Reactions of tetrafluoroethylene oligomers. Part 1. Some pyrolytic reactions of the pentamer and hexaher and of the fluorine adducts of the tetramer and pentamer

Pyrolyses of these highly branched fluorocarbons over glass beads caused the preferential thermolyses of CC bonds where there is maximum carbon substitution. Fluorinations of perfluoro-3,4-dimethylhex-3-ene (tetramer) (I) and perfluoro-4-ethyl-3,4-dimethylhex- 2-ehe (pentamer) (II) over cobalt (III) fluoride at 230° and 145° respectively afforded the corresponding saturated fluorocarbons (III) and (IV), though II gave principally the saturated tetramer (III) at 250°. Pyrolysis of III alone at 500—520° gave perfluoro-2-methylbutane (V), whilst pyrolysis of III in the presence of bromine or toluene afforded 2-bromononafluorobutane (VI) and 2H-nonafluorobutane (VII) respectively. Pyrolysis of perfluoro-3-ethyl-3, 4-dimethylhexane (IV) alone gave a mixture of perfluoro-2-methylbutane (V), perfluoro-2-methylbut-1-ene (VIII), perfluoro-3-methylpentane (IX), perfluoro-3,3-dimethylpentane (X), and perfluoro-3,4- dimethylhexane (III). Pyrolysis of IV in the presence of bromine gave (VI) and 3-bromo-3-trifluoromethyl-decafluoropentane (XI): with toluene, pyrolysis gare VlI and 3H-3-trifluoromethyldecafluoropentane (XII). Pyrolysis of II at 500° over glass gave perfluoro-1,2,3-trimethylcyclobutene (XIII) and perfluoro-2,3-dimethylpenta-1,3(E)- and (Z)-diene (XIV) and (XV) respectively. The diene mixture (XIV and XV) was fluorinated with CoF₃ to give perfluoro-2,3-dimethylpentane (XVI) and was cyclised thermally to give the cyclobutene (XIII). Pyrolysis of perfluoro-2- (1′-ethyl-1′-methylpropyl)-3-methylpent-1-ene (XVII) (TFE hexamer major isomer) at 500° gave perfluoro-1-methyl-2-(1′-methylpropyl)cyclobut-1-ene (XVIII) and perfluoro-2-methyl-2-(1′-methylpropyl)buta-1,3-diene (XIX). Fluorination of XVIII over CoF₃ gave perfluoro-1-methyl-2- (1′-methylpropyl)cyclobutane (XX), which on co-pyrolysis with bromine gave VI. XIX on heating gave XVIII. Reaction of XVIII with ammonia in ether gave a mixture of E and Z 1′-trifluoromethyl-2-(1′-trifluoromethyl- pentafluoropropyliden-1′-yl)tetrafluorocyclobutylamine (XXI) which on diazotisation and hydrolysis afforded 2-(2′trifluoromethyl- tetrafluorocyclobut-1-en-1′-yl)-octafluorobutan-2-ol (XXII).     

Synthese der isomeren 3, 4-Dimethyl-4-phenyl-3, 4-dihydro-carbostyrile

Cyclisation of 2-methyl-3-phenyl-but-3-en-anilide (III) with polyphosphoric acid gave cis-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (VII) in 61% yield together with a small amount of 2, 3-dimethylindenone (VIII), whereas with AlCl₃ a phenyl group was split off to give 3, 4-dimethylcarbostyril (VI). The anilide III isomerises to cis- and trans-2, 3-dimethyl-cinnam-anilide (IV resp. V) under basic conditions. The anilides IV and V gave only small yields of the dihydrocarbostyril VII with polyphosphoric acid. Chlorination of VII in position 3 using PCl₅ yielded IX which, on splitting out HCl, gave 3-methylene-4-methyl-4-phenyl-3, 4-dihydro-carbostyril (X). X was converted to trans-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (XI) by catalytic hydrogenation.     

