Substituted 1,3,2,4‐benzodithiadiazines and related compounds

Despite some limitations, the 1:1 condensation of n‐RC₆H₄‐N=S=N‐SiMe₃ (n = 2, 3, 4; R = CH₃, OCH₃, F, Cl, CF₃) with SCl₂, followed by intramolecular electrophilic ortho‐cyclization, was found to be a general synthetic approach to the corresponding 5‐R, 6‐R, and 7‐R–substituted 1,3,2,4‐benzodithiadiazines, formally antiaromatic 12π‐electron compounds. For precursors with n = 3, the high regioselectivity of the cyclization resulted in exclusive (R = OCH₃, F) or predominant (R = CH₃, Cl) formation of 6‐R isomers; the ratio of the major 6‐R isomer to the minor 8‐R one was found to be 72:28 (R = CH₃) or 78:22 (R = Cl). The preferred direction of cyclization is consistent with thermodynamics of the corresponding intermediate σ‐complexes as well as factors of kinetic control for an orbital‐controlled El‐Nu reaction. According to the X‐ray diffraction data, the molecules of 5‐CF₃ (15) and 6‐F (12) derivatives are nearly planar, while the molecules of 5‐OCH₃ (7) and 6‐CH₃ (4) derivatives are bent along the S¹ … N⁴ line by ∼11° (7) or 7° (4). An attempt to adopt CsF‐induced intramolecular nucleophilic ortho‐cyclization of Ar_F‐S‐N=S=N‐SiMe₃ into polyfluorinated 1,3,2,4‐benzodithiadiazines for polyfluoropyridine derivatives resulted in formation of polyfluorinated aminopyridines. Data obtained are consistent with a previously suggested scheme of sulfur–nitrogen chain shortening during cyclization. Mild acid hydrolysis of the title compounds was shown to be a convenient synthetic route to substituted 2,2′‐diaminodiphenyl disulfides (including polyfluorinated ones) via the corresponding 2‐aminobenzenethiols. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 113–124, 1999     

Substituted pyrimidines. II. 1,3-Dimethylisocytosine and related compounds

1,3-Dimethyl-1,2-dihydro-2-imino-4(3H)pyrimidinone (1,3-dimethylisocytosine) was prepared by methylation of 2-amino-3-methyl-4(3H)pyrimidinone and was degraded in alkaline solution to a mixture of 3-methyl-2-methylamino-4(3H)pyrimidinone, 1,3-dimethyl-2,4-(1H,3H)pyrimid-indione, 2-methylamino-l-methyl-4(1H)pyrimidinone, 1-methyl-2,4-(1H,3H)pyrimidindione and 3-methyl-2,4-(1H,3H)pyrimidindione. Thiation of the title compound gave both 1,2-dihydro-1,3-dimethyl-2-thio-4(3H)pyrimidinone and 1,3-dimethyl-2,4-(1H,3H)pyrimidinedithione. The title compound is a tautomerically fixed pyrimidine and its uv spectra were compared with related compounds, notably 3-methyl-2-dimethylarnino-4(3H)pyrimidinone which is also tautomerically fixed.     

Synthesis of heterocyclic compounds related to fredericamycin A – the cyclopent[g]isoquinoline system

A synthetic route is described to compounds 9 and 10 , which resemble the cyclopent[g]isoquinoline system of the antitumor agent, Fredericamycin A. The method is based upon directed lithiation of the pyridine 6 and conjugate addition to 2-cyclopenten-1-one. Cyclization of the product 7 with base then generates the required skeleton, which can be aromatized and methylated (7 → 8 → 9).     

