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            In the past year we have made significant progress towards the development of a general strategy for the coupling of organic halides with other carbon electrophiles. Initial successes include a general reductive cross-coupling of alkyl halides with aryl halides that is catalyzed by nickel (Figure 1).

            Notably, the reaction is tolerant of even sensitive functional groups, such as unprotected ketones and hydroxyls. While we do not yet have a complete mechanistic understanding of the origin of the high cross-selectivity observed, we have shown that the reaction likely does not proceed by the in situ formation of organomanganese reagents (Figure 2). In a key experiment, tetrakis(dimethylamino)ethylene, an organic reductant similar in potential to zinc, was shown to produce product in good chemical yield and with similar selectivity to reactions that used metallic reductants (Zn and Mn powder).

            We have also become interested in Csp³-Csp³ bond formation by reductive coupling. As an initial foray into this area, we developed a method for dimerizing alkyl halides, alkyl pseudohalides, and allylic acetates under very mild conditions (Figure 3). Prior to this work, no protocol existed for the dimerization of functionalized alkyl halides less reactive than alkyl iodides. Follow-on studies will seek to expand this work to include the cross-coupling of two alkyl halides.

            Collectively, these preliminary studies have revealed the beginnings of a series of general procedures for coupling organic halides with a variety of carbon electrophiles. Future work will focus on expanding the scope of the electrophiles that can be coupled with organic halides and identifying the origins of the observed selectivity.