A formyl equivalent was generated in situ from Eschenmoser's salt in aqueous THF and was reacted with an allylindium species. Acylnitroso-derived hetero-Diels Alder adducts and related allyl acetates were shown to be substrates for Pd(0)/InI-mediated allylations of formaldehyde-related species to provide homoallylic alcohols. Hydroxymethyl groups were installed with regio- and diastereocontrol to provide relevant disubstituted carbocyclic scaffolds. Enantiopure anti-disubstituted cyclopentene products were prepared from a chiral allyl acetate.