Rhodium-catalysed enantioselective synthesis of 4-arylchroman-2-ones

The rhodium-catalysed enantioselective 1,4-addition of organoboron reagents to arylidene Meldrum's acids as acceptors, allows convenient access to 4-arylchroman-2-ones with good to excellent levels of enantioselectivity. The use of silyl-protected dioxaborinanes as donors was found to be advantageous to achieving good yields of product under anhydrous conditions.