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1

Synthesis of Endothiopeptides by Using the 'Azirine/Oxazolone Method'

Bärtsch A., Bischof B., Heimgartner H.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 2

195-206

EN

The reaction of tert-butyl- or THP-pro tected mandelic thioacid (7a and 7b) with N,N,2,2-tetramethyl-2H-azirin-3-amine (2a) gave the dipeptide analogues tBu- and THP-Mns-Aiby[CS]NMe2 (8a and 8b, resp.) with a C-terminal thioamide group. Treatment of 8a with HCl gas in toluene led to 2-(1-tert-butoxy benzyl)-4,4- dimethyl-1,3-thiazole-5(4H)-one (9), which reacted with dimethylamine via ring opening to give tBu-Mnsy[CSNH]Aib-NMe2 (11a), an isomer of 8a with the thioamide group within the chain, i.e., the product of a sulfur migration. In the case of 8b, selective deprotection of the THP-hydroxy group was achieved by treatment with pyridinium p-toluenesulfonate (PPTS) in ethanol. Cyclization of the resulting Mns-Aiby[CS]NMe2 (13) yielded the 2-thioxomorpholin-5-one 10. In a similar manner, Boc-Val-SH (14) reacted with azirine 2b to give Boc-Val-Aiby[CS]N(Me)Ph (15a), which was transformed to Fmoc-Val-Aiby[CS]N(Me)Ph (15b) and further to Fmoc-Valy[CSNH]Aib-N(Me)Ph (16) by treatment with ZnCl2 in acetic acid. Coupling of two of these molecules via the 1,3-thiazol-5(4H)-one 17 yielded the endodithiopeptide Fmoc- Valy[CSNH]Aib-Valy[CSNH]Aib-N(Me)Ph (19).

2

Reaction of 1,2-Di(1-adamantyl)-2-thioxoethanone with Diazomethanes; 1,3- versus 1,5-Dipolar Electrocyclization of a Sterically Crowded Thiocarbonyl S-Methylide

Mlostoń G., Urbaniak K., Nomura T., Nakayama J., Heimgartner H.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 11

1945-1951

EN

The reaction of 1,2-di(1-adamantyl)-2-thioxoethanone (4c) with diazomethane and 2-diazopropane yielded 2-acylthiiranes 6a and 6b, respectively, and no 1,3-oxathioles of type 7 were formed. The reaction course is explained via [2+3]-cycloaddition, elimination of N2, and 1,3-dipolar electrocyclization of the in ter me di ate acyl-substituted thiocarbonyl ylides of type 1. The fail ure of the competitive 1,5-dipolar electrocyclization is a result of the sterically unfavor able conformation 1a.

3

Preparation and Structure of Optically Active Imidazolium Tetrafluoroborates; in Search of New Chiral Ionic Liquids

Mlostoń G., Mucha P., Tarka R., Urbaniak K., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 6

1105-1114

EN

Enantiomerically pure (R)-1-(1-phenylethyl)imidazoles 4a,b can be prepared conveniently from alfa-(hydroxyimino)ketones 1, (R)-1-phenylethylamine and form aldehyde, fol lowed by deoxygenation with Raney-Ni. Similarly, the reaction with (R,R)-trans-cyclohexane-1,2-diamine yields enantiomerically pure (R,R)-trans-1,1'-cyclohexane-1,2-diyl)imidazoles 4c,d. Alkylation of these imidazole derivatives with alkylbromides leads to the corresponding 3-alkylimidazolium bromides 6 and 8, respectively, which on treatment with sodium tetrafluoroborate are transformed into the correspond ing tetrafluoroborates 7 and 9. Whereas some of the imidazolium salts 7 show properties of chiral ionic liquids, the bis-imidazolium tetrafluoroborates 9 are high-melting crystalline materials.

4

Ambivalent Nucleophilicity of 1,4,5-Trisubstituted Imidazole-2-thiones in Reactions with Dimethyl Acetylenedicarboxylate and Phenylisocyanate

Mlostoń G., Gendek T., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 8

1561-1561

EN

The 1,4,5-trisubstitued 2,3-dihydro-1H-imidazole-2-thiones 1 react with electrophilic re agents via the S- or the N(3)-atom. The reaction with dimethyl acetylenedicarboxylate in methanol at room temperature occurs by the nucleophilic addition of the S-atom to give the corresponding 2-[(1H-imidazol-2-yl)sulfanyl]fumarates 4 in high yield. On the other hand, imidazole-2-thiones 1 react with phenylisocyanate in dichloromethane at room temperature to yield 2,3-dihydro-2-thioxo-1H-imidazole-1-carboxamides 5. The structures of both types of adducts were established by X-ray crystallography.

