Ferrocenium Boronic Acid Catalyzed Deoxygenative Coupling of Alcohols with Carbon- and Nitrogen-Based Borate and Silane Nucleophiles

A boronic acid catalyzedcarbon-carbon and carbon-nitrogenbond-forming reaction for the functionalization of various pi-activatedalcohols has been developed. Ferrocenium boronic acid hexafluoroantimonatesalt was identified as an effective catalyst in the direct deoxygenativecoupling of alcohols with a variety of potassium trifluoroborate andorganosilane nucleophiles. In a comparison between these two classesof nucleophiles, the use of organosilanes leads to higher reactionyields, increased diversity of the alcohol substrate scope, and high E/Z selectivity. Furthermore, the reactionproceeds under mild conditions and yields up to 98%. Computationalstudies provide a rationalization for a mechanistic pathway for theretention of E/Z stereochemistrywhen E or Z alkenyl silanes areused as nucleophiles. This methodology is complementary to existingmethodologies for deoxygenative coupling reactions involving organosilanes,and it is effective with a variety of organosilane nucleophile sub-types,including allylic, vinylic, and propargylic trimethylsilanes.

Automated summary

A boronic acid catalyzed carbon-carbon and carbon-nitrogen bond-forming reaction using ferrocenium boronic acid hexafluoroantimonate salt as catalyst has been developed for the functionalization of various pi-activated alcohols. The reaction proceeds under mild conditions and yields up to 98%, with higher yields and selectivity observed when using organosilane nucleophiles. Computational studies provide a mechanistic pathway for the retention of E/Z stereochemistry when using alkenyl silanes as nucleophiles. This methodology is effective with a variety of organosilane nucleophile sub-types, including allylic, vinylic, and propargylic trimethylsilanes.