Bicyclo undecanes

In contrast to Nicolaou s synthetic plan, the retrosynthetic analysis of Holton s approach preserves the non-synthetically significant B ring and proceeds through disconnection of bonds which are involved in the D and C rings, to arrive finally to the bicyclo[5.3.1]undecane derivative 32, as the starting material. 

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]. 

Scheme 13.6.8 shows how compound 38. which has the basic bicyclo[5.3.1]undecane ring system of taxol, can be prepared by this procedure from a taxusin intermediate readily available from camphor in either enantiomeric form [15b]. Compare the structure of 40 with a-patchoulene 5, in Scheme 1.1 (pag. 10). 

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

An intramolecular variation of the ene/enone photocycloaddition is described by J. D. Winkler. As already described for the intermolecular transformation (see Demuth s enone cycloaddition reaction), a dioxenone is formed via cyclization of a 3-ketoester and subsequently irradiated. Intramolecular cycloaddition then leads to a strained tetracyclic photoproduct which can be ring-opened and decarboxylated to give the trans-fused bicyclo[5.3.1 ]undecan-11 -one. 

This method provides the basis for a general and efficient route to alkyl-substituted and heterofunctionalized bicyclo[6.4.0]dodecanes and to bicyclo[5.3.1]undecanes. In several model studies, the nickel-catalyzed intramolecular [4 + 4] cycloaddition of bis-dienes has been applied to the construction of diterpene systems, such as taxol (7), crispolide, and vulgarolide13 1S. Thus, in the case of taxol. both AB- and BC-ring fusion is achieved with high yield and high diastereoselectivity13. 

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]. 

A soln. of bicyclo[5.3.1]undecane-8a,lla-diol monotosylate in 1,2-dimethoxy-ethane added during 0.5 hr. to a soln. of LiAlH4 in the same solvent, and the... 

Bazzanenol, a New Sesquiterpene Alcohol Having a Skeleton of Bicyclo[5.3.1]undecane System from Hepaticae Bazzania pompeana (Lac.) Mitt. Experientia 26, 347 (1970). 

Species 88-90 are also recognized to be bicyclo[4.4.1]undecane derivatives. 

Experimental Procedure 2.2.9. [4 + 3] Cycloaddition of a Chromium Carbene Complex to a 2-Aminodiene 6-(2-Furyl)bicyclo[5.4.0]undecan-2,4-dione [264]... 

Finally, l-aza-bicyclo[5.4.0]undecanes are reduction products (see Section 4.3) of, for instance, /J,y-unsaturated amines 25 and 95b (see Scheme 24), iminium salt 60 (see Scheme 16), and enamine 107 (see Scheme 27). 

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. 

Adamantanedimethylium dications 236 Bicyclo[3.3.3]undecane-l,5-diyl dication (manxyl dication) 238 A sulfur-stabilized carbodication 238... 

BICYCLO[3.3.3]UNDECANE-l,5-DIYL DICATION (MANXYL DICATION)... 

B and C rings by preparing a bicyclo[5.4.0]undecane (287) amenable to cyclo-propanation followed by ring opening to generate the cyclooctane B ring (Scheme 4.79). 

The Williams approach to bicyclo[5.4.0]undecane containing molecules such as the cyathins, striatins, dolastanes, clavularanes, grayanotoxins, tiglianes, and daphnanes also utilizes an oxidopyrylium cycloaddition to generate the ether constrained bicyclic (Scheme 4.81) (164). The object of the Williams study was to prepare the bicyclo[5.4.0]undecanes and investigate the regio- and stereocon-trolled oxidation of the substrate. 

Problem 9.36 Draw formulas for (o) isopropylcyclopentane, b) c -l,3-dimethylcyclooctane, (c) bicyclo[4.4. l]undecane, (d) rrarw-l-propyl-4-butylcyclohexane. 

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... 

On the other hand, the bicyclo[3.3.3]undecane-l,5-diyl dication 172 (manxyl dication) was observed first by Olah et al.189 (the 13C NMR spectrum is shown in Figure 3.15) [Eq. (3.45)]. Until the generation of the 1,16-dodecahedryl dication... 

Conversion of an Indole-Based BicycIo[5.3.1]undecane into a Bicyclo[5.4.0]undecane... 

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