Syntheses and crystal structures of azafulleroid and aziridinofullerene bearing silyl or germyl benzene
摘要:
Addition of silyl and germylmethyl azides (1) to fullerene C-60 at 50 degrees C through [2+3] cycloaddition led to the formation of the triazoline adducts (2). Subsequently, heating 2 at 100 degrees C in the solid state, caused N-2 extrusion producing two different isomers, [5,6]-azafulleroid (3) and [6,6]-aziridinofullerene (4). The C-13 NMR spectrum of 3 had an absence of resonances in the aliphatic region for the fullerene C-60 cage, showing a fulleroid with CS symmetry. In contrast, 4 exhibited one sp(3) resonance in the aliphatic region for the fullerene C-60 cage, indicative of an aziridinofullerene with C-2V symmetry. However, MALDI-TOF mass characterization was hampered because ion peaks corresponding to the bis-adduct are detected in positive ion mode measurements, whereas the ion peaks [M-N-2] for 2a as well as [M] for 3a and 4a are observed in negative ion measurements. In an effort to obtain X-ray data, silyl and germylphenyl groups were introduced to form intermolecular complexes with fullerene C-60. The X-ray structures of 3c and 3d revealed a strong enhancement of homoconjugation in the bridged annulene moiety based on POAV analysis. The X-ray structures of 3c,d and 4c were confirmed with the detection of silyl and germylphenyl-C-60 interactions, similar to dimethoxyphenyl-C-60 interactions. (C) 2008 Elsevier B. V. All rights reserved.
The reaction between chlorosilanes and (chloromethyl)lithium, generated in situ from bromochloromethane and n-butyllithium, was used to synthesize (chloromethyl)silanes. The method is applicable to a wide variety of chlorosilanes and is particularly useful for silanes that contain such reactive bonds as Si-Si, Si-H, Si-vinyl, and Si-allyl. The corresponding (chloromethyl)silanes are generally prepared in high yield. The method may be extended successfully to bromomethylation and iodomethylation of chlorosilanes, and also to the chloromethylation of the other group 14 element (Ge, Sn, and Pb) halides.
Homologation of halostannanes with carbenoids: a convenient and straightforward one-step access to α-functionalized organotin reagents
作者:Saad Touqeer、Laura Castoldi、Thierry Langer、Wolfgang Holzer、Vittorio Pace
DOI:10.1039/c8cc04786c
日期:——
A direct, single synthetic homologative transformation of halostannanes into mono- or di-substituted methyl analogues is documented. Critical for the success of the operation is the excellent nucleophilicity of carbenoid-like methyllithium reagents (LiCHXY, X, Y = halogen, OR, and CN): by simply individuating the reagents’ substitution pattern, the desired functionalized fragment is delivered to the