Non‐metathesis reactions of ruthenium carbene catalysts and their application to the synthesis of nitrogen‐containing heterocycles

Abstract

Non-metathesis reactions of ruthenium carbene catalysts, such as olefin isomerization, hydrogenation, radical reaction, activation of silane, cyclopropanation, epimerization cocyclopropane, [3 + 2] cycloaddition, and cycloisomerization, are summarized. The utility of these reactions was demonstrated by the synthesis of indole using olefin isomerization and subsequent ring-closing metathesis, the synthesis of indoline using cycloisomerization, and the synthesis of the putative structure of fistulosin using cycloisomerization as a key step.

One‐Flask Tethered Ring Closing Metathesis–Electrocyclic Ring Opening for the Highly Stereoselective Synthesis of Conjugated Z/E‐Dienes

“…As outlined in Scheme 5, our synthesis started with a Cucatalyzed epoxide ring-opening reaction of (R)-propylene oxide with vinylmagnesium chloride. [55,56] The resulting homoallylic alcohol (R)-12 was then converted into ester (R)-11 by a sequential catalytic transformation [57][58][59] comprising three Ru-catalyzed steps, but using just one precata-lyst. First, cross metathesis with methyl acrylate was achieved with second generation catalyst B.…”

Synthesis of Heteroaromatic Compounds by Alkene and Enyne Metathesis

“…Nishida and co-workers reported the synthesis of precursors 35 by Ru-H-catalysed isomerisation of the corresponding allylic sulfonamides 34 (Scheme 14a) [53][54][55]. The Ru-hydride catalyst, in this case, was generated through the combination of G2 and vinyloxytrimethylsilane [54].…”

“…A variety of N-protecting groups (e.g. Ts, Cbz) are compatible with the approach [53]. Bennasar and co-workers have developed an approach that enables the direct synthesis of C-2 alkylated indoles (Scheme 14b) [56].…”

Ring‐Closing Metathesis: Novel Routes to Aromatic Heterocycles

“…[51,52] The RCM of enamine 86 provided the corresponding indole 87 in excellent overall yield. In 2006, Bennassar and co-workers also employed a similar strategy to generate indoles.…”