1- PrMgCl.LiCl

The reaction of iodo-substituted aryltriazenes 594 with /-PrMgCl LiCl afforded functionalized carbazoles 596. In this reaction, evaporation of i-Prl resulting from the 1/Mg-exchange is important before heating otherwise, unwanted cross-coupling products with i-Prl are observed. Mechanistically, this reaction could proceed with the formation of an arylmagnesium derivative 595 followed by intramolecular addition of the triazene onto nitrogen with the elimination of hydroxylamine (569) (Scheme 5.31). 

Method A /-PrMgCl-LiCl Methods 2 BuLi+n-BuMgCl... 

Formation by acid/base approach. LiCl-activated Grignard reagents such as /-PrMgCl-LiCl are basic enough to deprotonate hindered amines such as HTMP, and TMPMgCl LiCl can be prepared by this way [16]. Note that it is also possible to prepare TMPZnCl LiCl by zinc insertion into TMPCl [17]. 

Selective borylation of aryl versus vinyl iodides has been accomplished by metalation of o-iodo-2-(2-iodovinyl)benzene with PrMgCl LiCl followed by the addition of PrOB-Pin (Scheme 6.21) [45]. This chemistry was valuable since the borylation of the aryl iodides with retention of the vinyl iodide leaves the latter for further functionalization. While only a few substrates were screened in this study, it provided the proof of concept for this line of research. 

A dry and argon-flushed, 10-mL flask with a septum cap is charged with /-PrMgCl LiCl (1 mL, 1.05 m in THF, 1.05 mmol) and cooled to -15 °C. 3,5-Dibromopyridine (37) is added in one portion and the reaction temperature is increased to -10 °C. After the Br/Mg exchange reaction is complete (as indicated by GC analysis of reaction aliquots), allyl bromide (133 mg, 1.1 mmol), and CuCN-2LiCl (one drop, 1.0-M... 

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