Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• Diels–Alder reaction, Claisen rearrangement, cross-metathesis, and cross-enyne metathesis are used. The synergistic combination of these powerful reactions is found to be useful for the construction of complex targets and fulfill synthetic brevity. Keywords: Claisen rearrangement; Diels–Alder reaction

• a CM in an efficient manner. Biaryl derivatives In view of the interesting properties of biaryl derivatives, we have identified a three-step sequence, which involve cross-enyne metathesis (CEM), DA reaction followed by SM coupling [46]. To this end, acetylene derivatives 96a,b were subjected to CEM

Tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR). An easy entry to linear bicyclic scaffolds

• Javier Miró,
• María Sánchez-Roselló,
• Álvaro Sanz,
• Fernando Rabasa,
• Carlos del Pozo and
• Santos Fustero

Beilstein J. Org. Chem. 2015, 11, 1486–1493, doi:10.3762/bjoc.11.161

• Abstract A new tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR) has been carried out. It involves conjugated ketones, esters or amides bearing a remote olefin and aromatic alkynes as the starting materials. The overall process enables the preparation of a small family of

• linear bicyclic scaffolds in a very simple manner with moderate to good levels of diastereoselectivity. This methodology constitutes one of the few examples that employ olefins differently than ethylene in tandem CEYM–IMDAR protocols. Keywords: bicyclic frameworks; cross enyne metathesis; Diels–Alder

• cross enyne metathesis (CEYM), lagged behind probably due to difficulties in controlling the stereoselectivity in the newly formed double bond leading to the formation of mixtures of E and Z-isomers. These inherent selectivity problems are absent when the olefin counterpart is the ethylene unit, which

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• [141] reported the synthesis of meta-cyclophane 145 at room temperature by ring-closing alkyne metathesis of 1,3-bis(3-pentynyloxymethyl)benzenes (Figure 9). This strategy has also been extended to ortho and para-derivatives. Cross-enyne metathesis: Recently, Kotha and Waghule [142] have synthesized

• diverse crownophanes by using a cross-enyne metathesis and Diels–Alder (DA) reaction as key steps. Here, the macrocycles 146 and 149 were subjected to a cross-enyne metathesis protocol with ethylene to generate the dienes 147 and 150, respectively. These dienes were subjected to a DA reaction with

One-pot cross-enyne metathesis (CEYM)–Diels–Alder reaction of gem-difluoropropargylic alkynes

• Santos Fustero,
• Paula Bello,
• Javier Miró,
• María Sánchez-Roselló,
• Günter Haufe and
• Carlos del Pozo

Beilstein J. Org. Chem. 2013, 9, 2688–2695, doi:10.3762/bjoc.9.305

• Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, D-48149 Münster, Germany 10.3762/bjoc.9.305 Abstract Propargylic difluorides 1 were used as starting substrates in a combination of cross-enyne metathesis and Diels–Alder reactions. Thus, the reaction of 1 with ethylene in the presence of 2nd

• ]. The intramolecular version of this process, the ring closing enyne metathesis (RCEYM) reaction, has found wide application, and several examples can be found in the literature [12][13]. However, the intermolecular version, i.e. the cross-enyne metathesis (CEYM) reaction, has been much less exploited

• this protocol with the aforementioned one (Scheme 1). Results and Discussion In order to prove the efficiency of ethylene-mediated cross-enyne metathesis on our fluorinated alkynes, substrate 1a was chosen as a model substrate. As expected, when a toluene solution of alkyne 1a and 5 mol % of 2nd