ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The ionic reaction of (±)-nerolidol (cis/trans mixture) with N-bromosuccinimide in CCI4 at room temperature afforded 2-methyl-2-vinyl-5-(2-bromo-6-methyl-hept-5-en-2-yl)-tetrahydrofuran (4) in high yield. This compound was readily dehydrobrominated by refluxing collidine to the intermediate allyl vinyl ether 8, which immediately undergoes [3,3]-sigmatropic rearrangement to 2, 5-dimethyl-2-(4-methylpent-3-enyl)-cyclohept-4-enone (11). By treatment with SnCI4 in nitromethane at room temperature 11 was in turn cyclised to cis-3, 3, 7, 10-tetramethyl-2-oxa-tricyclo[5.5.0.01,4]dodec-9-ene (12), an oxetane closely related to the sesquiterpene carotol. This oxetane (12) underwent a stereospecific ring contraction when treated by Lewis acids such as H2AICI or HAlCI2, to form the β-acoratriene (13).Finally, the BF3-catalysed cycli- sation of the latter afforded 2,8-cedradiene (19) from which 2-epi-α-cedrene (20) was easily obtained by partial, regio-selective hydrogenation. α-Cedrene (22) itself, together with its epimer 20, resulted from the Wolff-Kishner reduction of the 2-epi-α-cedren-3-one (21), prepared by selective hydroboration/oxidation of 19.A transformation of nerolidol to α-cedrene was thus achieved by a unique stepwise cyclisation process.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19710540712
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