Cossy synthesis

Total Synthesis of Eight-Membered Lactones 211 5.2.2.9 Cossy Synthesis of the Lactone Moiety (2005)... 

The utility of RCM methodology for the synthesis of open-chain building blocks from a,fi-unsaturated d-lactones is exemplified by the partial syntheses of Cossy aimed for (+)-methynolide (the aglycon of the methymicin family of macrolide antibiotics) [45], and the anticancer agent discodermolide [46], as well as during a recent total synthesis of the highly cytotoxic marine natural depsipeptide apratoxin A by Forsyth and Chen [47]. 

Scheme 60 (E)-Selective CM with electron-deficient alkene in Cossy s total synthesis of strictifolione (308) [139b]...

Scheme 13.49. Prelog-Djerassi Lactone Synthesis J. Cossy, D. Bauer, and V. Bellosta8...

A novel lactone and lactol synthesis was achieved by Cossy and coworkers [268], usinga CM followedby ahydrogenationandaringclosure. Ina typical procedure, aso-lution of acrylic acid or acrolein and an allylic or homoallyhc alcohol is stirred at room temperature under 1 atm of H2 in the presence of the ruthenium catalyst 6/3-16a and Pt02. Under these conditions, the homoallylic alcohols 6/3-101 (n= 1) and acrylic acid 6/3-102 led to the lactones 6/3-103 and the reduced alcohol 6/3-104 with acrolein, the corresponding lactols were obtained, together with 6/3-104 (Scheme 6/3.30). 

Pyrrolizinone 246 is a key intermediate in the synthesis of the ML-3000 drug which was described by Cossy and Belotti <1997JOC7900> this pyrrolizinone intermediate was constructed in one-step (68%), via a thermal acid-promoted intramolecular bicyclization of the iu-acetylenic amino ester 245 by heating at 150 °C in presence of pivaloic acid (1 equiv) (Scheme 66). 

J. Cossy, C. Willis, V. Bellosta, and L. Saint-Jalmes, Synthesis, 2002, 951. 

A photoreductive strategy for a short total synthesis of the sesquiterpene ( )isoafricanol was developed by Cossy et al. Thereby, the hydroazulenol skeleton was generated by photoreductive cyclization of an unsaturated ketone employing triethylamine as the electron donor (Scheme 40) [61],... 

A recent synthesis of zincophorin methyl ester by Cossy and coworkers employs allenylzinc methodology to construct a side chain anti,syn stereotriad (Figure l)26. 

For reviews of various aspects of this subject, see Cossy Carrupt Vogel, in Patai Supplement A The Chemistry of Double-bonded Functional Groups, vol. 2, pt. 2 Wiley New York, 1989, pp. 1369-1565 Kcmernitskii Ignatov Levina Russ. Chem. Rev. 1988, 57, 270 282 Weedon, in Horspool, Ref. 966, pp. 61-143 Lenz Rev. Chem. Intermed. 1981, 4, 369-404 Margaretha Chimin 1975, 29, 203-209 Bauslaugh Synthesis 1970, 287-300 Eaton Acc. Chem. Res. 

BouzBouz, S. Cossy, J. Efficient strategy for the synthesis of stereopentad subunits of scytophydn, rifamycin S, and discodermolide. Org. Lett. 2001, 3, 3995-3998. 

Belotti, D., Cossy, J., Pete, J.P., and Portella, C. (1986) Synthesis of bicyclic cyclopentanols by photoreductive cyclization of 8,e-unsaturated ketones. Journal of Organic Chemistry, 51, 4196-4200. 

Cossy J, Arseniyadis S, Meyer C (eds) (2010) Metathesis in natural product synthesis. Wiley-VCH, Weinheim... 

Cossy and co-workers reported the synthesis of a variety of 3-oxacycloalkenes via RCM <02TL7263> (Scheme 37). Further transformations of these compounds, such as oi-oxyalkylation and cuprate addition to the enone were also reported. 

As (—)-pulegone is not readily available, subsequent work addressed the natural enantiomer by different methods [12], but all completed their synthesis via Snider s enone (17). Asaoka utilised a TMS group as temporary directing volume (Scheme 5) [12a]. Cossy applied a photore-ductive cyclopropane ring opening, which was obtained by a diastereoselective Simmons-Smith reaction [12b]. Schmalz finally used a planar-chiral arene complex to synthesise enone 17 with interesting CrfCO), chemistry [12c]. 

Nelson A (2005) Product class 7 ynones. In Cossy J (ed) Science of synthesis, vol 26. Georg Thieme, Stuttgart, pp 971-988... 

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