Wyniki wyszukiwania - BazTech

1

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

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

Polish Journal of Chemistry

|

2007

|

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.

2

Synthesis of Iminosugars from alfa,beta-Unsaturated Lactones and N-Benzyl Nitrone

Panfil I., Urbańczyk-Lipkowska Z., Chmielewski M.

Polish Journal of Chemistry

|

2005

|

Vol. 79 / nr 2

239-249

EN

1,3-Dipolar cycloadditions of N-benzyl nitrone 12 to D-glycero _-lactone 13 and to D-threo _-lactone 14 proceed with excellent stereoselectivity to provide only one adduct in each case, 16 and 17, respectively. The same reaction performed with L-erythro _-lactone 15 afforded two stereoisomers 18 and 19 in the ratio ca. 2.5:1. Cycloadducts 16-19 were subsequently subjected to a sequence of reactions involving hydrogenolysis of the N-O bond and intramolecular alkylation of the nitrogen atom by C-4 or C-5 carbon atom of the sugar backbone to afford 1,2-dideoxy iminosugars 25, 31, 38, 44 and 50 with a protected hydroxymethyl group at C-2 carbon atom.

3

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

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

Polish Journal of Chemistry

|

2005

|

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.

4

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

|

2004

|

Vol.78 /nr 11-12

2089-2099

5

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

|

2003

|

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.

6

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

|

2003

|

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.

7

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

Mlostoń G., Romański J., Heimgartner H.

Polish Journal of Chemistry

|

2001

|

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.

8

Adamantanethione and diazomethane : dual regiochemistry of cycloadditions [1]

Huisgen R., Mlostoń G.

Polish Journal of Chemistry

|

1999

|

vol. 73 nr 4

635-644

EN

Cycloadditions of diazoalkanes to thiones take place in two directions furnishing 1,3,4-thiadiazolines and/or their 1,2,3-isomers, depending upon the substituents. Adamantanethione and diazomethane give rise to both regioisomers; a literature report on the high solvent dependence of the isomer ratio is confirmed, and the two regioisomers are isolated. The 1,3,4-thiadiazoline 20 eliminates N2 at 800C(t1/2 55s) in a 1,3-dipolar cycloreversion; the thiocarbonyl ylide 22 generated undergoes electrocyclization, forming a thiirane, or is intercepted by reactions with HX (thiols, alcohols) or dipolarophilic multiple bonds. The N2 extrusion from the isomeric 1,2,3-thiadiazoline 21 is at 800C 600 times slower; the formation of the spirothiirane and homoadaadamantane-2-thione is explained by a diazonium thiolate as an intermediate.