Reactions of polychlorophenyllithium compounds with electrophiles

In situ generation and trapping of aryllithium and arylpotassium species by halogen, sulfur, and carbon electrophiles

A general method has been developed for in situ trapping of arylmetal intermediates by halogen, sulfur, ketone, and aldehyde electrophiles affording the functionalization of the most acidic position in arene. Pentafluorobenzene, benzothiazole, and benzoxazole can be functionalized by using K(3)PO(4) base. For less acidic arenes, tBuOLi base is required. Arenes with DMSO pK(a) values of 35 or less are reactive.

A simple base-mediated halogenation of acidic sp2 C-H bonds under noncryogenic conditions

A new method has been developed for in situ halogenation of acidic sp(2) carbon-hydrogen bonds in heterocycles and electron-deficient arenes. Either selective monohalogenation or one-step exhaustive polyhalogenation is possible for substrates possessing several C-H bonds that are flanked by electron-withdrawing groups. For the most acidic arenes, such as pentafluorobenzene, K(3)PO(4) base can be employed instead of BuLi for metalation/halogenation sequences.