Regiospecific functionalization of methyl C-H bonds of alkyl groups in reagents with heteroatom functionality.
We report the regiospecific, rhodium-catalyzed borylation of saturated terminal C-H bonds in molecules with existing functionality. Moderate to good yields were obtained with the organic substrate in excess and as limiting reagent. The borylations of trialkylamines, protected alcohols, protected ketones, and fluoroalkanes occurred regiospecifically at the methyl group that is least sterically hindered. Reactions were also conducted that probed electronic effects on the alkyl borylation. These reactions showed that the borylation occurred preferentially at the methyl group that is most electron-deficient. Methods to conduct tandem borylation of C-H bonds and conversion of the resulting boronate esters to alcohols, alkylarenes, and alkyltrifluoroborates were also developed.
Lawrence
Joshua D
JD
Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA.
Takahashi
Makoto
M
Bae
Chulsung
C
Hartwig
John F
JF
D000473:Alkanes / Q000138:chemical synthesis / Q000737:chemistry*; D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry; D001896:Boron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002074:Butanones / Q000737:chemistry; D004987:Ethers / Q000138:chemical synthesis / Q000737:chemistry
D000473:Alkanes; D000588:Amines; D001896:Boron Compounds; D002074:Butanones; D004987:Ethers; C463639:bis(pinacolato)diboron