Media type: E-Article Title: Pyrimidine‐Annulated Pyrrolobenzodiazepines. A New Ring System Related to Aspergillus Alkaloids Contributor: Schmidt, Andreas; Gholipour Shilabin, Abbas; Christoph Namyslo, Jan; Nieger, Martin; Hemmen, Sascha Published: Wiley, 2005 Published in: European Journal of Organic Chemistry, 2005 (2005) 9, Seite 1781-1789 Language: English DOI: 10.1002/ejoc.200400738 ISSN: 1434-193X; 1099-0690 Origination: Footnote: Description: AbstractPyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione was converted into the corresponding C‐11‐monothiolactam and subsequently treated with amines to give cyclic amidines, which racemize due to the formation of tautomers (NMR, X‐ray analysis) under basic conditions. We treated these amidines with bis(trichlorophenyl) malonate esters. Formation of neutral tautomers of the 1,3,8‐triones of the new 4,7a,12b‐triaza‐dibenzo[e,g]azulene ring system gave a twisted molecule with both helical and chiral structure elements (NMR, X‐ray analysis), which caused a splitting of the NMR signals into two sets. Results of two X‐ray single crystal analyses are presented, together with an ab initio calculation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)