1. Otto Diels Institute of Organic Chemistry Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Germany
2. Chemistry Department University College London London WC1H 0AJ United Kingdom
3. Università degli Studi di Cagliari Dipartimento di Scienze Chimiche e Geologiche SS 554 Bivio per Sestu 09042 Monserrato (CA) Italy
4. School of Physical Sciences University of Kent Canterbury CT2 7NH United Kingdom