A-patchoulene

In fact, a "diabolic confabulation" of two rearrangements, one in the course of degradation of patchouli alcohol to a-patchoulene (4-5) and another one in the... 

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). 

Although cedranoid sesquiterpenes have earlier been synthesized, a renewed interest in alternative methods for elaborating these frameworks has arisen. The stereo-specific approach to (x-cedrene and a-patchoulene skeletons designed by Deslong-champs and summarized in Scheme XLIII is a case in point Beginning with the Stork-Clarke intermediate 559, the tetracyclic cyclopropyl diketone 560 was elaborated via a series of standard transformations. Treatment of 560 with three equivalents of sodium methoxide in methanol at room temperature for 20 min... 

Erraan and Stonehave devised a new method for the construction of the tricyclic skeleton associated with such sesquiterpenes as a-patchoulene (438) and cyperene (439). The route they employed was the formation of the acid-ester (440 R = OH) by a Diels-Alder reaction of 3-ethoxycarbonyl-2,4-dimethyl-penta-1,3-diene with acrylic acid. The corresponding diazo-ketone (440 R = CHN2), on treatment with boron trifluoride etherate, gave the keto-esters (441) and (442) directly. This direct acid-catalysed cyclization proved to be more efficient than the conventional copper-catalysed thermal decomposition of (440 ... 

Patchouli acetate (431) was also treated in the same medium to give 426 and 429 (Matsui and Miyazawa, 2000). 5-Hydroxy a patchoulene (432) was incubated with G. cingulata to afford la-hydroxy derivative (426) (Miyazawa et al., 1998b). 

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