TANDEM REVERSE ELECTRON DEMAND DIELS-ALDER REACTIONS OF 1,4-CYCLOHEXADIENE

Reverse-electron demand Diels-Alder reactions of hexachloro cyclopenta diene and -dimethoxy-1,2,3,4-tetrachlorocyclopenta-2,4-diene with 1,4- cyclohexadiene produce the corresponding Diels-Alder adducts in good y ields. The stereochemistry of the intermediates and products was deter mined by NMR techniques and confirmed by X-ray crystal structure deter mination. The following crystal data were found: 2: P2(1), a: 7.8487(4 )Angstrom, b: 14.0176(6)Angstrom, c: 12.1316(7)Angstrom; beta: 707.480 (5)degrees; 3: Pbca, a: 11.8940(5)Angstrom, b: 15.611(1)Angstrom, c: 1 4.7832(5)Angstrom; 5: P2(1)/c, a: 12.3562(7)Angstrom, b: 13.4777(8)Ang strom, c: 15.4430(11)Angstrom, beta: 173.073(5)degrees.