Ene Reaction of Singlet Oxygen, Triazolinedione, and Nitrosoarene with Chiral Deuterium-Labeled Allylic Alcohols: The Interdependence of Diastereoselectivity and Regioselectivity Discloses Mechanistic

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• 作者：Waldemar Adam ; Nils Bottke ; Oliver Krebs ; Ioannis Lykakis ; Michael Orfanopoulos ; and Manolis Stratakis
• 刊名：Journal of the American Chemical Society
• 出版年：2002
• 出版时间：December 4, 2002
• 年：2002
• 卷：124
• 期：48
• 页码：14403 - 14409
• 全文大小：150K
• 年卷期：v.124,no.48(December 4, 2002)
• ISSN：1520-5126

文摘

The ene reaction of singlet oxygen (¹O₂), triazolinedione (TAD), and nitrosoarene, specifically4-nitronitrosobenzene (ArNO), with the tetrasubstituted 1,3-allylically strained, chiral allylic alcohol 3,4-dimethylpent-3-en-2-ol (2) leads to the threo-configured ene products in high diastereoselectivity, aconsequence of the hydroxy-group directivity. Hydrogen bonding favors formation of the threo-configuredencounter complex threo-EC in the early stage of ene reaction. For the analogous twix deuterium-labeledallylic alcohol Z-2-d₃, a hitherto unrecognized dichotomy between ¹O₂ and the ArNO and TAD enophiles isdisclosed in the regioselectivity of the tetrasubstituted alcohol: Whereas for ArNO and TAD, hydrogenbonding with the allylic hydroxy group dictates the regioselectivity (twix selectivity), for ¹O₂, the cis effectdominates (twin/trix selectivity). From the interdependence between the twix/twin regioselectivity and thethreo/erythro diastereoselectivity, it has been recognized that the enophile also attacks the allylic alcoholfrom the erythro face without assistance by hydrogen bonding with the allylic hydroxy functionality.