HA using Pd (PPh,), proceeds regioselectively to give 74 (eq 2, path a, 62% yield) as a 9: l ratio of diastereomers. The high field shifts of the Me3Si group in the minor isomer (6-0.31) compared to the major isomer (6+ 0.12) due to shielding by the benzo ring in the minor isomer leads to the stereochemical assignment depicted in 7 for the major product. Remarkably, performing the same reaction with lb leads to none of the silylylated product ...