Download The Chemistry of Zirconacycles and 2,6-Diazasemibullvalenes: by Shaoguang Zhang PDF

By Shaoguang Zhang

In this thesis, the writer introduces recommendations used to build a variety of varieties of N-heterocycles, in accordance with the chemistry of zirconacycles and 2,6-diazasemibullvalenes. within the first half, the writer offers the advance of multi-component cyclization of a zirconacyclobutene-silacyclobutene fused compound, nitriles and unsaturated compounds. those reactions supply synthetically valuable method for numerous N-heterocycles similar to 3-acyl pyrrole, pyrrolo[3,2-d]pyridazine and dihydropyrroloazepine, that are all tough to synthesize by way of different potential. The isolation and characterization of the most important three-fused-ring Zr/Si-containing intermediates also are defined intimately. those effects express that the zirconacyclobutene-silacyclobutene fused compound behaves as a “chemical transformer” upon therapy with numerous substrates through the “coordination-induced skeleton rearrangement” mechanism. within the moment half, the writer demonstrates the synthesis and isolation of a sequence of 2,6-diazasemibullvalenes (NSBVs) from the response of 1,4-dilithio-1,3-dienes and nitriles, highlighting the numerous development made for the 1st time during this paintings: (1) decision of X-ray crystal constitution of a substituted 2,6-diazasemibullvalene; (2) size of the activation barrier of its speedy intramolecular aza-Cope rearrangement in answer; (3) exploration of numerous response kinds of NSBV with different ring-expansion items and “bowl-shape” or “cage-shape” N-containing polycyclic skeletons; (4) demonstration of the localized constitution because the principal shape and the homoaromatic delocalized constitution as a minor part within the equilibrium utilizing theoretical research. in keeping with well-founded effects, this paintings sheds new mild in this debatable topic.

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Extra info for The Chemistry of Zirconacycles and 2,6-Diazasemibullvalenes: Synthesis, Structures, Reactions, and Applications in the Synthesis of Novel N-Heterocycles

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J Am Chem Soc 124:1144–1145 28. Takahashi T, Xi Z, Yamazaki A et al (1998) Cycloaddition reaction of zirconacyclopentadienes to alkynes: highly selective formation of benzene derivatives from three different alkynes. J Am Chem Soc 120:1672–1680 29. Takahashi T, Tsai FY, Li Y et al (1999) Carbon–Carbon Bond formation reaction of zirconacyclopentadienes with alkynes in the presence of Ni(II)-complexes. J Am Chem Soc 121:11093–11100 30. Takahashi T, Liu Y, Iesato A et al (2005) Formation of linear tetramers of diarylalkynes by the Zr/Cr system.

Reproduced from Ref. 79 ppm. Dihydropyrrolo[3,2-c]azepine derivatives 2-18b and 2-19b could also be obtained. The hydrolysis mechanism from the bis(iminoacyl)–Zr intermediates to dihydropyrrolo[3,2-c]azepine derivatives 2-18 and 2-19 is not clear yet [37–39]. 5 One-Pot Synthesis of Pyrrolo[3,2-d]pyridazines and Pyrrole-2,3-Diones via Zirconocene-Mediated Four-Component Coupling of Bis(alkynyl)silane, Nitriles, and Azide Pyrrolo[3,2-d]pyridazines are a class of interesting and useful N-heterocycles [40–42].

5) [36]. 481(3) Å. 5 eq. 4 eq. 12 Intramolecular cyclization of bis(iminoacyl)–Zr complexes to form dihydropyrrolo [3,2-c]azepines Fig. 5 ORTEP drawing of 2-18a and 2-19a with 30 % thermal ellipsoids. Hydrogen atoms are omitted for clarity except polar N–H bonds. Reproduced from Ref. 79 ppm. Dihydropyrrolo[3,2-c]azepine derivatives 2-18b and 2-19b could also be obtained. The hydrolysis mechanism from the bis(iminoacyl)–Zr intermediates to dihydropyrrolo[3,2-c]azepine derivatives 2-18 and 2-19 is not clear yet [37–39].

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