Sake (3a-d) tauschen in verdiinntem Natriumhydroxid den 2-Halogensubstituenten selektiv und nahezu quantitativ gegen die Hydroxygruppe aus. Die intermediaren 2-Hydroxyimidazoliumsalze spalten mit NaOH sogleich NaBF, ab und ergeben die 4,5-Dihalogen-2(3H)-imidazolone ( 4 -d ) (siehe Tabelle l)[*]. Wahrend die Chlorderivate (4a, b) stabil sind, zerset-

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Halogenvinylencarbonate in der organischen Synthese

Cited by 27 publications

References 73 publications

Simple Synthesis of l,3‐Dialkyl‐4,5‐dihalo‐2(3H)‐imidazolones

Simple Synthesis of l,3‐Dialkyl‐4,5‐dihalo‐2(3H)‐imidazolones

Ringverengungen und Ringerweiterungen vicinal disubstituierter Cyclobutane bzw. Cyclopropylmethylverbindungen

Einfache Synthese von 1,3‐Dialkyl‐4,5‐dihalogen‐2(3H)‐imidazolonen

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