Abstract:
New and robust methodologies have been designed for palladiumcatalyzed
cross-coupling reactions involving a library of novel tertiary phosphine
ligands incorporating a phospha-adamantane framework. The secondary phosphine,
l,3,5,7-tetramethyl-2,4,8-trioxa-6-phospha-adamantane was converted into a small
library of tertiary phosphine derivatives and the ability of these tertiary phosphaadamantanes
to act as effective ligands in the palladium-catalyzed amination
reaction and p-alkyl-Suzuki cross-coupling was examined. l,3,5,7-Tetramethyl-6-
phenyl-2,4,8-trioxa-6-phosphaadamantane (PA-Ph) used in combination with
Pd2(dba)3 CHCI3 facilitated the reaction of an array of aryl iodides, bromides and
chlorides with a variety secondary and primary amines to give tertiary and
secondary amines respectively in good to excellent yields. 8-(2,4-Dimethoxyphenyl)-
l,3,5,7-tetramethyl-2,4,6-trioxa-8-phospha-tricyclo[3.3.1.1*3,7*]decane
used in combination with Pd(0Ac)2 permitted the reaction of an array of alkyl
iodides, and bromides with a variety aryl boronic acids and alkyl 9-BBN
compounds in good to excellent yields. Subsequent to this work, the use of
phosphorous based ionic liquids, specifically tetradecyltrihexylphosphonium
chloride (THPC), in the Heck reaction provided good to excellent yields in the
coupling of aryl iodides and bromides with a variety of olefins.