Synthesis of heterocycles. Part II. New routes to acetylthiadiazolines and alkylazothiazoles

Methylglyoxalyl chloride arylhydrazones (III) react with an ethanolic solution of thiourea to give 2-amino-4-methyl-5-arylazothiazoles (XII) instead of the expected 2-acetyl-4-aryl-5-imino-Δ²-1,3,4-thiadiazolines (V) which were obtained from III and potassium thiocyanate. 3-Thiocyanato-2,4-pentanedione (IV) coupled with diazotized anilines to give V. The postulated routes to formation of V and XII from III are given. Nitrosation of V gave the corresponding N-nitroso derivatives (VI) which decomposed upon refluxing in dry xylene to give 2,4-disubstituted-Δ²-1,3,4-thiadiazolin-5-ones (VII). Boiling of either V or VI with hydrochloric acid gave the hydrochloride salt (VIII). The thiadiazolines V gave the respective N-acyl derivatives (IX) and (X) with acetic anhydride and benzoyl chloride in pyridine.     

Synthesis of certain metabolites and analogs of vitamin B6 and their ring-chain tautomerism

Pyridoxol and pyridoxal on benzylation with dimethylphenylbenzylammonium hydroxide (“leucotrope”) gave 3-O-benzylpyridoxol (IV) and 3-O-benzylpyridoxal (V), respectively. As a possible mechanism of this reaction an ion pair intermediate has been postulated. Oxidation of IV and V with chromic oxide-pyridine-acetic acid complex gave 3-O-benzyl-4-pyridoxic acid lactone (VI), which could also be obtained by benzylation of 4-pyridoxic acid. Treatment of VI with dimethylamine gave 2-methyl-3-benzyloxy-5-hydroxymethylpyridine-4-N,N-dimethylcarbox-amide (X) which oxidized to form the 5-formyl derivative (XI). The latter on hydrolysis yielded the metabolite, 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylic acid (I). When reacted with liquid ammonia, VI gave 3-O-benzyl-4-pyridoxamide (VII) which was then oxidized to give 2-methyl-3-benzyloxypyridine-4,5-dicarboxylic acid cyclicimide(IX). Acid hydrolysis of IX gave another metabolite, 2-methyl-3-hydroxypyridine-4,5-dicarboxylic acid (XIII), which could also be obtained by oxidizing XI with potassium permanganate in water to yield 2-methyl-3-benzyloxy-5-carboxypyridine-4-N,N-dimethylcarboxamide (XII) and subsequent hydrolysis with hydrochloric acid. A positional isomer of I, 2-methyl-3-hydroxy-4-formylpyridine-5-carboxylic acid (XVII) was synthesized starting from 3-O-benzyl-5-pyridoxic acid lactone (XIV) following similar reaction sequences used for the preparation of I. Ring-chain tautomerism has been studied in I, XVII, opianic acid (XVIII), phthalaldehydic acid (XIX) and (2-carboxy-4,5-dimethoxy)-phenylacetaldehyde (XX) in different solvents by nmr and in the solid state by ir spectroscopy. A direct and reliable differentiation between the open form (aldehyde proton in low field) and the ring form (lactol proton in the intermediate field) has been obtained by nmr spectroscopy. In sodium deuteroxide and pyridine-d₅ the open chain form existed exclusively (except for homolog (XX) which is in cyclic form in pyridine-d₅), whereas in 18% hydrogen chloride in deuterium oxide all the compounds are completely in the cyclic form. In hexafluoroacetone hydrate-d₂, XVIII, XIX, and XX exist in the cyclic form whereas I is in the open form. In DMS0-d₆ both cyclic and open-chain forms have been observed in XVIII, XIX and XX. Definite peak assignment for the two forms could not be made in I due to broadening or superimposition with C₆-H. The metabolite I, isometabolite (XVII) and opianic acid (XVIII) form cyclic acetyl derivatives which give a sharp lactol peak. In the solid state XVIII, XIX are in the cyclic form and I and XX in the open-chain form as observed by ir spectroscopy.     

