Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• of cyclopentene-1,4-diol that was obtained by the enzymatic desymmetrization of the corresponding diacetate, an enyne metathesis precursor was accessed by a Mitsunobu-type coupling reaction with propargylic amide. The ring-rearrangement metathesis (RRM) of this enyne precursor was carried out using

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• diastereoselective ring-rearrangement metathesis (dRRM) of cyclopentene 131 (Scheme 12). The presence of a nitro group at the ortho or para positions of the benzyl substituent (134 and 135 in Figure 24), reported by Malinowska and co-workers [45], led to higher activities in the RCM of 7 and 9 (Schemes 1 and 2

Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2016, 12, 1877–1883, doi:10.3762/bjoc.12.177

• property is useful to design norbornene-based ionophores [12]. Due to the strained nature of norbornene systems they are useful precursors for ring-rearrangement metathesis (RRM) [13][14][15][16][17][18][19][20][21] to generate intricate polycyclics involving non-traditional retrosynthetic routes. Recently

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• , Science & Commerce, Matunga, Mumbai–400 019, India Department of Applied Chemistry, Defence Institute of Advanced Technology (DU), Girinagar, Pune–411025, Pune, India 10.3762/bjoc.11.199 Abstract Ring-rearrangement metathesis (RRM) involves multiple metathesis processes such as ring-opening metathesis

• have covered literature that appeared during the last seven years (2008–2014). Keywords: Diels–Alder chemistry; green chemistry; natural products; olefin metathesis; polycycles; ring-rearrangement metathesis; Introduction Transition metal–carbene complexes (Figure 1) introduced during the last two

• molecules. Ring-rearrangement metathesis (RRM) involves a tandem process, where the ring-opening metathesis (ROM) and the RCM sequence occur in tandem to generate complex end products (Figure 2). Several demanding structures related to natural products and non-natural products were synthesized by RRM

Design and synthesis of propellane derivatives and oxa-bowls via ring-rearrangement metathesis as a key step

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1727–1731, doi:10.3762/bjoc.11.188

• Sambasivarao Kotha Rama Gunta Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400 076, India 10.3762/bjoc.11.188 Abstract Various intricate propellane derivatives and oxa-bowls have been synthesized via a ring-rearrangement metathesis (RRM) as a key step starting

• from readily accessible starting materials such as p-benzoquinone, 1,4-naphthoquinone and 1,4-anthraquinone. Keywords: allylation; propellane derivatives; quinones; ring-rearrangement metathesis; Introduction The synthesis of complex target structures requires bond-disconnection analysis of the

• , the ring-rearrangement metathesis (RRM) [8][9][10][11][12] is useful and moreover, the stereochemical information can be transferred from the starting material to the final product during the RRM. In continuation of our interest to design novel molecules via metathesis [13][14][15][16][17][18][19][20

Synthesis of a tricyclic lactam via Beckmann rearrangement and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha,
• Ongolu Ravikumar and
• Jadab Majhi

Beilstein J. Org. Chem. 2015, 11, 1503–1508, doi:10.3762/bjoc.11.163

• -rearrangement metathesis as key steps. Here, we used a simple starting material such as dicyclopentadiene. Keywords: allylation; Beckmann rearrangement; lactams; oximes; ring-rearrangement metathesis; Introduction The Beckmann rearrangement (BR), a well-known protocol for the conversion of ketoxime to an

• reaction at the oxime nitrogen is useful [1][2][3][4][5][6]. Here, we plan to use the BR in combination with a ring-rearrangement metathesis (RRM) [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] to generate lactam derivative 1. The RRM protocol involves a tandem process with several

• Sambasivarao Kotha Ongolu Ravikumar Jadab Majhi Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400 076, India, Fax: 022-25767152 10.3762/bjoc.11.163 Abstract A tricyclic lactam is reported in a four step synthesis sequence via Beckmann rearrangement and ring

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• . Interestingly the starting materials used are simple and commercially available. Keywords: alkenylation; Diels–Alder reaction; ring-rearrangement metathesis; sulfones; Introduction Sulfones [1][2][3][4][5][6][7][8] are popular building blocks [9] in organic synthesis. They are also useful substrates for the

• Ramberg–Bäcklund reaction [10] and they can be alkylated via carbanion chemistry. Moreover, they are suitable synthons in Diels–Alder (DA) reactions [11][12][13][14]. In view of various applications of sulfone derivatives, we envisioned a new synthetic strategy based on ring-rearrangement metathesis (RRM

• -rearrangement metathesis (RRM) as the key steps. This approach delivers tri- and tetracyclic sulfones with six (n = 1), seven (n = 2) or eight-membered (n = 3) fused-ring systems containing trans-ring junctions unlike the conventional all cis-ring junctions generally obtained during the RRM sequence

Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Ongolu Ravikumar

Beilstein J. Org. Chem. 2015, 11, 1259–1264, doi:10.3762/bjoc.11.140

• Sambasivarao Kotha Ongolu Ravikumar Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400 076, India, Fax: 022-25767152 10.3762/bjoc.11.140 Abstract Atom efficient processes such as the Diels–Alder reaction (DA) and the ring-rearrangement metathesis (RRM) have been

• : Diels–Alder reaction; Grignard addition; ring-rearrangement metathesis; polycycles; Introduction Design and synthesis of complex polycycles in a minimum number of steps will enhance the overall synthetic economy of the preparation of a target molecule. The ring-rearrangement metathesis (RRM) is a

Design and synthesis of novel bis-annulated caged polycycles via ring-closing metathesis: pushpakenediol

• Sambasivarao Kotha and
• Mirtunjay Kumar Dipak

Beilstein J. Org. Chem. 2014, 10, 2664–2670, doi:10.3762/bjoc.10.280

• carried out by means of Chem Draw 3D and the structure was visualized with the Mercury software (Figure 3). We turned our attention toward the next target, i.e., the symmetrical heptacyclic diol 27, by adopting the ring-rearrangement metathesis (RRM) protocol [42]. To this end, hexacyclic diones 23 [28

• (400 MHz) spectral data and further supported by 13C NMR spectral data. It was anticipated that the two allyl groups and the cyclohexene moiety present in 24 would undergo a ring-rearrangement metathesis (RRM), [42] which involves the ring-opening and ring-closing metathesis sequence (ROM–RCM) in a

• synthesis of heptacyclic diol 22. The synthesis of diallylated hexacyclic diols. The attempted synthesis of heptacyclic diol via ring-rearrangement metathesis. Supporting Information Supporting Information File 428: Copies of 1H, 13C NMR and HRMS spectra for all new compounds. Acknowledgements We would