5

Synthesis of 1,3-Oxaselenan-2-imines from Isoselenocyanates

Sommen G., Heimgartner H.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1413-1418

EN

The reactions of aryl isoselenocyanates 1 with 3-chloropropan-1-ol (8) in the presence of sodium hydride in dichloromethane at room temperature gave 1,3-oxaselenan-2-imines 10 in fair yield. A reaction mechanism via nucleophilic attack of the alcoholate at the isoselenocyanate 1, followed by an 6-exo-tet cyclization, is most likely.

6

Reactions of 9H-Fluorene-9-thione with (Trimethylsilyl)diazomethane

Mlostoń G., Urbaniak K., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 11

1849-1860

EN

he [3+2]-cycloaddition of (trimethylsilyl)diazomethane (7) with 9H-fluorene-9-thione (1) at –60°C yields the spirocyclic 2,5-dihydro-5-trimethylsilyl-1,3,4-thiadiazole 10, which eliminates nitrogen at room temperature to give the 1,4-dithiane derivative 13 by dimerization of the intermediate fluorenethione (trimethylsilyl)methanide (11). This thiocarbonyl ylide can be trapped by 1 to give the 2-trimethylsilyl-1,3-dithiolane 14 via [3+2]-cycloaddition. Further more, the 1,3-di pole 11 under goes successfully [3+2]- cycloadditions with the C=S group of the phosphonyldithioformate 15 as well as with the C=C dipolarophiles maleic an hydride (18a) and N-(cyclohexyl)maleimide (18b). The structures of 13 and 14 have been established by X-ray crystallography.

7

[2+3]-Cycloadditions of Diazoalkanes with Imines of Hexafluoroacetone and Chloral

Mloston G., Bodzioch A., Cebulska Z., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

631-641

EN

The reactions of N-arylimines 1 and 2 of hexafluoroacetone and chloral, respectively, with diazoalkanes at –60C to room temperature led to the corresponding 4,5-dihydro- 1H-[1,2,3]triazoles 4 and 5, in a regioselective [2+3]-cycloaddition. The structure of one example in each case has been established by X-ray crystallography. The thermal decomposition of these adducts yielded the corresponding aziridines, bearing two trifluoromethyl and one trichloromethyl group, respectively, at C(2).

8

New Thiocarbonyl Ylides Derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and Reactions

Woźnicka M., Rutkowska M., Mlostoń G., Majchrzak A., Heimgartner H.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 10

1683-1693

9

Chemoselectivity of the [2+3]-Cycloaddition of Thiocarbonyl Ylides with 5-Benzylidene-3-phenylrhodanine

Seyfried M., Linden A., Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 8

1363-1376

EN

Reactions of three different thiocarbonyl S-methylides, generated from thiobenzophenone (2), 2,2,4,4-tetramethyl-3-thioxocyclobutanone (3), and adamantanethione (8), respectively, and diazomethane, with 5-benzylidene-3-phenylrhodanine (12) were carried out. The aromatic thiocarbonyl ylide 1a adds chemoselectively to the C,C-double bond, but the spirocyclic 1,3-dithiolane 18, i.e. the [2+3]-cycloadduct with the C=S group of 12,was also formed as a minor product. In the cases of the aliphatic thiocarbonyl ylides 6 and 20, the [2+3]-cycloaddition occurred at the exocyclic C,C-double bond exclusively to give the spirocyclic tetrahydrothiophene derivatives 23 and 21, respectively. Asmooth acid-catalyzed decomposition of 18 yielded the 2-diphenylmethylidene derivative 19. The formation of product 24, which was obtained in the reaction of the sterically congested ylide 6 with 12, is explained by a 1,4-H-shift in an intermediate zwitterionic adduct. The structures of the tetrahydrothiophenes 17, 21 and 23, as well as that of 24, were established by X-ray crystallography.

