Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.|Department of Pharmaceutical Chemistry, Eberhard Karls University, Tübingen, Germany.|Department of Pharmaceutical Chemistry, Eberhard Karls University, Tübingen, Germany.|Department of Pharmaceutical Chemistry, Eberhard Karls University, Tübingen, Germany.|Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.|Department of Pharmaceutical Chemistry, Eberhard Karls University, Tübingen, Germany.|Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.