As far as I could learn from a lit search there are not protocols for neutralizing allelopathic chemicals secreted by the maple. Persistence in the soil is affected by soil PH, temperature, amount of water, and soil composition. Allelopathic chemicals can last for days to years depending on the source and factors listed above. Hardwood mulches are being studied for their weed suppression characteristics but maple hasn’t been studied. Raised beds with new soil will be ready to plant immediately, top dressing with new soil and compost may be enough to reduce any allelopathy or waiting a season may be enough. Several sources state it’s affect is on germination so transplants will probably grow well.