Polar Organometallic Reagents: an Evergreen Tool for Tuning the Reactivity of Unsaturated Systems

The advice of professor Dieter Seebach “Thinking of polar organometallics compounds as carbanions is an impoverishment rather that a simplification” (ISCC, Durham 1984), perfectly fits the statement of professor Manfred Schlosser, who coined the term polar organometallic”, according which no difference in reactivity patterns of organometallic reagents can be rationalized without taking into account the metal counterion and its specific interactions with the accompanying carbon backbone. Both statements stress the need of considering the metal as a key component of these reagents, that can initiate and govern the subsequent reactions. The class of the socalled polar organometallics comprises the reagents of the most common alkali and alkaline earth metals and extend into the area of organozinc derivatives. All these reagents are characterized by a polar carbon-metal bond and the pattern of polarity vary significantly with the metal.