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The Type 2 Intramolecular Diels-Alder Reaction

The Type 2 Intramolecular Diels-Alder Reaction. Tether is attached to the 1 position of the diene Leads to fused bicycles. Tether is attached to the 2 position of the diene Leads to bridged bicycles with bridgehead double bonds Tether can control regioselectivity, stereoselectivity, and

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The Type 2 Intramolecular Diels-Alder Reaction

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  1. The Type 2 Intramolecular Diels-Alder Reaction • Tether is attached to the 1 position of the diene • Leads to fused bicycles • Tether is attached to the 2 position of the diene • Leads to bridged bicycles with bridgehead double bonds • Tether can control regioselectivity, stereoselectivity, and • p-facial selectivity

  2. Hetero Type 2 Diels-Alder Reactions • Previous work in the area of hetero type 2 Diels-Alder reactions has shown N-acyl • imines to participate in the Diels-Alder reaction to provide bridgehead amides.1 • Current studies are looking to expand the scope of the type 2 hetero intramolecular • Diels-Alder reactions. • The use of a more reactive hetero dienophile is being investigated.

  3. Type 2 Intramolecular Nitroso Diels-Alder Reactions • The type two intramolecular Diels-Alder cycloaddition of N-acylnitroso dienophiles • is currently being studied for the synthesis of bridged [n,3,1] oxazinolactams. • In situ oxidation of hydroxamic acids provide N-acyl nitroso dienophiles which • undergo cycloaddition to provide 3,6 dihydro-1,2 oxazines. • These cycloadducts can subsequently be transformed into medium ring amides • and amines.

  4. Synthesis of Precursor HydroxamicAcids

  5. Synthesis of Bridged [n,3,1] Oxazinolactams

  6. 9, 10-Dimethylanthracene Adducts

  7. Regiochemistry of T2IMNDA

  8. Measuring Bridgehead Olefin Distortion • Two parameters,  and , are used to quantify the degree of distortion in a strained olefin.2 • , which represents the angle between the p-orbitals of a  bond, is measured by •  = (1 + 2)/2 shown in composite structure V. • , the pyramidalization angle of the constituent atoms of the  system, is defined as the • acute angle formed by the projection of one substituent (Z) across the atom onto the • geminal substituent (Y). For an sp2.00 atom,  = 0.0˚, while for an sp3.00 atom,  =60.0˚.

  9. X-Ray Crystal Structures 4 5 Parameter4 5 tC4-C5 6.83(9)° 3.53(9)° cC5 20.3° 13.5° tN1-C9 3.53(9)° tN1-C10 10.35(8)° cC9 0.4° cC10 1.5° cN1 54.8° 52.6°

  10. Functionalization of Bridged Oxazinolactams

  11. Work in Progress

  12. References and Acknowledgements • 1. “The Type 2 Intramolecular Imino Diels-Alder Reaction. Synthesis and Structural Characterization • Of Bicyclo [n,3,1] Bridgehead Olefin/Bridgehead Lactams. Shea, K.J., Lease, T.G.: J. Am. Chem. • Soc. 1993, 115, 2248 • 2. Winkler, F. K.: Dunitz, J. D. J. Mol. Biol.1971, 59, 169-182. • Financial Support of this work from the Undergraduate Research Opportunities Program is • gratefully acknowledged. • Financial Support of this work from Allergan is gratefully acknowledged. • Travel Funding from the UCI CAMP program is gratefully acknowledged.

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