Synthesis of fused tricyclic amines unsubstituted at the ring-junction positions by a cascade condensation, cyclization, cycloaddition then decarbonylation strategy

• Iain Coldham,
• Adam J. M. Burrell,
• Hélène D. S. Guerrand,
• Luke Watson,
• Nathaniel G. Martin and
• Niall Oram

Beilstein J. Org. Chem. 2012, 8, 107–111, doi:10.3762/bjoc.8.11

• positions (such as compound 2, R = H, or other ring sizes) [22]. This paper outlines an approach to such targets using a substituent (to block side reactions) which can then be removed by decarbonylation [23]. Results and Discussion Preparation of the aldehyde substrates We decided to incorporate a one

• protons, was a decarbonylation and this type of reaction is known using Wilkinson’s catalyst [25]. We were disappointed to find that attempts to conduct this decarbonylation using aldehyde 16 and [Rh(PPh3)3Cl] resulted only in decomposition. As an aside, we were interested in using the products of this

• to the core of the alkaloids meloscine and scandine, which contains the same fused tricyclic ring system. The use of glycine to form a ‘non-stabilized’ ylide had led to the desired cycloadduct 14, although subsequent decarbonylation had not been successful using aldehyde 16 (Scheme 5). Despite this

One-pot four-component synthesis of pyrimidyl and pyrazolyl substituted azulenes by glyoxylation–decarbonylative alkynylation–cyclocondensation sequences

• Charlotte F. Gers,
• Julia Rosellen,
• Eugen Merkul and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1173–1181, doi:10.3762/bjoc.7.136

• - and pyrazolylazulenes through the use of glyoxylation–decarbonylative alkynylation–cyclocondensation sequences starting from azulene or guaiazulene as substrates, gives rise to the formation of the target compounds in moderate to good yields. Keywords: azulenes; catalysis; decarbonylation

• proceed in 3-position with both reagents, yet with lower reactivity, and its conversion was found to be incomplete even after 2 h. In addition, the formation of side products [51] and decarbonylation [52] was observed, presumably caused by the steric hindrance of the methyl group in 4-position. Encouraged

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• results in their decarbonylation (or desulfonation in the case of CF3SO2SR) with the production of CF3• radicals, which then react with diaryl- or dialkyl disulfides (Scheme 58). The formation of aryl trifluoromethyl sulfides from thioesters of trifluoroacetic acid occurs in rather better yields (30–40

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• synthesis. Results and Discussion Type of MnO2 used for alkyne deprotection The original paper on the oxidation-decarbonylation of HOM-protected alkynes [60][61] through treatment with MnO2 and powdered KOH does not contain any details about the type of MnO2. We applied this method to the synthesis of

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• and C3 oxidation. In an attempt to conclude the synthesis of FR-900482, substrate 93a was subjected to decarbonylation conditions, using 2.2 equivalents of Wilkinson’s catalyst, (PPh3)3RhCl, to give the corresponding decarbonylated product 93b with retention of configuration of the C10 side chain