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.
Allen, J. C., Kociok-Kohn, G., & Frost, C. G. (2012). Rhodium-catalysed enantioselective synthesis of 4-arylchroman-2-ones. Organic and Biomolecular Chemistry, 10(1), 32-35. https://doi.org/10.1039/c1ob06586f