Hans Suschitzky

2H-benzimidazoles (isobenzimidazoles). Part 10. Synthesis of polysubstituted o-phenylenediamines and their conversion into heterocycles, particularly 2-substituted benzimidazoles with known or potential anthelminthic activity

Abstract Polysubstiluted o -phenylenediamines were syathesised in moderate to high yield by reductive cleavage of the corresponding 2 H -benzimidazole-2-spirocyclohexane with sodium dithionite in aqueous ethanol and converted into methyl benzimidazole-2-carbamates and 2-methylthio-and 2-trifluoromethylbenzimidazoles with known or potential anthelminthic activity. 5-(Pyrimidin-2-ylthio)-benzimidazole and 1 l-(pyridin-2-ylthio)dioenzo[ a,c ]phenazine were synthesised too. Attempts to oxidise 1,3-dihydro-2 H -4,9-diazanaphth[2,3- d ]imidazole, prepared by condensation of 2,3-diaminoquinoxaline with cyclohexanone, to an analogue of the title system failed.

Synthesis of 2-substituted chromones, chromanones, and their thio analogues using organocopper reagents

Improved use of organocopper reagents provides a general route to unsymmetrical 2,2-dialkylchomanones and thiochromanones from chromones and thiochromones via a simple addition - oxidation - addition sequence

Syntheses of heterocyclic compounds. Part XXIX. Substituted 2,3-dihydro-1H-1,5-benzodiazepines

1,5-Benzodiazepine-2-spirocycloalkanes [as (6)] are made in a one-step condensation from o-phenylenediamine and cyclic ketones in cold ethanol in the presence of boron trifluoride–ether complex. The method is also applicable to acyclic ketones. The diazepines can also be prepared from the monohydrochloride of the base with a liquid ketone. Acylation, hydrolysis, reduction, and oxidation of some of these novel diazepines have been studied.

Studies in the xanthone series—III: Preparation and reactions of 1-acetyl-2-hydroxyxanthone☆

Abstract The orientation and reactions of 1-acetyl-2-hydroxyxanthone (I; R 1  Ac, R 2  R 3  H) leading to the synthesis of angular furanoxanthones (III; R  Me) and (IV) and pyronoxanthones of the type (V) are described. The ultra-violet spectra of these extended xanthone systems are discussed.

Reductive cyclization of aromatic nitro compounds to benzimidazoles with titanous chloride

Abstract N-2-Nitrophenyl-, -naphthyl-, -pyridyl-, and -quinolyl- heterocycles have been reductively cyclized to the corresponding benzimidazoles of type II and X–XVI in excellent yield with TiCl3. A reaction mechanism for this convenient synthesis is postulated.

Synthesis of heterocyclic compounds. Part 34. Reactions of chlorosulphonyl isocyanate with carbon–nitrogen double bonds

Anils react with chlorosulphonyl isocyanate (CSI) to yield triazinediones, whereas azines produce triazolotriazolones. Other compounds containing carbon–nitrogen double bonds (oximes, hydrazones, amidines, and carbodi-imides) also react with CSI giving synthetically useful results. The cycloaddition of CSI to azides is described.

Competitive cyclisations of singlet and triplet nitrenes. Part I. Cyclisation of 1-(2-nitrenophenyl)pyrazoles

Aus den 1-(2-Nitrophenyl)-imidazolen (I) erhalt man mit Triathylphosphit (II) die Cyclisierungsprodukte (III).

2H-benzimidazoles (isobenzimidazoles). Part 9. Synthesis and reactions of 4,6-dibromo-2H-benzimidazole-2-spirocyclohexane

Abstract The title compound 1 was prepared by condensation of 3,5-dibromo- o -phenylenediamine 10 with cyclohexanone and oxidation of the resulting 4,6-dibromo-1,3-dihydro-2 H -benzimidazole-2-spirocyclohexane 5 with manganese dioxide. With sodium 2,3-dichlorophenoxide, sodium benzenesulfinate, or piperidine it reacts by loss of bromine, to give the 6-substituted derivatives 2 , 3 , and 4 , respectively. Morpholine, however, gives 5,7-dibromo-4-morpholino-2 H -benzimidazole-2-spirocyclohexane 15 whilst pyrid-2(1 H )-thione and pyrimidin-2(1 H )-thione give 4-bromo-1,3-dihydro-6-(pyridin-2-ylthio)-2 H -benzimidazole-2-spirocyclohexane 6 and 5,7-dibromo-1,3-dihydro-4-(pyrimidin-2-ylthio)-2 H -benzimidazole-2-spirocyclohexane 14 , respectively. In the presence of 1 or 2 mol equiv. of sodium methoxide an aryne mechanism appears to operate, leading to the formation of either a mixture of 5-bromo-6-methoxy- 11 and 6-bromo-4-methoxy-2 H -benzimidazole-2-spirocyclohexane 12 or 5,6-dimethoxy-2 H -benzimidazole-2-spirocyclohexane 13 , respectively. Oxidation of the title compound 1 with m -chloroperoxybenzoic acid yields the 1-oxide 7 exclusively, which reacts with piperidine and morpholine by loss of the 4-bromine atom, to give compounds 16 and 17 , respectively, in the latter case with concomitant loss of oxygen.

Transformation of 3-formylchromones into pyridines and pyrroles

Abstract Interaction of 3-formylchromones with ethyl aminoethanoate provides a novel route to pyridines and pyrroles.

A new synthesis of isocyanates

The isocyanates (3)–(7) were prepared from the corresponding amine, carbonyl sulphide, and S-ethyl chlorothioformate by a procedure analogous to the Andreasch–Kaluza synthesis of isothiocyanates.