An acid-catalyzed 1,4-addition isocyanide-based multicomponent reaction in neat water

A green 1,4-addition isocyanide-based three-component reaction was developed to synthesize chromanones via a facile, mild, and efficient one-pot protocol without a metal catalyst. The 1,4-addition of isocyanides occurred at the C-2 position of chromones instead of the Schiff base in neat water. We found that the hydrogen bond can dictate the stereo-outcome of olefins, providing an effective method for the diastereomer-selective synthesis of this type of chromanone. The novel green synthetic protocol allowed the quick synthesis of complex chromanones in an environmentally friendly manner.