Synthesis of 5(and 6)-nitro-4-methyl-2,3-dihydro-1h-1,5-benzo-2-diazepinones

The reaction of 4-nitro-o-phenylenediamine (I) with acetoacetic ester at room temperature under acid catalysis gives ethyl 3-(2-amino-5-nitrophenylamino)crotonate (II), which is readily cyclized to 7-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (III) on heating with alkaline agents. The reaction of I with acetoacetic ester in refluxing xylene gives isomeric 8-nitro-4-methyl-2,5-dihydro-1H-1,5-benzo-2-diazepinone (IVa) or 8-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (IVb), which are readily interconverted. The synthesis of IV is complicated by the side formation of 5-nitro-2-methylbenzimidazole (V) and thermal rearrangement of IVa and IVb to 5-nitro-1-isopropenylbenzimidazolone (VI). 6-Nitro-1-isopropenylbenzimidazolone (VII) is similarly obtained on heating III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 696–699, May, 1972.     

Insect pheromones and their analogues. XVIII. Regiospecific synthesis of (±)-15,19-dimethyltritriacontane — A component of the pheromone of Stomoxys calcitrans

(±)-15,19-Dimethyltritriacontane (II) — a component of the pheromone of the stable fly — has been obtained by a five-stage synthesis from dimethylcyclooctadiene (I). The coupling of 1,1-dimethoxy-4-methyl-8-oxonon-4Z-ene [the product of the ozonolysis of (I)] with n-C₁₃H₂₇CH=PPh₃ (THF; ?30°, 2 h; 25°, 15 h; Ar) gave 1,1-dimethoxy-4,8-dimethyldocosa-4Z,8Z(E)-diene (III). The hydrolysis of (III) (TsOH·Py, H₂O-Ac, boiling, 4 h) gave the corresponding aldehyde (IV). The condensation of (IV) with n-C₁₀H₂₁CH=PPh₃ (THF; ?60° to ?30°C, 2 h, 25°C, 15 h) led to 15,19-dimethyltritriaconta-11Z(E),15Z,19Z(E)-triene (V), the exhaustive hydrogenation of which (ethanol, H₂, 5% Pd/C, 25°C) gave (II). The substance, the yield in %, and R_f values are given, respectively: (II), 95, 0.92; (III), 29, 0.74; (IV), 80, 0.72; (V) 50, 0.8. The IR and PMR spectra of compounds (II)–(V) and the mass spectra of (II) and (III) are given.     

Metallacycloalkanes : II. Reactions of α,α′-bipyridyl-5-nickela-3,3,7,7-tetramethyl-trans-tricyclo[4.1.0.02,4]heptane

The title compound (II) underwent reductive elimination on treatment with maleic anhydride, tetracyanoethylene or triphenylphosphite to give 3,3,6,6,-tetramethyl-trans-tricyclo[3.1.0.0^2,4]hexane (III). With triphenylphosphite bi(2,2-dimethylcyclopropyl) (V) and 1-(2,2-dimethylcyclopropyl)-3-methyl-1,3-butadiene (VI) were also formed. Acidolysis of II with either HCl, malonic acid or methanol gave V. An intermediate complex α,α′-bipyridyl(phenoxy)-3-nickel-1,1′-bi-(2,2′-dimethylcyclopropyl) (VIII) was isolated by reaction of II with phenol. Methylene dibromide reacts with II to give III and 3,3,7,7-tetramethyl-trans-tricyclo[4.1.0.0^2,4]heptane (IV). With triethylaluminum and II complete exchange of the alkyl groups occurred and V was released on hydrolysis. Trifluoroborane diethyl ether and II gave 3,3,6,6-tetramethylcyclohexa-1,4-diene in a rearrangement-displacement reaction. The cyclodimerisation of 3,3-dimethylcyclopropene (I) to III catalysed by II and the fact that II can be recovered from the reaction mixture provides strong evidence for the intermediacy of metallacyclopentanes in these transition-metal-catalysed [2π + 2π] cyclo-additions.     

