Bis-triflate diphosphine complexes of Pt(II) can be used as catalysts for the hetero Diels-Alder reaction (DA) between simple dienes (isoprene, 2,3-dimethylbutadiene) and glyoxylate esters or simple aldehydes (benzaldehyde, terephthalaldehyde) to yield a variety of substituted dihydropyrans under mild conditions. The reactions produces also hetero-ene products, but the selectivity to hetero Diels-Alder is always high (75-100%). Chiral catalysts based on R-binap yield only low e.e.'s. (C) 2003 Elsevier Science B.V All rights reserved.