Hetero-Diels-Alder reaction of 3-aryl-2-benzoyl-2-propenenitriles with enol ethers. Synthesis of 2-alkoxy-3,4-dihydro-2H-pyran-5-carbonitriles

摘要

The hetero-Diels-Alder reaction of 3-aryl-2-benzoyl-2-propenenitriles 1a-d with enol ethers 2a-c yields cis/trans diastereoisomers of 2-alkoxy-4,6-diaryl-3,4-dihydro-2H-pyran-5-carbonitriles 3 and 4 in 79-98% yield. The similar reaction of 1a-c with cyclic enol ether 5 affords diastereoisomeric cycloadducts 6 and 7 with cis annulated pyran rings. Reaction of 3 with sulfuric acid leads to 2-hydroxy-3,4-dihydro-2H-pyran-5-carbonitriles 8 and 9.