Showing papers by "Ernst Schaumann published in 1977"
TL;DR: In this article, the reaction of 1 with the sterically hindered alkyl isothiocyanates 2f is split to form the carbodiimides, which can be characterized by hydrolysis, protonation and methylation to give 6-8 cyclisieren.
Abstract: Die aktivierten Isothiocyanate 2a, b reagieren mit dem Azirin 1 unter offnung der 1,3-Bindung zu den Dipolen 5, die sich durch Hydrolyse, Protonierung und Methylierung zu 6–8 charakterisieren lassen. Im Falle der sterisch gehinderten Alkylisothiocyanate 2f–i tritt Ringoffnung von 5 zu Carbodiimiden 10 ein. 10f–i hydrolysieren uber 5 zu den Thioharnstoffen 11, die fur 11f, g leicht zu den 2-Thiohydantoinen 12 cyclisieren. Cycloadditionsreaktionen mit 10f fuhren zu den Heterocyclen 14, 15 und 17. Die Alkylisothiocyanate 2c–e bilden mit 1 je nach den Reaktionsbedingungen die 3:1-Addukte 14 oder die dipolaren 2:1-Addukte 21. Die Hydrolyse von 21e fuhrt uber das ringoffene Produkt 25 zum Thiazolinon 26.
Cycloaddition Reactions of Heterocumulenes, IX. 1:1-, 2:1-, and 3:1-Adducts from the Reaction of Isothiocyanates with 3-Dimethylamino-2,2-dimethyl-2H-azirine
Treatment of the azirine 1 with the activated isothiocyanates 2a, b leads to 1,3-cleavage of the ring and formation of the dipoles 5, which can be characterized by hydrolysis, protonation and methylation to give 6–8. In the reaction of 1 with the sterically hindered alkyl isothiocyanates 2f–i the ring of 5 is split to form the carbodiimides 10. 10f–i hydrolyze via5 to give the thioureas 11, from which 11f, g easily cyclize to yield the 2-thiohydantoins 12. Cycloaddition reactions of 10f lead to the heterocycles 14, 15, and 17. The alkyl isothiocyanates 2c–e react with 1, depending on the reaction conditions, to give the 3:1-adducts 14 or the dipolar 2:1-adducts 21. The hydrolysis of 21e leads to the thiazolinone 26 with the acyclic product 25 as intermediate.
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TL;DR: In this article, the properties of α-Alkoxyalkylphosphonates 3b with a bulky second substituent at the α-carbon atom are discussed.
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TL;DR: The crystal and molecular structures of the cycloadduct from isopropyl[α-(dimethylthio-carbamoyl)isopropymide and methyl isothiocyanate were determined by single-crystal X-ray methods as mentioned in this paper.
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TL;DR: The crystal structure of the title compound has been determined by X-ray diffraction as discussed by the authors, which is monoclinic, space group P21/c, with Z = 4 in a unit cell of dimensions: a = 7.077, b = 11.644, c= 11.955A, β = 106.74°.
Abstract: The crystal structure of the title compound has been determined by X-ray diffraction. Crystals are monoclinic, space group P21/c, with Z= 4 in a unit cell of dimensions: a= 7.077, b= 11.644, c= 11.955A, β= 106.74°. The structure was solved by direct phase-determining methods and refined to R 0.030 for 1 860 reflections. Except for the C-methyl groups all non-hydrogen atoms are in a single plane. The positive charge is centred essentially at the N(2) atom and the negative charge at the exocyclic S(2) atom. Solution i.r.measurements and temperature-dependent n.m.r. spectra gave no indication of a dipolar species, but revealed the presence of a 2-isothiocyanato-thiocarboxamide, which is formed from the original dipole by ring-opening; this reaction is reversible.
TL;DR: In this article, the Titelverbindungen (III) with sterisch anspruchsvollem zweiten Substituenten am α-Kohlenstoffatom werden durch Michaelis-Arbuzov-Reaktion der α-Chlorather (I) and den Phosphiten (II) dargestellt.
Abstract: Die Titelverbindungen (III) mit sterisch anspruchsvollem zweiten Substituenten am α-Kohlenstoffatom werden durch Michaelis-Arbuzov-Reaktion der α-Chlorather (I) und den Phosphiten (II) dargestellt.