Palladium-catalyzed gamma-selective and stereospecific allyl-aryl coupling between acyclic allylic esters and arylboronic acids.
Reactions between acyclic (E)-allylic acetates and arylboronic acids in the presence of a palladium catalyst prepared from Pd(OAc)(2), phenanthroline (or bipyridine), and AgSbF(6) (1:1.2:1) proceeded with excellent gamma-selectivity to afford allyl-aryl coupling products with E-configuration. The reactions of alpha-chiral allylic acetates took place with excellent alpha-to-gamma chirality transfer with syn stereochemistry to give allylated arenes with a stereogenic center at the benzylic position. The reaction tolerated a broad range of functional groups in both the allylic acetates and the arylboronic acids. Furthermore, gamma-arylation of cinnamyl alcohol derivatives afforded gem-diarylalkane derivatives containing an unconjugated alkenic substituent. The synthetic utility of this method was demonstrated by its utilization in an efficient synthesis of (+)-sertraline, an antidepressant agent. The observed gamma-regioselectivity and E-1,3-syn stereochemistry were rationalized based on a Pd(II) mechanism involving transmetalation between a cationic mono(acyloxo)palladium(II) complex and arylboronic acid, and directed carbopalladation followed by syn-beta-acyloxy elimination. The results of stoichiometric reactions of palladium complexes related to possible intermediates were fully consistent with the proposed mechanism.
Ohmiya
Hirohisa
H
Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
Makida
Yusuke
Y
Li
Dong
D
Tanabe
Masahito
M
Sawamura
Masaya
M
D000473:Alkanes / Q000138:chemical synthesis* / Q000737:chemistry; D001897:Boronic Acids / Q000737:chemistry*; D002384:Catalysis; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D020005:Propanols / Q000737:chemistry*; D020280:Sertraline / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D000473:Alkanes; D001897:Boronic Acids; D009942:Organometallic Compounds; D020005:Propanols; C006463:allyl alcohol; D010165:Palladium; D020280:Sertraline