Diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate and its Diels-Alder adduct with cyclopentadiene.
The thermal Diels-Alder cycloadditon reaction of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate, C(16)H(17)NO(5)S, with cyclopentadiene gave the pure racemates of two of the four possible diastereomers, with a complete pi-facial selectivity and a high (80:20) endo/exo-sulfinyl selectivity. X-ray diffraction studies of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate and the major isomer of the cycloaddition product, namely diethyl 3-cyano-3-(toluene-4-sulfinyl)bicyclo[2.2.1]hepta-5-ene-2,2-dicarboxylate, C(21)H(23)NO(5)S, reveal that the conformation of the substituents on the acrylonitrile moiety produces both steric and electronic effects, which affect the stereoselectivity of the reaction.
Toscano
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Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-213, México DF 04510, Mexico. toscano@servidor.unam.mx
Hernández-Ortega
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Ortiz
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Sánchez-Obregón
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Walls
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Yuste
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