Insect pheromones and their analogs

A four-stage asymmetric synthesis of (+)-disparlure [(7R,8S)-(+)-cis-methyl-7,8-epoxyoctadecane (V)] has been effected from 8-methylnon-2Z-en-l-ol (I), obtained by the carboalumination of acetylene with tris(5-methylhexyl)aluminum using the Sharpless reaction. The asymmetric epoxidation of (I), (Ar, mol. sieve A, (+)-DET, (iOPr)₄Ti, t-BuOOH, ?15°C, 20 h; H₂O, 1 h, NaOH, ?7°C, 30 min) gave 8-methyl-2S,3R-epoxynonan-l-ol (II), which was oxidized (kieselguhr-CrO₃-Py, 0°C, 2 h; 25°C, 2 h) to 8-methyl-2S,3R-epoxynonan-l-al (III). The coupling of (III) with n-C₈H₁₇CH=PPh₃ (?78°C, 1 h; 25°C, 15 h) gave 2-methyl-7R,8S-epoxyoctadec-9Z-ene (IV), the hydrogenation (H₂/5% Pd-C, 25°C, 5 days) of which led to (V) in admixture with an isomerization product. Compound (V) was isolated by HPLC. Substance, yield, [α] _D ²⁵ : (II), 73, ?2.75°; (III), 80, [80.8°; (IV), 50, +37.25°; (V), 50, +0.8°. The IR and PMR spectra of (II–IV), the¹³C NMR spectra of (II) and (III), and the mass spectrum of (IV) are given.     

Reaction of 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene with hydrazines

2-Methyl-3-ethoxycarbonyl-4-(N,N-dimethylhydrazino)thiophene (II) and 2-methyl-3-ethoxy-carbonyl-4-(N-phenylhydrazino)thiophene (III) are formed by the action of substituted hydrazines — N,N-dimethylhydrazine and phenylhydrazine — on 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene (I). At the same time, the thiophene ring of hydroxythiophene I undergoes hydrazinolysis under the influence of hydrazine hydrate to form 3-mercaptomethyl-4-ethoxycarbonyl-5-methylpyrazole (IV). Structure IV was proved by IR, UV, and PMR spectroscopy and by hydrogenolysis of IV to the known 3,5-dimethyl-4-ethoxycarbonylpyrazole (V).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 759–761, June, 1971.     

Synthesis of azepinoquinazoloncs from 2-methyl-3-(o-tolyl)-4-quinazolone

Some new azepinoquinazolones were synthesized from 2-methyl-3(o-tolyl)-4(3H)quinazolone (metliaqualone )as potential hypnotic agents. Methaqualone (I) reacted with dimethyl acetylene-dicarboxylate (dmad) to give the azepinoquinazolone (II) which on treatment with PPA gave the pentacyclic ketone (V). Subsequent sodium borohydride reduction of the ketone (V) gave the fused azepine (VIa). Reaction of the azepinoquinazolone (II) with formic acid resulted in cleavage of the quinazolone nucleus to give the azepine (VIII). None of the compounds synthesized exhibited significant hypnotic activity.     

2-Amino-2-thiazoline. V. phenylthioureido and phenylureido derivatives of 2-thiazoline

The reaction of 2-amino-2-thiazoline (I) with phenylisothiocyanate has been reported to give 2-imino-3-phenylthiocarbamoylthiazolidine (II) at low temperatures and l-phenyl-3-(2-thiazolin-2-yl)-2-thiourea (III) at ca. 100°. When performed by us, however, this reaction gave only a single mono-adduct regardless of the temperature. Nmr and chemical evidence indicates that structure III is the correct one. Treatment of I with phenylisocyanate also gave a mono-adduct which was established to be l-phenyl-3-(2-thiazolin-2-yl)urea (V). Compound I does not form a simple di-adduct with excess phenylisothiocyanate but does so with phenylisocyanate to give 2-phenylcarbamoylimino-3-phenylcarbamoylthiazolidine (VI). The reaction of III with phenylisocyanate gives 2-phenylthiocarbamoylimino-3-phenylcarbamoylthiazolidine (VII), however, the corresponding reaction of V with phenylisothiocyanate does not give the anticipated product but a mixture of compounds which includes VI and VII.     

