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Otto Meth-Cohn

Publications and source records attributed to Otto Meth-Cohn.

7 recordsLinked to original sources
PubMed2005

Interaction of aryloxychlorocarbenes with acetylenedicarboxylate: novel formation of polyfunctional butadienes and 8-oxatricyclo[3.2.1.0(2.4)]oct-6-enes.

The interaction of aryloxychlorocarbenes with dialkyl acetylenedicarboxylates has been examined. Thermolyses of 3-aryloxy-3-chlorodiazirines in the presence of acetylenedicarboxylate resulted in the formation of unexpected polyfunctional 1,3-butadienes and 8-oxatricyclo[3.2.1.0(2.4)]oct-6-enes or of 2-aryoxycarbonylmaleates dependent upon reaction conditions. This work confirmed the nucleophilicity of aryloxychlorocarbenes and underlined their synthetic potential.

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PubMed2003

The surprising nucleophilic addition of aminochlorocarbenes to diethyl acetylenedicarboxylate and to oxalyl chloride: quinolines and benzo[1,4]diazepines from N-alkylformanilides and oxalyl chloride in the presence of Hünig's base.

Vilsmeier reagents derived from N-methylformanilides undergo ready deprotonation with Hünig's base. In xylene, the derived nucleophilic arylaminochlorocarbenes bearing 4-methyl- and 4-methoxy-substituents react with acetylenedicarboxylates to give 2-(2-chloro-1,2-bis(ethoxycarbonyl)vinyl)-3,4-bis(ethoxycarbonyl)-1-methyl-1,2-dihydroquinolines while most derivatives react with oxalyl chloride to give substituted 1-methyl-4 phenylbenzo[f][1,4]diazepine-2,3-dicarboxylic anhydrides.

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PubMed2003

DOTTADs--readily made novel metal ligands with multivariant functionality--trans-DOTTADs and semi-DOTTADs.

Two new ligand systems related to the previously described DOTTADs have been generated in a simple one step reaction. The first, trans-DOTTADs, were formed by Vilsmeier formylation (followed by cyclisation and N-demethylation) of 2,6-dimethyl-3,5-pyrazine-dicarboxylic acid, to give the novel bis-pyridinopyrazine dialdehyde ligands. The corresponding pyrazine diester, reacted similarly to an intermediate iminium ion stage, which gave trans-DOTTAD imines on work-up with amines. The treatment of Hantzsch ester with two equivalents of benzaldehyde gave 7-phenyl-2-(2-phenylethenyl)-7,8-dihydropyrano[4,3-b]pyridin-5-one-3-carboxylic acid. This product underwent similar cyclisation with Vilsmeier reagents to give, for example, 6-methyl-2-(2-phenylethenyl)-8-(phenylhydroxymethyl)-6H-[1,6]naphthyridin-5-one-3-carboxylic acid, an example of a semi-DOTTAD.

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PubMed2003

DOTTADs--readily made novel metal ligands with multivariant functionality.

The interaction of Hantzsch pyridinecarboxylic acids with dialkylformamides and POCl3, followed by treatment with NH4OH yields 1,8-dioxo-1,2,7,8-tetrahydro-2,7,10-triazaanthracenes (DOTTADs), which have great potential as useful ligands for Group I and II metals and some transition metals. The corresponding Hantszch esters similarly for DOTTADs or their bis-imines by way of isolable intermediates, which are then treated with an amine RNH2. DOTTAD-imines are also available from DOTTADs with amines and this reaction is also effective with 1,8-diamino-3,6-dioxaoctane to give macrocyclic analogues, as well as with chiral amines. DOTTAD-imines can be reduced with diethylsilane and Wilkinson's catalyst to the corresponding amines, which can also be formed from DOTTADs by reductive amination with amines and Na(AcO)3BH. Mono-aldols of DOTTADs are easily formed by treatment of DOTTADs with acetone.

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PubMed2003

The unique nucleophilic reactivity of arylaminochlorocarbenes.

4-Methyl and 4-methoxyphenylaminochlorocarbene (readily formed by deprotonation of the Vilsmeier reagent derived from the corresponding N-methylformanilide with Hünig's base) reacted with diethyl acetylenedicarboxylate to give 1:2 quinoline adducts, while p-halophenylaminochlorocarbenes yielded benzoazepine derivatives from 2:1 interaction of the carbene with oxalyl chloride under the same reaction conditions.

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PubMed2002

Direct conversion of macrocyclic furans into macrocyclic isothiazoles.

The first calixhetarenes with more than one heteroatom in the constituent rings are prepared in one step by treatment of calix[4]furan 1a and calix[6]furan 1b with ethyl carbamate, thionyl chloride and pyridine to give 2, 3, 4 and 5, 6, 7 respectively; these products have been characterised by X-ray crystallography which reveals that in 2 all eight heteroatoms lie on one face of the macrocyle.

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