New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

• Etienne Borré,
• Frederic Caijo,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2010, 6, 1159–1166, doi:10.3762/bjoc.6.132

• catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions. Keywords: cross-metathesis; kinetic studies; olefin metathesis; RCM; ruthenium

• weak influence on the behaviour of the catalysts in these cases. Finally, the reactivity profiles of 4a and 4g were compared in various metathesis reactions in order to evaluate the influence of the NHC ligand. The last point of our study was the comparison between catalysts in RCM of dienes or enynes

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• diverse suite of δ-lactams because enynes are suitable partners in ring-closing metathesis reactions or cycloisomerizations. An additional benefit of using enynes in metathesis reactions is that the resulting diene product could be further elaborated using a Diels–Alder reaction to construct bi- or

• to other fluorinated 1,7-enynes we isolated the desired lactams (entries 1–3, Table 2). Higher temperatures were required with internal alkynes (entries 2–5, Table 2), where isomerization occurs and the enyne ester 1d did not yield satisfactory results. Interestingly, although enyne ketone 1e gave a

• reaction of fluorinated 1,7-enynes does not permit substitution at the 6-position of the resultant gem-difluoroisoquinolinone (eq 1, Scheme 2), we examined a potential cross metathesis–enyne metathesis tandem-type reaction (CM–EYM reaction). In theory, if the terminal vinyl group of diene 2 can be modified

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• . Saigo reported that the attempted P-K cyclisation of a variety of 3-sila-1,7-enynes underwent cycloisomerisation instead of the cycloaddition (Scheme 1).[7] Saigo's work showed that this cycloisomersiation was only applicable to 3-sila-1,7-enynes and any other chain length would undergo decomposition