The crude earthworm extract catalysed domino reactions for the synthesis of coumarin derivativesa.

aOptimized reaction conditions: 11 (4.00 mmol), 12 (1.00 mmol), the crude earthworm extract (150 mg), deionized water (0.15 mL) and DMSO (0.85 mL) at 55°C.bYield of the isolated product after silica gel chromatography.cUn-optimized conditions: salicylaldehyde (3.00 mmol), ethyl acetoacetate (1.00 mmol), the crude earthworm extract (100 mg), deionized water (0.10 mL) and DMSO (0.90 mL) at 30°C.dThe reaction was carried out in the absence of the crude earthworm extract, otherwise under the same conditions as entry 8.