Studies on the syntheses of analgesics. Part XXXII. An alternative synthesis of 1,2,3,4,5,6-Hexahydro-8-hydroxy-6,11-dimethyl-3-(3-methyl-2-butenyl)-2,6-methano-3-benzazoeine [Studies on the syntheses of heterocyclic compounds. Part CDLXXX]

Bischler-Napieralski reaction of the amides (VIII and IX), derived from the 3-methyl-3-pentenylamine (III) with the phenylacetic acid derivatives (V ～ VII), gave the 5,6-dihydropyridines (XII and XIII), which were reduced, followed by N-benzylation, to afford the 1,2,5,6-tetrahydropyridines (XIX ～ XXI). Grewe-type cyclization of these compounds gave 3-benzyl-3-benzazocine (II), which was already converted into pentazocine (Ic). Moreover, the 1,2,5,6-tetrahydropyridines (XIX ～ XXI) were also obtained from the 2-benzylidene-1,2,5,6-tetrahydropyridine (XVII ～ XVIII) from the N-benzylamine (IV) of III via the amides (X and XI).     

Insect pheromones and their analogs

A four-stage asymmetric synthesis of (+)-disparlure [(7R,8S)-(+)-cis-methyl-7,8-epoxyoctadecane (V)] has been effected from 8-methylnon-2Z-en-l-ol (I), obtained by the carboalumination of acetylene with tris(5-methylhexyl)aluminum using the Sharpless reaction. The asymmetric epoxidation of (I), (Ar, mol. sieve A, (+)-DET, (iOPr)₄Ti, t-BuOOH, –15°C, 20 h; H₂O, 1 h, NaOH, –7°C, 30 min) gave 8-methyl-2S,3R-epoxynonan-l-ol (II), which was oxidized (kieselguhr-CrO₃-Py, 0°C, 2 h; 25°C, 2 h) to 8-methyl-2S,3R-epoxynonan-l-al (III). The coupling of (III) with n-C₈H₁₇CH=PPh₃ (–78°C, 1 h; 25°C, 15 h) gave 2-methyl-7R,8S-epoxyoctadec-9Z-ene (IV), the hydrogenation (H₂/5% Pd-C, 25°C, 5 days) of which led to (V) in admixture with an isomerization product. Compound (V) was isolated by HPLC. Substance, yield, [] _D ²⁵ : (II), 73, –2.75°; (III), 80, [80.8°; (IV), 50, +37.25°; (V), 50, +0.8°. The IR and PMR spectra of (II–IV), the¹³C NMR spectra of (II) and (III), and the mass spectrum of (IV) are given.Institute of Chemistry, Bashkir Scientific Center, Urals Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 715–718, September–October, 1989.     

Dehydration of ethylenic alcohols

Summary A systematic study was made of the catalytic dehydration of 4-methyl-1-penten-3-ol (Ia), 3,4-dimethyl-1--penten-3-ol (Ib), 3-isopropyl-4-methyl-1-penten-3-ol (Ic), 2-methyl-4-penten-2-ol (II), 2-methyl-3-penten-2-ol (III), 4-methyl-3-penten-2-ol (IV), and 2-methyl-4-hexen-3-ol (V). In the course of this study methods were developed for the preparation of the following substituted gem-dimethylbutadienes: 4-methyl-1,3-pentadiene (VIII), 3,4-dimethyl-1,3-pentadiene (IX), 2-methyl-2,4-hexadiene (XI), and 3-isopropyl-4-methyl-1,3-pentadiene (XIV).     

Nucleosides. CXXXV. Synthesis of some 9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-9H-purines and their biological activities

Seven purine nucleosides containing the 2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl moiety were synthesized and tested for their antitumor activity. Direct condensation of 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide (1) with N6-benzoyladenine in CH2Cl2 followed by saponification of the product afforded the adenine nucleoside (I, 2'-F-ara-A). Deamination of I with NaNO2 in HOAc gave the hypoxanthine analogue (II, 2'-F-ara-H). The 6-thiopurine nucleoside (III, 2'-F-ara-6MP) was prepared by condensation of 1 with 6-chloropurine by the mercury procedure followed by thiourea treatment and saponification of the product. Methylation of III gave the 6-SCH3 analogue (IV). Raney Ni desulfurization of III afforded the unsubstituted purine nucleoside (V, 2'-F-ara-P). Condensation of 1 with 2-acetamido-6-chloropurine by the silyl procedure afforded the protected 2-acetamido-6-chloropurine nucleoside which served as the precursor for both the guanine and 6-thioguanine nucleosides (VI, 2'-F-ara-G and VII, 2'-F-ara-TG, respectively). Thus, alkaline hydrolysis of the precursor gave VI. Thiourea treatment prior to alkaline hydrolysis gave VII. The new nucleoside, 2'-F-ara-G (VI) is found to be selectively toxic to human T-cell leukemia CCRF-CEM.     

