A possible solution to the problem is to adapt the profile calculated for three-spin system to a system with more spins by adjusting the parameters . In fact, this is equivalent to approximating a complex system by the three-spin system of two protons and a single C nucleus. Such an approach predicts a reasonable enhancement of the transfer efficiency for systems in which the protons stemming from pH2 have large direct couplings to the target C nucleus. This holds to some extent for ethyl acetate, another candidate for PHIP-SAH method, but for allyl pyruvate this approximation breaks down.