Bicyclo undecanes synthesis

Previous work by Holton [15] on the synthesis of taxane ring systems, indicated that the preparation of the bicyclo[5.3.1]undecane skeleton lies basically on the work of Biichi on patchouli alcohol [16], which led him to the development of the so-called "epoxy alcohol fragmentation" [15a]. 

An ingenious synthesis of the functionalized bicyclo[6.2.1]undecane ring 423 system was recently devised (equation 176). After rearrangement of 421, an eight-ring lactam 422 was formed. Cleavage of the amide provided the basic ring framework of the bicyclic compound 423. 

The photoisomerization of 2-(pent-4-enyl)-3-oxycyclohex-2-enones 5 to 6-oxytricyclo[6.3.0.01,6]-undecan-2-ones 6 has been used as a key step for the synthesis of sesquiterpenes containing the bicyclo[6.3.0]undecane carbon skeleton.15 16... 

The sesquiterpene (+)-asteriscanolide 1 was first isolated from Asteriscus aquaticus L and characterized by San Feliciano in 1985.1 It has captured the attention of organic chemists mainly because of its uncommon bicyclo[6.3.0]undecane ring system bridged by a butyrolactone fragment. The only prior enantioselective synthesis of 1 has been described by Wender in 1988 featuring an Ni(0)-promoted [4 + 4]-cycloaddition.2 Booker-Milburn and co-workers described the sequential application of intramolecular [2 + 2]-photocycloaddition, Curtius rearrangement, and oxidative fragmentation to produce the 7-desmethyl derivative in 1997.3... 

In the total synthesis of (—)-salsolene oxide (17), an architecturally unusual sesquiterpene with an unsaturated bicyclo[5.3.1]undecane core and trisubstituted... 

Naturally occurring compounds that possess as part of their structures bicyclo[5.3.0]decane and bicy-clo[5.4.0]undecane skeletons are very common in the terpenoid family of natural products. Since both of these carbon frameworks are readily prepared by sigmatropic rearrangement of 3-(2-vinylcyclopropyl) enones, it is not surprising that this method has been applied to the total synthesis of terpenoids. 

MacDougall, J. M., Santora, V. J., Verma, S. K., Turnbull, P., Hernandez, C. R., Moore, H. W. Cyclobutenone-Based Syntheses of Polyquinanes and Bicyclo[6.3.0]undecanes by Tandem Anionic Oxy-Cope Reactions. Total Synthesis of ( )-Precapnelladiene. J. Org. Chem. 1998, 63, 6905-6913. 

The method of Huckin and Weiler has enjoyed widespread use in synthesis. For example, recently reported syntheses of rrans-bicyclo[4.3.1]decan-10-one and a bicyclo[4.4.1]undecan-7-one derivative have employed y-alkylations of 3-keto ester dianions as key steps. This methodology has also been extended to the formation and y-alkylation of dianions of y,8-unsaturated P-keto esters. ... 

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]. 

Suginome, H., Nakayama, Y., Harada, H Hachiro, H., and Orito, K., A new synthesis of a functionalized bicyclo[5.4.0] undecane skeleton based on a sequence involving [2-i-2] photoaddition and regioselective P-scission of alkoxyl radicals from the resulting cyclobutanols, /. Chem. Soc., Chem. Commun., 451,1994 ... 

Mataka s synthetic approach to stacked arene-fused bicyclo[4.4.1]undecanes is illustrated for the benzo-fused compound in Fig. 34a [148]. Briefly, dimethyl 1,3-acetonedicarboxylate is alkylated with two equivalents of a 1,2-bis(bromomethyl) arene (l,2-bis(bromomethyl)benzene in this case) to form the bicycloundecane core. Saponification followed by thermal decarboxylation removes the ester groups. Finally, ketalization affords the stacked compound. Variation of thebis(bromomethyl) arene, and stepwise alkylation with two different bis(bromomethyl)arenes, as shown in Fig. 34b, allows for the synthesis of a series of symmetric and unsymmetric compounds, as illustrated by the examples shown in Fig. 34c. 

Fig. 38 Synthesis of bicyclo[4.4.1]undecane-scaffolded oligo(phenylene vinylene)s si-BU[PE ]2, n = l,3,5 [150]...

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