10

Synthesis and Structure of Spirocyclic Tetrahydrothiophene Derivatives Bearing a 'Cage' Residue

Romański J., Mlostoń G., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 6

973-979

EN

Trapping of the thiocarbonyl S-methanide 4 with tetracyanoethene and N-methylmaleimide led to the [3+2]-cycloadducts 11 and 12, respectively. The structures of these cycloadducts were established by X-ray crystallography. The 1,3-dipole 4 has been generated by thermal decomposition of the corresponding 2,5-dihydro-1,3,4-thiadiazole 2, which was prepared by the 1,3-dipolar cycloaddition of diazomethane with thioketone 1.

11

Addition of Diazomethane to Phosphonodithioformates and Reactions of Phosphonylated Thiocarbonyl S-Methylides

Urbaniak K., Mlostoń G., Gulea M., Masson S., Heimgartner H.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 9

1483-1494

EN

The reaction of phosphonodithioformates 14 with diazomethane at -60 graduate C yielded 2,5-dihydro-1,3,4-thiadiazoles 15 as unstable intermediates. Their structure was evidenced by the base-catalyzed elimination of methylsulfane leading to 1,3,4-thiadiazole- 2-phosphonates. At ca. -35 graduate C, thermal decomposition of 15 by N2-elimination led to reactive thiocarbonyl S-methylides 17. In the absence of trapping reagents, these 1,3-dipoles undergo a head-to-head dimerization leading to 1,4-dithianes 18. An intermediate zwitterionic dimer 19 was detected by 31P NMR spectroscopy. The initially formed thiocarbonyl S-methylide 17 as well as an open-chain zwitterionic dimer 20 was intercepted by methanol. Stable interception products were also obtained with S- and N-nucleophiles.

12

Polycyclic [2+3]-Cycloadducts from the Thermal Decomposition of Bis(2,5-dihydro-1,3,4-thiadiazoles) in the Presence of N-Methylmaleimide

Mlostoń G., Celeda M., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2004

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Vol.78 /nr 11-12

2089-2099

13

Synthessi of 3-Benzyl-1,3-thiazolidines by {2+3}-Cycloaddition of Sonochemically Generated Azomethine Ylides with Thiocarbonyl Compounds

Gebert A., Linden A., Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 7

867-879

EN

Sonification of N-benzyl-N-(methoxymethyl)-N-[(trimethylsilyl)methyl]amine (5a) in the presence of LiF led to the formation of the reactive azomethine ylide 1d, which was intercepted by cyclic thioketones to give spirocyclic 1,3-thiazolidines. In the case of 2,2,4,4-tetramethylcyclobutane-1,3-dithione (13), the 1:1- and 1:2-cycloadduct, respectively, was formed as the major product depending on the ratio of the starting materials. With 1,3-thiazole-5(4H)-thiones, 1d undergoes stereoselective [2+3]-cycloadditions with the C=S group to yield spirocyclic 1:1-adducts. In the case of the 1,3-dipole generated from N-benzyl-N-(methoxymethyl)-N-[1-(trimethylsilyl)ethyl]amine (5b), the [2+3]-cycloaddition proceeded in a non-regioselective manner leading to a mixture of regio- and diastereoisomers.

14

Synthesis of N-Unsubstituted 1,3-Thiazollidines by [2+3]-Cycloaddition of an Azomethine Ylide with Thiocarbonyl Compounds

Gebert A., Linden A., Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 2

157-167

EN

1,3-Dipolar cycloadditions of azomethine ylides with thiocarbonyl compounds have been used for the preparation of N-unsubstituted 1,3-thiazolidines. The reactive 1- phenyl-N-(trimethylsilyl)azomethine ylide (1c) was generated in situ by treatment of N-(benzylidene)[(trimethylsilyl)methyl]amine (6) with trimethylsilyl triflate and CsF in HMPA. All cycloadditions proceeded non-regioselectively, which led to mixtures of 4-phenyl- and 2-phenyl-substituted 1,3-thiazolidines.

