Oxocane synthesis

The excision of the keto bridge present in tricyclo[5.3.1.1 ]dodecan-l 1-one taken from the work of Cha et al. on synthetic studies of taxol deserves special mention. Highly functionalized derivatives of bicyclo]5.3.1]undecane are obtained using the DIB/I2 system (Eq. 11) [38]. The fragmentation of a related derivative of oxabicyclo[3.3.1]nonan-9-one is used by the same authors as a key step in the synthesis of cK-2,8-disubstituted oxocanes (Eq. 12) [39]. 

Smith AB III, Haseltine JN, Visnick M (1989) Tremorgenic indole alkaloid studies. 6. Preparation of an advanced intermediate for the synthesis of penitrem D. Synthesis of an indole-oxocane. Tetrahedron 45 2431-2449... 

Scheme 13 Stereoselective synthesis of the oxocane ring of (+)-laurencin...

An elegant example of BF3 OEt2-promoted epoxide ring opening was reported by Parrain and coworkers (Equation 34) [35]. This method represents the first S-exo selective oxacyclization approach toward the synthesis of bridged bis-oxocane type compounds such as (54). 

Oishi, T., Shoji, M., Maeda, K., Kumahara, N., and Hirama, M. (1996) Extensive ring-expansion strategy for the enantioselective synthesis of the medium ring ethers, oxepene, oxocane, and oxonene, of ciguatoxin. Synlett, 1165-1167. 

Kruger, J. and Hoffmann, R.W. (1997) Substituted oxocanes by intramolecular allylboration reactions. Entry to an efficient synthesis of (-l-)-laurencin.y. Am. Chem. Soc., 119, 7499-7504. 

Carling, R.W. and Holmes, A.B. (1986) A new synthetic method for the preparation of 2,8-disubstituted oxocane derivatives synthesis of lauthisan and laurenan. /. Chem. Soc. Chem. Commun., 565-567. 

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