1,2‐Diaza‐3‐silacyclopent‐5‐ene – Synthese und Reaktionen

Abstract

Abstract1,2‐Diaza‐3‐silacyclopent‐5‐ene – Synthesis and ReactionsThe dilithium salt of bis(tert‐butyl‐trimethylsilylmethylen)ketazine (1) forms an imine‐enamine salt. 1 reacts with halosilanes in a molar ratio of 1:1 to give 1,2‐diaza‐3‐silacyclopent‐5‐enes. Me3SiCH=CCMe3 [N(SiR,R′)‐N=C‐C]HSiMe3 (2‐7). (2: R,R′ = Cl; 3: R = CH3, R′ = Ph; 4: R = F, R′ = CMe3; 5: R = F, R′ = Ph; 6: R = F, R′ = N(SiMe3)2; 7: R = F, R′ = N(CMe3)SiMe3). In the reaction of 1 with tetrafluorosilane the spirocyclus 8 is isolated. The five‐membered ring compounds 2‐7 and compound 9 substituted on the silicon‐fluoro‐ and (tert‐butyltrimethylsilyl) are acid at the C(4)‐atom and therefore can be lithiated. Experiments to prepare lithium salts of 4 with MeLi, n‐BuLi and PhLi gave LiF and the substitution‐products 10‐12. 9 forms a lithium salt which reacts with ClSiMe3 to give LiCl and the SiMe3 ring system (13) substituted at the C(4)‐atom. The ring compounds 3‐7 and 10‐12 form isomers, the formation is discussed. Results of the crystal structure and analyses of 8, 10, 12, and 13 are presented.

Synthesis, conformational, spectroscopic and chemical reactivity analysis of 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide using experimental and quantum chemical approaches

“…Intra and intermolecular hydrogen bonds are classified in two categories red and blue shifts depending upon the nature of vibrational frequencies shift in groups involved in the hydrogen bridges [15].…”

“…Hydrazides and their derivatives are versatile intermediates for the syntheses of vast number of heterocyclic derivatives [14][15][16]. Hydrazides and their derivatives possess different biological activity.…”

Synthesis and Spectral Characterization of Hydrazone Schiff Bases Derived from 2,4-Dinitrophenylhydrazine. Crystal Structure of Salicylaldehyde-2,4-Dinitrophenylhydrazone

“…Hydrazones, RR C=N-NR R , are used as intermediates in synthesis [1], as functional groups in metal carbonyls [2], in organic compounds [3,4] and in particular in hydrazone Schiff base ligands ( Fig. 1) [5 -8], which are among others employed in dinuclear catalysts [9].…”

From lithium ketazides to isomeric silylketazine-rings – imine-enamine tautomerism

“…Recently represented reactions of lithiated ketazines with haloboranes [5,6], -silanes [7,8], and -phosphanes [6] yielded surprising results, e.g., the backbone of the ketimine structure is maintained in reactions with halotriorganylsilanes [7,8]. On the other hand, half an imine-enamine isomerization occurs in reactions with dihaloboranes, -silanes, and -phosphanes [4,8].…”

“…On the other hand, half an imine-enamine isomerization occurs in reactions with dihaloboranes, -silanes, and -phosphanes [4,8]. Five-membered rings with an endocyclic imine-and exocyclic enamine-bond are obtained.…”