ISSN:
0170-2041
Keywords:
Pyridines
;
Alkaloids
;
Theonelladines A-D
;
Niphatesine A
;
4-(3-Pyridyl)-1-butin
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Syntheses of the Theonelladines A, B, C, D and of Niphatesine AThe pyridine alkaloids theonelladine A-D (1-4) and niphatesine (5) of marine origin have been synthesized starting either from 3-(4,4-dibromo-3-butenyl)pyridine (6) or from 3-pyridinecarbaldehyde. Reaction of 6 with two equivalents of BuLi gave the lithiated derivative of the alkyne 7, which could be alkylated with 1-bromo-10-(tetrahydro-2-pyranyloxy)decane (8) to yield the alkynol 9 after methanolysis. Selective hydrogenation of 9 with Lindlar palladium catalyst gave (Z)-14-(3-pyridyl)-11-tetradecan-1-ol (11). - Addition of the Grignard reagent of 12-(benzyloxy)-1-bromododecane (13) to 3-pyridinecarbaldehyde gave 17, which was first oxidized (Swern) to give 18 and then reduced (Wolff-Kishner) to give 14. Hydrogenolysis of the benzyl ether 14 yielded 15. The alcohol group in 9, 11, and 15 was converted into the tosyloxy group by reaction with tosyl chloride/pyridine. Subsequent reactions of the tosylates 10, 12, and 16 either with an excess of methylamine/ethanol or of ammonia/ethanol gave the pyridine alkaloids 1-5 in high yields as p-toluenesulfonates.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199319930129
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