Regioselective Reductive Cross-Coupling Reactions of Unsymmetrical Alkynes

Holly A. Reichard, Martin McLaughlin, Ming Z. Chen, Glenn C. Micalizio
2010 European Journal of Organic Chemistry  
The present microreview summarizes our progress over the last few years in defining regioselective reductive cross-coupling reactions of unsymmetrical alkynes with terminal-and internal alkynes, aldehydes, and imines. We begin with a brief historical perspective of metalmediated reductive dimerization reactions of aromatic alkynes and discuss the challenges associated with "crossed" versions of this mode of reactivity. Next, a collection of available methods that allow for regioselective
more » ... ve cross-coupling of internal alkynes with terminal and internal alkynes, aldehydes, and imines is summarized. After an examination of the requirements for regioselectivity in these cases, the logic behind our design of alkoxide-directed titanium-mediated reductive cross-coupling reactions is presented. A nomenclature is introduced to delineate the presumed mechanistic origin of regioselection associated with each reaction design, and a presentation of alkoxide-directed regioselective reductive cross-coupling reactions of alkynes follows. Throughout, principal issues related to reactivity and selectivity are discussed to assess scope and limitations of available methods and to describe the broad challenges that exist for defining complex fragment union reactions based on reductive cross-coupling chemistry.
doi:10.1002/ejoc.200901094 pmid:24634606 pmcid:PMC3951371 fatcat:k2cvgmtbobd7xavodum7sl6vvm