The synthesis and properties of certain N-methylated 5-diazouracils

The reduction of 1-methyl-, 3-methyl- and 1,3-dimethyl-5-nitrouracil (Ia-c) to the corresponding 5-aminouracils (IIa-c) is described. Diazotization of 5-amino-1-methyluracil (IIa) and 5-amino-1,3-dimethyluracil (IIc) gave 5-diazouracils which were characterized as thermally stable C6 covalent hydrates (III and XIII). Diazotization of 5-amino-3-methyluracil (IIb) gave anhydro 5-diazo-3-methyluracil (X) which underwent covalent methanolation and thermally reversible covalent hydration. Treatment of III and XIII with hot methanol resulted in solvent exchange of the C6 hydroxyl groups by a mechanism which may involve initial formation of diazoethers. Treatment of the methanolates (IV, XI and XIV) with dimethylamine resulted in coupling at the diazo group with a concomitant expulsion of the C6 methoxyl groups to give 5-(3,3-dimethyl-1-triazeno)uracils (XVa-c).     

Alkenylation by 5-hexen-2-one oxime: Prototropic isomerization under trofimov reaction conditions

From 5-hexene-2-one oxime (I) and acetylene in KOH/DMSO, 2-methyl-3-(2-propenyl)pyrrole (II), E- and Z-2-methyl-3-(1-propenyl)pyrroles (III), and E- and Z-1-vinyl-2-methyl-3-(1-propenyl)pyrroles (V) were synthesized. The isomerization of the alkenyl radical of pyrroles II was studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 477–480, April, 1992.     

Chemistry of fluorinated quinones I. The Diels-Alder reactions of fluoranil

The Diels-Alder reaction of fluoranil with cyclopentadiene, 1,3-butadiene, and 1-acetoxy-1,3-butadiene gave 1,4, 5, 8-bis(methylene)-4a, 8a, 9a, 10a-tetrafluoro-1, 4, 4a, 5, 8, 8a, 9a, 10a-octahydroanthraquinone (I), 2, 3, 4a, 8a-tetrafluoro-4a, 5, 8, 8a-tetrahydro-1,4-naphthoquinone (III), and 5-acetoxy-2, 3, 4a, 8a-tetrafluoro-4a, 5, 8, 8a-tetrahydro-1,4- naphthoquinone (VI), respectively. Hydrogenation of I gave the expected saturated diketone(II). Hydrogenation of III afforded, with elimination of the two tertiary fluorines, 2,3-difluoro-5, 6, 7, 8-tetrahydro-1, 4- dihydroxynaphthalene (IV). In hydrogenation of VI, acetic acid and two moles of hydrogen fluoride were eliminated to give 2,3-difluoro-1, 4-dihydroxynaphthalene(VII). Both dihydroxy compounds IV and VII yielded on oxidation with ferric chloride the corresponding quinones, 2, 3- difluoro-5, 6, 7, 8-tetrahydro-1, 4-naphthoquinone (V) and 2, 3-difluoro-1, 4-naphthoquinone (VIII), respectively. Equivalent amounts of compounds IV and V gave a red-brown semiquinone IX, and a mixture of VI and VIII gave a dark-violet semiquinone X.     

An investigation of the synthesis of 3-amino-4-ethoxycarbonylaminotetrahydrothiophene

Methods of synthesis of 3-amino-4-ethoxycarbonylaminotetrahydrothiophene (VIII), and of other diamines, from 4-ethoxycarbonylaminotetrahydro-3-hydroxyiminothiophene (I), 2-benzylidene-4-ethoxycarbonylaminotetrahydro-3-hydroxyiminothiophene (III) and 4-ethoxycarbonylaminotetrahydro-3-hydroxythiophene (V) were investigated. Chlorination of V followed by the Gabriel synthesis gave VIII.