ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Methods for a stereoselective preparation of compounds of type 2b, a key intermediate of a previous synthesis of the tetracyclic diterpene stemarin (la), have been tested on model compounds 5a, 5c, and 8a. Thus, (±)-(1RS,6SR,8SR,11SR)-hydroxytricyclo[6.2.2.0l,6]dodecan-9-one (5a) was transformed by the Mitsunobu reaction into (±)-(1RS,6SR,8SR,11RS)-11-(benzoyloxy)tricyclot[6.2.2.01,6]dodecan-9-one (6b; Scheme 2). The latter was also obtained from (±)-(1RS,6SR,8SR,11RS)-11-[(4)-toluenesulfonyloxy]tricyclo[6.2.2.01,6]dodecan-9-one (5c) by the action of Et4N (PhCOO) in acetone. Compound 6b was then converted into (±)-(1RS,6RS,8RS,9RS)-tricyclo[6.2.2.01,6]dodecan-9-ol (8b), a model for 2b. Compound 8b was also prepared from its epimer 8a by the Mitsunobu reaction via ester 7b. The inversion of configuration of bicyclo[2.2.2]octan-2-ols or derivates was not previously described. The model studies paved the way to the diastereoselective synthesis of (+)-18-deoxystemarin (1b) via 12β-hydroxy-13-methyl-9β,13β-ethano-9β-podocarpan-15-one (10a) and 13-methyl-9β,13β-ethano-9β-podpcarpan-12α-ol (11b).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19910740807
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