排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
Prof. Dr. Stephan Schulz Sarah Schmidt Dieter Bläser Christoph Wölper 《无机化学与普通化学杂志》2012,638(11):1705-1710
Zincocene Cp*2Zn reacts with carbodiimides C(NR)2 with insertion into the Zn–Cp* bond and formation of [(Cp*C(NR)2]2Zn [R = Et ( 1 ), iPr ( 2 ), Cy ( 3 )]. In addition, the reaction of Cp*2Zn with CS2 under dry conditions gives (Cp*CS2)2Zn ( 4 ), whereas in the presence of a small amount of water [Zn4(μ4‐O)(S2CCp*)6] ( 5 ) is obtained. Compounds 1 – 4 were characterized by NMR (1H, 13C) and IR spectroscopy as well as elemental analysis and single‐crystal X‐ray diffraction ( 2 – 4 , 5 of poor quality). The solid‐state structure of 5 is comparable to the carboxylate complex previously obtained from the reaction of Cp*2Zn with CO2. 相似文献
2.
3.
4.
5.
A simple one-pot and efficient method is described for the synthesis of pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidinone derivatives 6 via a tandem aza-Wittig/heterocumulene-mediated annulation process. The iminophosphorane 3 reacted with aryl isocyanates, followed by heterocyclization on addition of secondary amines to give the corresponding guanidine intermediates 5, which were cyclized in the presence of a catalytic amount of potassium carbonate to tricyclic compounds 6. Similarly, iminophosphorane 3 reacts with phenols, thiophenol, or ROH to give 2-aryl(alkyl)oxy(thio)pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidinone derivatives 7 in good yields. The corresponding carbodiimide 4c and guanidine-type intermediate compounds 5 could be isolated and characterized, thus confirming the suggested reaction pathway. However, two isomeric pyrazinothienopyrimidinones 8 and 9 may be produced in the reaction of iminophosphorane 3 with aromatic isocyanates and subsequent reaction with primary amines in the presence of a catalytic amount of potassium carbonate. The effects of the nucleophiles and isocyanates on the regioselectivity of the cyclization have been investigated. 相似文献
6.
Yuanyuan Qin Bo Lu Guntram Rauhut Manfred Hagedorn Klaus Banert Chao Song Xianxu Chu Lina Wang Xiaoqing Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17437-17441
Alkynyl isocyanates have been postulated as highly reactive intermediates in synthetic chemistry. Herein, the parent molecule HC≡CNCO is isolated for the first time. In sharp contrast to the previously reported short lifetime (ca. 15 s) at room temperature, we found that HC≡CNCO has a lifetime of 55 h in the gas phase (2 mbar, 300 K) with a melting point of ?79.5 °C and vaporization enthalpy (ΔHvap) of 23.1(1) kJ mol?1. Apart from the IR (gas, solid, and matrix), 1H and 13C NMR, and UV/Vis spectroscopic characterization, its photoisomerization with a acylnitrene HC≡CC(O)N and cyanoketene NCC(H)CO has been observed. 相似文献
7.
8.
Aza-Wittig mediated annulation provides a highly facile and straightforward one-pot strategy for the synthesis of bis(pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidin-4-yl)benzenes 5 and 7. A tandem aza-Wittig reaction of iminophosphorane 2 with 1,4- or 1,3-phenylene diisocyanate, followed by intramolecular heteroconjugate addition annulation after addition of a nucleophilic reagent (amine, phenol, thiophenol or ROH), in presence of catalytic K2CO3 or NaOR, gives selectively the functionalized bis(pyrazinothienopyrimidinones) 5 and 7. 相似文献
9.
10.
An efficient rt synthesis of carbodiimides or ureas from the combination of a titanium imido complex 2 and a range of 12 aryl and aliphatic isocyanates is described. Control experiments suggest that carbodimide formation is via heterocumulene metathesis through a transient intermediate η2-ureato-N,O metallacycle 8. 相似文献