title: Mechanistic Insight into the Dehydro-Diels-Alder Reaction of Styrene-Ynes.
abstract: The Diels-Alder reaction represents one of the most thoroughly studied and well-understood synthetic transformations for the assembly of six-membered rings. Although intramolecular dehydro-Diels-Alder (IMDDA) reactions have previously been employed for the preparation of naphthalene and dihydronaphthalene substrates, low yields and product mixtures have reduced the impact and scope of this reaction. Through the mechanistic studies described within, we have confirmed that the thermal IMDDA reaction of styrene-ynes produces a naphthalene product via loss of hydrogen gas from the initially formed cycloadduct, a tetraenyl intermediate. Alternatively, the dihydronaphthalene product is afforded from the same tetraenyl intermediate via a radical isomerization process. Moreover, we have identified conditions that can be used to achieve efficient, high-yielding, and selective IMDDA reactions of styrene-ynes to form either naphthalene or dihydronaphthalene products. The operational simplicity and retrosynthetic orthogonality of this method for the preparation of naphthalenes and dihydronaphthalenes makes this transformation appealing for the synthesis of medicinal and material targets. The mechanistic studies within may impact the development of other thermal transformations.
authors: Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15206, United States.
authors: Laura S
authors: LS
authors: Kocsis
authors: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors: Husain N
authors: HN
authors: Kagalwala
authors: Department of Chemistry, University of California-Davis , Davis, California 95616, United States.
authors: Sharlene
authors: S
authors: Mutto
authors: Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15206, United States.
authors: Bhaskar
authors: B
authors: Godugu
authors: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors: Stefan
authors: S
authors: Bernhard
authors: Department of Chemistry, University of California-Davis , Davis, California 95616, United States.
authors: Dean J
authors: DJ
authors: Tantillo
authors: Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15206, United States.
authors: Kay M
authors: KM
authors: Brummond
mesh_terms: D061565:Cycloaddition Reaction; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D013237:Stereoisomerism; D020058:Styrene / Q000737:chemistry*; D013696:Temperature
chemical_list: D009281:Naphthalenes; C031721:naphthalene; D020058:Styrene