Polyquinane

In order to obtain good yields from a Weiss reaction sequence, the H+-concentration has to be adjusted properly in the reaction mixture. The reaction is usually carried out in a buffered, weakly acidic or weakly basic solution. By the Weiss reaction simple starting materials are converted into a complex product of defined stereochemistry. There is no simpler procedure for the synthesis of the l,5-c -disubstituted bicyclo[3.3.0]octane skeleton it has for example found application in the synthesis of polyquinanes. ... 

Participation of aromatic groups in oxy-Cope reaction sequences enables the synthesis of highly substituted polyquinane ring systems (Scheme 10, <96JOC7976>). 

Chanon, M., Barone, R., Baralotto, C., JuHiard, M., Hendrickson, J.B. (1998) Information Theory Description of Synthetic Strategies in the Polyquinane Series. The Holosynthon Concept. 

This approach can also be used for the synthesis of angularly fused polyquinanes 2-898 [457]. 

Eq. 71 becomes an effective cyclopentenone fusion. Such a sequence has proven to be the preferred preparation of polyquinanes exemplified in Eq. 72 52). 

An elegant approach to polyquinanes has recently been described by Paquette et aL1281 By means of an anionic-pericyclic domino reaction four new C-C bonds are formed in one process. First, a two-fold addition of a vinyl lithium reagent, e.g. cyclopentyl lithium to diisopropyl squarate takes... 

In fact, in the last decade, owing to the great number of new natural products which have been isolated bearing cyclopentane rings and the increasing interest in "polyquinanes", very efficient syntheses of five-membered rings have been developed (for reviews of these new methods, see [8] to [11]). 

Some illustrative examples from the field of polyquinanes are the synthesis of some derivatives of bicyclo[3.3.0]octane 6 (Scheme 6.7) [12] [15] -which have been used in the total syntheses of coriolin, hirsutic acid and quadrone- and the synthesis of triquinacene 7 and some of its derivatives. The retrosynthetic analysis of perhydrotriquinacene-l,4,7-trione (7a) is shown in Scheme 6.7bis. In the actual synthesis the hydroxy groups must be protected either as trialkylsilyl ethers or more conveniently as benzyl ethers [16] [17]. 

L.A. Paquette and A.M. Doherty, "Polyquinane Chemistry", Springer-Verlag, Berlin, 1987, pp. 12-14 and references cited therein see also ref. 1, pp. 24-27. 

In fact, the formation of five-membered rings during the radical cyclisation has been used extensively in the past few years for the synthesis of several polyquinanes. 

Khand annulations (extremely efficient in the synthesis of polyquinanes and cyclopentanoid sesquiterpenes -triquinacene, coriolin, etc.-, among many others). 

Paquette, Leo A. Recent synthetic developments in polyquinane chemistry. 

Bohlmann and his coworkers have continued their impressive pace in the isolation of polyquinane-based natural products. These include paidalianchol (517) p-iso-comene (518), silphinene (5/9) 13-acetoxymodhephene (520) 5-oxo-... 

Paquette, L. A. Recent Synthetic Developments in Polyquinane Chemistry. 119, 1-158 (1984). 

For a recent review see Hudlicky T, Kutchan TM, Naqvi SM (1985) Org. Reactions 33 247 cf. Paquette LA, Doherty AM (1987) Polyquinane chemistry, Springer-Verlag, Heidelberg... 

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