Indazole 3-lithio

In different seetions of this ehapter, pyrazoles and indazoles C-linked to a metal or a metalloid have been deseribed or they will be deseribed in the preparative seetions, ineluding lithio derivatives (Seetion 4.04.2.1.7), pyrazolylmagnesium reagents (Seetion 4.04.2.3.7(iii)), ehloromereury derivatives (Seetion 4.04.2.1.4(vii)) and silylpyrazoles (Section 4.04.3.1.2(ii)). All these compounds are useful intermediates and some of their most characteristic reactions will be dijcussed here. 

New zwitterionic heterocycles have been derived from l-chloro(dimethyl)silyl-1-borylalkenes and 2-lithio-l-methylimidazole or 1-lithio-indazole. The zwitterionic products are obtained amongst other minor products. A DFT theoretical study has been made of borepin and its analogues the aminoborepins, methylated borepins, dibenzoborepins and tribenzoborepin. The interest here is to determine which of these compounds are planar and which are non-planar. Some of these compounds are, of course, known and here measured and B NMR chemical shifts agree well with the calculations. The calculations predict that tribenzoborepin and two of the dibenzoborepins are non-planar. 

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