15

Interception of an Intermediate Thiocarbonyl Ylide by NH-Compounds

Mlostoń G., Janicka E., Woźnicka M., Linden A., Heimgartner H.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 12

1805-1817

EN

By thermal decomposition of 1,1,3,3-tetramethyl-5-thia-7,8-diazaspiro[3.4]octan- 2-one (1), 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-methylide (2) was generated as an intermediate. This reactive "thiocarbonyl ylide" was trapped by protic agents such as alcohols, NH- and SH-acidic compounds to give 1,3-adducts of the acetal type. In a mixture of methanol and ammonia, the spiroheterocycle 1 was deprotonated and competitive ring opening of the 2,5-dihydro-1,3,4-thiadiazole and the cyclobutane ring occurred to give the hydrazono derivative 7 and the 1,3,4-thiadiazole 8, respectively. Surprisingly, 2 was intercepted by maleimide in a 1,3-dipolar cycloaddition.

16

Reaction of 2,2,4,4-Tetramethyl-3-thioxocyclobutanone with Dimethyl Diazomalonate Catalyzed by Rh2(OAc)4

Mlostoń G., Romański J., Heimgartner H.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 4

551-555

EN

The reaction of 2,2,4,4-tetramethyl-3-thioxocyclobutanone (1) with dimethyl diazomalonate in the presence of Rh2(OAc)4 in toluene at 50_C yielded a mixture of three products 10, 11, and 12. Thiocarbonyl ylide 8 is believed to be the common intermediate. The formation of 10 is rationalized by the 1,3-dipolar electrocyclization of 8 to give spirocyclic thiirane 9, which spontaneously eliminated sulfur. On the other hand, the 1,5- dipolar electrocyclization of 8 led to 1,3-oxathiole 11, which is converted into lactone 12 by hydrolysis.

17

Reactions of Thioesters with Organic Azides-A Novel Accesss to Imidates and Thioimidates

Mlostoń G., Romański J., Heimgartner H.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 7

975-982

EN

The reaction of O-methyl thiocarboxylates 8a, b with organic azides at 110_C yielded the corresponding imidates of type 9, which were easily hydrolyzed to give amides 10. The formation of 9 can be rationalized by a 1,3-dipolar cycloaddition of the azide with the C=S group, followed by the "twofold extrusion" ofN2 and S. The analogous reaction with methyl dithiobenzoate (11) led to thioimidates 13. On heating, the latter were transformed into thioamides 12.

18

Generation and Typical Reactions of Thiocarbonyl Ylides

Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 11

1503-1532

EN

In recent years, thiocarbonyl ylides found new application as useful building blocks in syntheses of sulfur containing heterocycles. They were also shown to play an important role as key intermediates in two-step [3+2] cycloaddition reactions. Strategies explored for the generation of thiocarbonyl ylides and their typical reactions including [3+2] cycloadditions,1,3- and 1,5-electrocyclizations, additions of OH, SH, and NH groups, and rearrangements are presented. Reactivities of isolable, push-pull stabilized thiocarbonyl ylides are compared with those proposed as transient species.

19

A novel type of ring closure of amino-substituted thiocarbonyl ylides

Romański J., Mlostoń G., Linden A., Heimgartner H.

Polish Journal of Chemistry

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1999

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vol. 73 nr 3

475-485

EN

The reaction of 4,4-dimethyl-1,3-thiazole-5(4H)-thiones 7a-c with dimethyl 2-diazo-3-(phenyloamino)butanoate (2), prepared from dimethyl fumarate and phenyl azide, in toluene at 800C yielded mixtures of dimethyl 2-(4,5-dihydro-4,4-dimethyl-1,3-thiazol-5-ylidene)-3-(N-phenylamino)butanedioates of type 11 and four diastereoisometric 4,4-dimethyl-9-phenyl-1,6-dithia-3,9-diazaspiro[4,4]non-2-ene-7,8-dicarboxylates of type 12. The formation of the products of type 12 is rationalized by a novel cyclization of intermediate thiocarbonyl ylides 9. The structures of cis-12a, cis-12c, and trans-12c were established by X-ray crystallography.

20

Trapping of thiocarbonyl ylides with NH-azoles; A novel route to N-substituted azoles

Mlostoń G., Gendek T., Heimgartner H.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 1

66-72

EN

Thermal decomposition of 2,5-dihydro-1,3,4-thiadiazoles (1) in the presence of imidazole, pyrazole, 3-phenylpyrazole, and 1,2,4-triazole, respectively, yielded S,N-acetals of type 4. Interception of initially formed thiocarbonyl ylide 2 by the NH-azole is proposed as the reaction mechanism. Treatment of the S,N-acetals 4 with Raney-Ni gave N-substituted azole 6.