I. Persistent radicals for dynamic nuclear polarization : II. Synthesis of substituted indoles

Abstract

Part I: An brief introduction to dynamic nuclear polarization (DNP) is provided including a discussion of polarization mechanisms and development of new polarization methods in a historical context. Efficient synthesis of highly water-soluble BDPA derivatives that preserve the desirable DNP properties of BDPA and expand its application to aqueous systems is described. The narrow line radical applications in magnetic resonance spectroscopic imaging (MRSI) are investigated focusing on thermal mixing (TM) DNP of pyruvic acid. Design considerations and efforts toward the synthesis of bi- and multiradicals for Cross Effect (CE) DNP, and experiments performed with mixtures of radicals and covalently bound hetero-biradicals are reported. Part II: Indoles are important heterocycles because of their presence as common structural motifs in natural products and pharmaceutical candidates. Second generation Danheiser benzannulation-tandem cyclization approach was developed and applied toward the synthesis of highly substituted indoles. Substrate synthesis, benzannulation results and product elaboration are described.