Background hydrolysis is therefore too fast in the case of acetyl chloride, even if pyridine was added in an attempt to favor the acylation reaction over hydrolysis via nucleophilic catalysis (entry 2). By contrast, less reactive acetic anhydride gave rise to 38% NaphAcPO4 (entry 3) and to nearly quantitative conversion in the presence of pyridine (entry 4). We determined that around 66% of the anhydride is converted to the respective acylphosphate, indicating a surprisingly good fuel-to-waste efficiency of the chemical reaction cycle (Table ). NHS-esters (entry 5-6) represent another class of acylation agents that are commonly used in aqueous environments and exhibit a higher tolerance against hydrolysis, when compared to carboxylic anhydrides. Conversion to NaphAcPO4, turned out to be quite low; however, indicating that acetic anhydride resembles a good balance of reactivity and background hydrolysis, at least for the investigated reference system. Two transacetylation experiments were conducted using acetylphosphate (entry 7-8), yet, without noticeable conversion, which is not too surprising, because the hydrolysis half-life of naphtyl-1-acetylphosphate (NaphAcPO4) is lower compared to that of acetylphosphate (Figure and). Remarkably, the introduction of pyridine consistently led to enhanced activation yields, underscoring the importance of organocatalysis. Other pyridine derivatives and various Lewis base catalysts were also explored and investigated within the reaction network. As can be seen in Figure and Table , the majority of catalysts resulted in enhanced activation yields, notably with electron-deficient pyridine derivative as the most efficient ones.