Exploration of substrate scope^a.

^aReactions were performed on a 0.3 mmol scale, unless otherwise noted.

^bSome sites in compounds 10hh, 10jj, 10kk, 10ll and 10mm (shown in their structures, with the deuteration percentage in square brackets) are deuterated. Isolated yields are given. See the ESI for experimental details. Deuterium incorporation was determined by integration of the residual formyl proton in the ¹H NMR spectra.