The peaks give a similar kinetic trace when normalized, and the decreasing and increasing peaks are mirrored through a horizontal mirror plane, with one exception. For the glycosylations with 1-β the peak at 1590 -1 shows a different behavior as it initially increases and afterward decreases until it reaches a plateau. Upon closer inspection of the peaks as a function of time (Figure B) it is evident that this difference is a consequence of an additional overlapping peak, which is not observed for the glycosylations with 1-α (right plot Figure ). It is seen that for the glycosylations with 1-β (left plot Figure ) the peak has a shoulder to the left, which initially increases and reaches a maximum after 2 hours (purple line), and after that starts decreasing to disappear after 6 hours (black line). This indicates that an intermediate is formed and builds up during the glycosylation with the β-TCA.