Hydroacridines and related compounds

3,3-Dimethyl-2-oxa-1,2,3,4-tetrahydroacridine and its N-oxide and 3,3,6,6-tetramethyl-2,7-dioxa-sym-octahydroacridine N-oxide were synthesized. On heating with acetic anhydride, the N-oxides form, respectively, acetates of 3,3-dimethyl-2-oxa-1,2,3,4-tetrahydro-4-acridinol and 3,3,6,6-tetramethyl-2,7-dioxa-sym-octahydro-4-acridinol. Hydrolysis of the acetates gives the alcohols themselves. Oxidation of 3,3,6,6-tetramethyl-2,7-dioxa-sym-octahydro-4-acridinol acetate gives the corresponding N-oxide. Oxidation of 3,3,6,6-tetramethyl-2,7-dioxa-sym-octahydro-4-acridinol with manganese dioxide gives 3,3,6,6-tetramethyl-2,7-dioxa-sym-octahydro-4-acridinone.See [9] for communication VII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1218–1221, September, 1971.     

Hydroacridines and related compounds

The N-oxides of 2,4-diphenyl-5,6,7,8-tetrahydroquinoline, 2,4-diphenylpyrindane, and 7,7-dimethyl-2,4-diphenyl-6-oxa-5,6,7,8-tetrahydroquinoline were synthesized. On heating with acetic anhydride, the N-oxides form, respectively, acetates of 2,4-diphenyl-5,6,7,8-tetrahydro-8-quinolinol, 2,4-diphenyl-7-pyrindanol, and 7,7-dimethyl-2,4-diphenyl-6-oxa-5,6,7,8-tetrahydro-8-quinolinol; hydrolysis of the acetates gives the alcohols.See [10] for communication X.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1547–1551, November, 1972.     

Hydroacridines and related compounds

4-Benzoylhydroacridines were synthesized by the reaction of 4-lithiohydroacridines with benzonitrile or benzoyl chloride. Their capacity for keto-enol tautomerism was noted.See [1] for communication IX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 7, pp. 984–986, July, 1972.     

Hydroacridines and related compounds

One hydrogen atom is replaced by lithium in the reaction of 1,2,3,4-tetrahydroacridine and sym-octahydroacridine with phenyllithium; effective replacement of a second hydrogen atom by lithium becomes possible after replacement of the first lithium by an alkyl group. This makes it possible to achieve step-wise alkylation.See [1] for communication VIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 673–675, May, 1972.     

Gibberellins and related compounds

Conclusions A study was made of the photochemical aromatization of the 2-keto derivative of gibberellic acid in various solvents. Unusual fragmentation of the B ring, with the formation of the seco-structure, was observed when the reaction was run in benzyl alcohol.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2037–2040, September, 1971.     

Benzoxazines and related compounds

The reaction of 2-mercapto(and benzylthio)-α,α-dialkylbenzyl alcohols with nitriles under the influence of acids serves as a method for the synthesis of 2,4,4-trisubstituted 4H-1,3-benzothiazines.     

Hydroacridines and related compounds

2-Phenyl-7,7-dimethyl-5H-7,8-dihydropyrano[4,3-b]pyridine and its N-oxide were synthesized. Refluxing of the latter with acetic anhydride gives 2-phenyl-7,7-dimethyl-8-hydroxy-5H-7,8-dihydropyrano[4,3-b]pyridine acetate; hydrolysis of the acetate gives the alcohol.See [1] for communication XII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 824–825, June, 1973.     

Hydroacridines and related compounds

The effect of substituents in the 9 and 10 positions on the reductive capacities of 9,10-disubstituted decahydroacridines was established in the case of the reduction of organic dyes (Methylene Blue, Indigo Carmine, and Brilliant Green).See [1] for communication XV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 969–972, July, 1977.     

Benzoxazines and related compounds

The action of a nitrating mixture on 2-substituted 4,4-diethyl-4H-1,3-benzoxazines gives the corresponding 6-nitro derivatives, which can be isolated as such or as the hydrolysis products –N-acyl-,-diethyl-2-hydroxy-5-nitrobenzylamines. The latter cyclize to the corresponding 4H-1,3-benzoxazines under the influence of perchloric acid.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 303–305, March, 1972.     

Benzoxazines and related compounds

A simple method has been elaborated for synthesizing 2-substituted 4,4-dialkyl-4H-1, 3-benzoxazines by the interaction between nitriles and o-oxyphenyldialkylcarbinols under the influence of acids.For part I, [1].